CCNA Exam Questions Explained

EIGRP SIM (New)

2008-10-20T05:05:00.000-07:00

LAB: EIGRP
Question#
After adding RTR_2 router, no routing updates are being exchanged between RTR_1 and the new location. All other inter connectivity and internet access for the existing locations of the
company are working properly.

The task is to identify the fault(s) and correct the router configuration to provide full connectivity between the routers.

Access to the router CLI can be gained by clicking on the appropriate host.

All passwords on all routers are cisco .

IP addresses are listed in the chart below.

RTR_A#show run
!
!
interface FastEthernet0/0
ip address 192.168.60.97 255.255.255.240
!
interface FastEthernet0/1
ip address 192.168.60.113 255.255.255.240
!
interface Serial0/0
ip address 192.168.36.14 255.255.255.252
clockrate 64000
!

router eigrp 212
network 192.168.36.0
network 192.168.60.0
no auto-summary
!

RTR_A#show ip route
192.168.36.0/30 is subnetted, 1 subnets
C 192.168.36.12 is directly connected, Serial 0/0
192.168.60.0/24 is variably subnetted, 5 subnets, 2 masks
C 192.168.60.96/28 is directly connected, FastEthernet0/0
C 192.168.60.112/28 is directly connected, FastEthernet0/1
D 192.168.60.128/28 [ 90/21026560 ] via 192.168.36.13, 00:00:57, Serial 0/0
D 192.168.60.144/28 [ 90/21026560 ] via 192.168.36.13, 00:00:57, Serial 0/0
D 192.168.60.24/30 [ 90/21026560 ] via 192.168.36.13, 00:00:57, Serial 0/0
D* 198.0.18.0 [ 90/21026560 ] via 192.168.36.13, 00:00:57, Serial 0/0

********************************************************************************

RTR_2#show run
!
!
interface FastEthernet0/0
ip address 192.168.77.34 255.255.255.252
!
interface FastEthernet0/1
ip address 192.168.60.65 255.255.255.240
!
interface FastEthernet1/0
ip address 192.168.60.81 255.255.255.240
!
!

router eigrp 22
network 192.168.77.0
network 192.168.60.0
no auto-summary
!

RTR_2#show ip route
192.168.60.0/28 is variably subnetted, 2 subnets
C 192.168.60.80 is directly connected, FastEthernet1/0
C 192.168.60.64 is directly connected, FastEthernet0/1
192.168.77.0/30 is subnetted, 1 subnets
C 192.168.77.32 is directly connected, FastEthernet0/0

**********************************************************

RTR_B#show run
!
interface FastEthernet0/0
ip address 192.168.60.129 255.255.255.240
!
interface FastEthernet0/1
ip address 192.168.60.145 255.255.255.240
!
interface Serial0/1
ip address 192.168.60.26 255.255.255.252

!

router eigrp 212
network 192.168.60.0
!

RTR_B#show ip route
192.168.60.0/24 is variably subnetted, 5 subnets, 2 masks
C 192.168.60.24/30 is directly connected, Serial0/1
C 192.168.60.128/28 is directly connected, FastEthernet0/0
C 192.168.60.144/28 is directly connected, FastEthernet0/1
D 192.168.60.96/28 [ 90/21026560 ] via 192.168.60.25, 00:00:57, Serial 0/1
D 192.168.60.112/28 [ 90/21026560 ] via 192.168.60.25, 00:00:57, Serial 0/1
192.168.36.0/30 is subnetted, 1 subnets
D 192.168.36.12 [ 90/21026560 ] via 192.168.60.25, 00:00:57, Serial 0/1
D* 198.0.18.0 [ 90/21026560 ] via 192.168.60.25, 00:00:57, Serial 0/1

**************************************************************************

RTR_1#show run
!
!
interface FastEthernet0/0
ip address 192.168.77.33 255.255.255.252
!
interface Serial1/0
ip address 198.0.18.6 255.255.255.0
!
!
interface Serial0/0
ip address 192.168.36.13 255.255.255.252
clockrate 64000
!
interface Serial0/1
ip address 192.168.60.25 255.255.255.252
clockrate 64000
!
!

router eigrp 212
network 192.168.36.0
network 192.168.60.0
network 192.168.85.0
network 198.0.18.0
no auto-summary
!
ip classless
ip default-network 198.0.18.0
ip route 0.0.0.0 0.0.0.0 198.0.18.5
ip http server

RTR_1#show ip route
192.168.36.0/30 is subnetted, 1 subnets
C 192.168.36.12 is directly connected, Serial 0/0
192.168.60.0/24 is variably subnetted, 5 subnets, 2 masks
C 192.168.60.24/30 is directly connected, Serial0/1

D 192.168.60.128/28 [ 90/21026560 ] via 192.168.60.26, 00:00:57, Serial 0/1
D 192.168.60.144/28 [ 90/21026560 ] via 192.168.60.26, 00:00:57, Serial 0/1
D 192.168.60.96/28 [ 90/21026560 ] via 192.168.36.14, 00:00:57, Serial 0/0
192.168.77.0/30 is subnetted, 1 subnets
C 192.168.77.32 is directly connected, FastEthernet0/0
C 192.0.18.0/24 is directly connected, Serial 1/0
*S 0.0.0.0 via 198.0.18.5

Explanation:
Step1:
Identify the faults in configuration on RTR_1 and RTR_2. As the SIM specifies all other inter connectivity and internet access for the existing locations of the company are working properly.

Routing Protocols used in the SIM is EIGRP with AS 212 as provided by exhibit.
Faults Identified:

Wrong AS (EIGRP 22) provided at RTR_2 (New router)
RTR_1 does not advertise the new network between RTR_1 and RTR_2 into EIGRP.

We need to correct the above two configuration mistakes to have full connectivity
Step2: Correcting the EIGRP AS to 212
Wrong AS (EIGRP 22) provided at RTR_2 (New router)
All routers that want to exchange routes within EIGRP needs to be in same Autonomous System.

Step 2.1:
First we need to remove the current wrong EIGRP AS 22 from Router RTR_2
Click on Host-F to get CLI of RTR_2

RTR_2>enable
Password : cisco (Provided by SIM Q )
RTR_2#conf t
RTR_2(conf)#
Step 2.2:
Removing the wrong EIGRP routing process with AS 22
RTR_2(conf)#no router eigrp 22
The above statement removes all the EIGRP configuration configured for AS 22 .

Step 2.3:
Adding the correct EIGRP configuration
Start the EIGRP routing process with AS 212
RTR_2(conf)#router eigrp 212
Step 2.4:
Advertise the directly connected networks into EIGRP on RTR_2

Fa 0/0 - 192.168.77.34
Fa 1/0 - 192.168.60.81
Fa 0/1 - 192.168.60.65

RTR_2(config-router)#network 192.168.60.0

RTR_2(config-router)#network 192.168.77.0
RTR_2(config-router)#no auto-summary
RTR_2(config-router)#end

Step 2.5:

Important save the changes made to router RTR_2
RTR_2#copy run start

Step 3:

RTR_1 does not advertise the new network between RTR_1 and RTR_2 into EIGRP.

Click on Host-G to get CLI of RTR_1
The network 192.168.77.0 is used between RTR_1 Fa0/0 - RTR_2 Fa 0/0
This network needs to be advertise into EIGRP routing process at RTR_1
RTR_1>enable
Password : cisco (Provided by SIM Q )
RTR_1#conf t
RTR_1(conf)#
Step 3.1:
Enter EIGRP routing process for AS 212
RTR_1(conf)#router eigrp 212

Step 3.2:
The network 192.168.77.0 is used between RTR_1 Fa0/0 - RTR_2 Fa 0/0 . Advertise this network into EIGRP
RTR_1(config-router)#network 192.168.77.0
RTR_1(config-router)#end

Step 3.3:
Important save the changes made to router RTR_1
RTR_1#copy run start

Verification:

From RTR_2 CLI
ping RTR_1 Serial 1/0 IP address 198.0.18.6
RTR_2#ping 198.0.18.6
!!!!!
A successful ping shows the new RTR_2 will have full connectivity with other routers.

Any Questions are welcomed!!!!!

RIP V2 SIM (New)

2008-08-31T02:50:00.000-07:00

CCNA 640-802 CCNP
LAB: RIP V2
Question#
Central Florida Widgets recently installed a new router in their office (NEW_RTR). Complete the network installation by performing the initial router configurations and configuring RIP V2 routing using the router Command Line Interface (CLI) on the NEW_RTR .

Click on image for larger picture
Configure the router per the following requirements:
1) Name of the router is NEW_RTR
2) Enable-secret password is cisco
3) The password to access user EXEC mode using the console is class
4) The password to allow telnet access to the router is class
5) IPV4 addresses must be configured as follows:
5.1) Ethernet network 209.165.202.128 /27 – Router has the last assignable host
address in subnet.
5.2) Serial Network is 192.0.2.16 /28 - Router has the last assignable host
address in subnet.
6) Interfaces should be enabled.
7) Router protocol is RIPv2

Explanation:
Step1:
Click on the console host, you will get a pop-up screen CLI of Router.
Router>
Configure the new router as per the requirements provided in Lab question
Requirement 1:
Name of the router is NEW_RTR
Step2:
To change the hostname of the router to NEW_RTR follow the below steps
Router>
Router>enable
Router# configure terminal
Router (config)# hostname NEW_RTR
NEW_RTR(config)#

Requirement 2:
Enable-secret password is cisco
Step3:
To set the enable secret password to cisco use the following command
NEW_RTR(config)#enable secret cisco

Requirement 3:
The password to access user EXEC mode using the console is class
Step 4:
We need to configure the line console 0 with the password class
Also remember to type login command after setting up the password on line con 0 which allows router to accept logins via console.
NEW_RTR(config)# line con 0
NEW_RTR(config-line)#password class
NEW_RTR(config-line)#login
NEW_RTR(config-line)# exit
NEW_RTR(config)#

Requirement 4:
The password to allow telnet access to the router is class
Step 5:
To allow telnet access we need to configure the vty lines 0 4 with the password class
Also remember to type login command after setting up the password on line vty 0 4 which allows router to accept logins via telnet.
NEW_RTR(config)# line vty 0 4
NEW_RTR(config-line)#password class
NEW_RTR(config-line)#login
NEW_RTR(config-line)# exit
NEW_RTR(config)#

Requirement 5:
5.1) Ethernet network 209.165.202.128 /27 – Router has the last assignable host
address in subnet.
5.2) Serial Network is 192.0.2.16 /28 - Router has the last assignable host
address in subnet.
Step 6:
Ethernet network 209.165.202.128 /27 – Router has the last assignable host address in subnet.
Ethernet Interface on router NEW_RTR is Fast Ethernet 0/0 as per the exhibit

First we need to identify the subnet mask
Network: 209.165.202.128 /27
Subnet mask: /27: 27 bits = 8 + 8 + 8 + 3
=8(bits).8(bits).8(bits) .11100000 (3bits)
=255.255.255.11100000
=11100000 = 128+64+32+0+0+0+0+0
= 224
Subnet mask: 255.255.255.224
Different subnet networks and there valid first and last assignable host address range for above subnet mask are
Subnet Networks :::::: Valid Host address range :::::: Broadcast address
209.165.202.0 :::::: 209.165.202.1 - 209.165.202.30 ::::: 209.165.202.31
209.165.202.32 :::::: 209.165.202.33 - 209.165.202.62 ::::: 209.165.202.63
209.165.202.64 :::::: 209.165.202.65 - 209.165.202.94 :::::: 209.165.202.95
209.165.202.96 :::::: 209.165.202.97 - 209.165.202.126 :::::: 209.165.202.127
209.165.202.128 :::::: 209.165.202.129 - 209.165.202.158 :::::: 209.165.202.159
209.165.202.160 :::::: 209.165.202.161 - 209.165.202.190 :::::: 209.165.202.191
209.165.202.192 :::::: 209.165.202.193 - 209.165.202.222 :::::: 209.165.202.223
209.165.202.224 :::::: 209.165.202.225 - 209.165.202.254 :::::: 209.165.202.255
Use above table information for network 209.165.202.128 /27 to identify
First assignable host address: 209.165.202.129
Last assignable host address: 209.165.202.158
This IP address (209.165.202.158) which we need to configure on Fast Ethernet 0/0 of the router using the subnet mask 255.255.255.224
NEW_RTR(config)#interface fa 0/0
NEW_RTR(config-if)#ip address 209.165.202.158 255.255.255.224

Requirement 6:
To enable interfaces
Use no shutdown command to enable interfaces
NEW_RTR(config-if)#no shutdown
NEW_RTR(config-if)#exit
Step 7:
Serial Network is 192.0.2.16 /28 - Router has the last assignable host address in subnet.
Serial Interface on NEW_RTR is Serial 0/0/0 as per the exhibit
First we need to identify the subnet mask
Network: 192.0.2.16 /28
Subnet mask: /28: 28bits = 8bits+8bits+8bits+4bits
=8(bits).8(bits).8(bits) .11110000 (4bits)
=255.255.255.11100000
=11100000 = 128+64+32+16+0+0+0+0
= 240
Subnet mask: 255.255.255.240
Different subnet networks and there valid first and last assignable host address range for above subnet mask are
Subnet Networks ::::: Valid Host address ::::::::::: Broadcast address
192.0.2.0 :::::: 192.0.2.1 - 192.0.2.14 ::::::: 192.0.2.15
192.0.2.16 ::::::: 192.0.2.17 - 192.0.2.30 ::::::: 192.0.2.31
192.0.2.32 :::::::: 192.0.2.33 - 192.0.2.46 :::::: 192.0.2.47
and so on ….

Use above table information for network 192.0.2.16 /28 to identify
First assignable host address: 192.0.2.17
Last assignable host address: 192.0.2.30

We need to configure Last assignable host address (192.0.2.30) on serial 0/0/0 using the subnet mask 255.255.255.240

NEW_RTR(config)#interface serial 0/0/0
NEW_RTR(config-if)#ip address 192.0.2.30 255.255.255.240

Requirement 6:
To enable interfaces
Use no shutdown command to enable interfaces
NEW_RTR(config-if)#no shutdown
NEW_RTR(config-if)#exit

Requirement 7:
Router protocol is RIPv2
Step 8:
Need to enable RIPv2 on router and advertise its directly connected networks
NEW_RTR(config)#router rip
To enable RIP v2 routing protocol on router use the command version 2
NEW_RTR(config-router)#version 2
Optional: no auto-summary (Since LAB networks do not have discontinuous networks)
RIP v2 is classless, and advertises routes including subnet masks, but it summarizes routes by default.
So the first things we need to do when configuring RIP v2 is turn off auto-summarization with the router command no auto-summary if you must perform routing between disconnected subnets.

NEW_RTR (config-router) # no auto-summary

Advertise the serial 0/0/0 and fast Ethernet 0/0 networks into RIP v2 using network command

NEW_RTR(config-router)#network 192.0.2.16
NEW_RTR(config-router)#network 209.165.202.128
NEW_RTR(config-router)#end

Step 9:
Important please do not forget to save your running-config to startup-config
NEW_RTR# copy run start
Any questions are welcomed on above LAB...
Best of Luck!!!!!

Hotspot 2: Topology Question

2007-12-18T09:37:00.000-08:00

640-802 CCNA Hotspot Topology Exhibit

Question 1:
Note: host 172.30.4.4 is wrongly given in Question the correct host must be 172.30.0.4

Answers: 702

Explanation:
The destination layer 2 address is a DLCI for frame-relay network. The destination host packet address is 172.30.0.4 corresponding DLCI is 702.
This can be confirmed by looking at the show frame-relay map output which shows the frame-relay map statements for layer 3 address to its corresponding layer 2 address IP 172.30.0.4 is mapped to DLCI 702 .

Question 2:

Answers: frame-relay map ip 172.30.0.3 196 broadcast

Explanation:

The show frame-relay map command above output provides the dynamic mapping for S-AMER (.3 as per topology the complete address is 172.30.0.3) to DLCI 196.

To create a static frame-relay map on dubai router to S-AMER we use the following command

Syntax: frame-relay map protocol protocol-address dlci [broadcast]

frame-relay map ip 172.30.0.3 196 broadcast

Question 3:

Answers: The serial connection to the MidEast branch office

Explanation:

By seeing the partial running config provided for Dubai router ... We can identify what encapuslation type is configured on each interface

Interface serial 1/0 : encapsulation frame-relay

Interface serial 1/2 and serial 1/3 : Both have encapsulation ppp

Interaface serial 1/1: Has no config info on encapsulation type this determines the default encapsulation (HDLC) is not changed on this interface.

Serial 1/1 is connection to MidEast branch office from Dubai router which has the default encapsulation.

Question 4:

Answers: No password is required.

Explanation: The serial connection between the mideast and Dubai router is having the default WAN encapsulation of HDLC. Since, HDLC requires no password to be set for connection establishment, "no password is required" is the correct answer.

Implement, verify, and troubleshoot NAT and ACLs

2007-11-17T03:34:00.000-08:00

CCNA (640-802) exam topic Implement, verify, and troubleshoot NAT and ACLs in a medium-size Enterprise branch office network .

Question1:
What are two reasons that a network administrator would use access lists? (Choose two.)
A:to control vty access into a router
B:to control broadcast traffic through a router
C:to filter traffic as it passes through a router
D:to filter traffic that originates from the router
E:to replace passwords as a line of defense against security incursions

Answers: A, C

Question 2:
Refer to the exhibit. The access list has been configured on the S0/0 interface of router RTB in the outbound direction. Which two packets, if routed to the interface, will be denied? (Choose two.)
access-list 101 deny tcp 192.168.15.32 0.0.0.15 any eq telnet
access-list 101 permit ip any any

A:source ip address: 192.168.15.5; destination port: 21
B:source ip address:, 192.168.15.37 destination port: 21
C:source ip address:, 192.168.15.41 destination port: 21
D:source ip address:, 192.168.15.36 destination port: 23
E:source ip address: 192.168.15.46; destination port: 23
F:source ip address:, 192.168.15.49 destination port: 23

Answers: D, E

Explanation:
access-list 101 deny tcp 192.168.15.32 0.0.0.15 any eq telnet
access-list 101 permit ip any any
The above two access-list statements are configured on RTB router and placed in outbound direction on S 0/0 interface.

First ACL statement denies all telnet ( port 23) connections from source address range 192.168.15.32 - 192.168.15.47 to any destination hosts.

Since we need to find the two packets that will be denied when routed outside s 0/0 interface .
source ip address:, 192.168.15.36 destination port: 23 this matches the ACL statement so this packet is denied.

source ip address: 192.168.15.46; destination port: 23 also matches the ACL statment so this packet is denied.

Question 3:
Refer to the exhibit. Why would the network administrator configure RA in this manner?

A: to give students access to the Internet
B: to prevent students from accessing the command prompt of RA
C: to prevent administrators from accessing the console of RA
D: to give administrators access to the Internet
E: to prevent students from accessing the Internet
F: to prevent students from accessing the Admin network

Answers: B

Explanation:
The above config entered on RA by administrator is to allow only Admin people (10.1.1.0) to access RA command prompt using telnet . Since there is an implicit deny any statement at the end of access-list 2, so rest all (students) are prevented from accessing command prompt of RA using telnet.

Question 4:
What is the function of the Cisco IOS command ip nat inside source static 10.1.1.5 172.35.16.5?
A: It creates a global address pool for all outside NAT transactions.
B: It establishes a dynamic address pool for an inside static address.
C: It creates dynamic source translations for all inside local PAT transactions.
D: It creates a one-to-one mapping between an inside local address and an inside global address. E: It maps one inside source address to a range of outside global addresses.

Answers: D

Explanation:
This command creates a static NAT translation entry for inside local address(10.1.1.5) to inside global address(172.35.16.5) .

Question 5:
What is the effect of the following access list condition?

access-list 101 permit ip 10.25.30.0 0.0.0.255 any

A: permit all packets matching the first three octets of the source address to all destinations
B: permit all packets matching the last octet of the destination address and accept all source addresses
C: permit all packets from the third subnet of the network address to all destinations
D: permit all packets matching the host bits in the source address to all destinations
E: permit all packets to destinations matching the first three octets in the destination address

Answers: A

Explanation:
The wild card mask (0.0.0.255) " 0's in wildcard mask needs a definite match" .

So for the above access-list wildcard mask specifies that it need to match first three octets of source address.

Destination address for the ACL is any so it permits all packets that matches the first three octets of source address to all destinations

Question 6:
What does the "Inside Global" address represent in the configuration of NAT?

A: the summarized address for all of the internal subnetted addresses
B: the MAC address of the router used by inside hosts to connect to the Internet
C: a globally unique, private IP address assigned to a host on the inside network
D: a registered address that represents an inside host to an outside network

Answers: D

Explanation:
Inside global address— A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world.

Question 7:
What three pieces of information can be used in an extended access list to filter traffic? (Choose three.)

A:protocol
B:VLAN number
C:TCP or UDP port numbers
D:source switch port number
E:source IP address and destination IP address
F:source MAC address and destination MAC address

Answers: A, C, E

Question 8:
An access list was written with the four statements shown in the graphic. Which single access list statement will combine all four of these statements into a single statement that will have exactly the same effect?

A: access-list 10 permit 172.29.16.0 0.0.0.255
B: access-list 10 permit 172.29.16.0 0.0.1.255
C: access-list 10 permit 172.29.16.0 0.0.3.255
D: access-list 10 permit 172.29.16.0 0.0.15.255
E: access-list 10 permit 172.29.0.0 0.0.255.255

Answers: C

Explanation:
To combine all four ACL statements into one ACL statement with same effect we need new network that matches all 4 statements network statement and new wildcard mask for the new network we will use.

New Network for the ACL statement: AND operation needs to be perform on all four statements.
AND operation: (AND: The output is true only when both inputs A and B are true.)

A - B = Output
0 -0 = 0; 0-1 = 0 ; 1-0 = 0; 1-1= 1
Following above AND operations procedure
172.29.16.0 = 10101100.00011101.00010000.00000000
172.29.17.0 = 10101100.00011101.00010001.00000000
172.29.18.0 = 10101100.00011101.00010010.00000000
172.29.19.0 = 10101100.00011101.00010011.00000000
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
172.29.16.0 = 10101100.00011101.00010000.00000000
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

new network after AND operation is 172.29.16.0

Now to find out Wildcard mask to match all four networks we need to perform XOR operations.

XOR operation: (XOR: The output is true when either inputs A or B are true, but not if both A and B are true.)

A - B = Output
0 - 0 = 0 ; 0 - 1 = 1 ; 1-0 = 1 ; 1 - 1 = 0

Following above XOR operations procedure
172.29.16.x = 10101100.00011101.00010000.x
172.29.17.x = 10101100.00011101.00010001.x
172.29.18.x = 10101100.00011101.00010010.x
172.29.19.x = 10101100.00011101.00010011.x
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
0.0.3.x = 00000000.00000000.00000011.x
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Since we are only concern about first three octets the last octet can be 255 so the new wildcard mask is 0.0.3.255

The complete single acl statement with new network and wildcard mask that matches all four networks is
access-list 10 permit 172.29.16.0 0.0.3.255

Question 9:
An inbound access list has been configured on a serial interface to deny packet entry for TCP and UDP ports 21, 23 and 25. What types of packets will be permitted by this ACL? (Choose three.)

A:FTP
B:Telnet
C:SMTP
D:DNS
E:HTTP
F:POP3

Answers: D, E, F

Explanation:
Ports 21, 23 and 25 are denied by ACL.
21 = FTP ; 23= Telnet ; 25= SMTP
Remaining ports are permited so DNS, HTTP and POP3 ports are permitted by ACL.

Quesstion 10:
Refer to the exhibit. The FMJ manufacturing company is concerned about unauthorized access to the Payroll Server. The Accounting1, CEO, Mgr1, and Mgr2 workstations should be the only computers with access to the Payroll Server. What two technologies should be implemented to help prevent unauthorized access to the server? (Choose two.)

A:access lists
B:encrypted router passwords
C:STP
D:VLANs
E:VTP
F:wireless LANs

Answers: A, D

Explanation:
Access-lists are created to permit only Accounting1, CEO, Mgr1, and Mgr2 workstations to Payroll server.
VLAN can be created which creates a separate Broadcast domain with vlan members only Accounting1, CEO, Mgr1, and Mgr2 workstations including Payroll server.

Question 11:
A network administrator would like to implement NAT in the network shown in the graphic to allow inside hosts to use a private addressing scheme. Where should NAT be configured?

A: Corporate router
B: Engineering router
C: Sales router
D: all routers
E: all routers and switches

Answers: A

Question 12:

An access list has been designed to prevent HTTP traffic from the Accounting Department from reaching the HR server attached to the Holyoke router. Which of the following access lists will accomplish this task when grouped with the e0 interface on the Chicopee router?

A: permit ip any any
deny tcp 172.16.16.0 0.0.0.255 172.17.17.252 0.0.0.0 eq 80
B: permit ip any any
deny tcp 172.17.17.252 0.0.0.0 172.16.16.0 0.0.0.255 eq 80
C: deny tcp 172.17.17.252 0.0.0.0 172.16.16.0 0.0.0.255 eq 80
permit ip any any
D: deny tcp 172.16.16.0 0.0.0.255 172.17.17.252 0.0.0.0 eq 80
permit ip any any

Answers: D

Explanation:.
We need to create a ACL which denies Account department network from accessing HTTP on HR server.

Source address is account department network: 172.16.16.0 mask 255.255.255.0
Destination address is HR server : 172.17.17.252
Port number for HTTP traffic on destination addresss : 80

First create deny statement
access-list 100 deny tcp 172.16.16.0 0.0.0.255 172.17.17.252 0.0.0.0 80

Since there is a implicit deny any any statement at the end of ACL we need to permit remaining traffic.
access-list 100 permit ip any any

Implement and verify WAN links

2007-11-17T01:11:00.000-08:00

CCNA (640-802) topic Implement and Verify WAN links answers the questions from this topic in exam.

Question 1:
A default Frame Relay WAN is classified as what type of physical network?
A: point-to-point
B: broadcast multi-access
C: nonbroadcast multi-access
D: nonbroadcast multipoint
E: broadcast point-to-multipoint

Answers: C

Question 2:
The command frame-relay map ip 10.121.16.8 102 broadcast was entered on the router. Which of the following statements is true concerning this command?
A: This command should be executed from the global configuration mode.
B: The IP address 10.121.16.8 is the local router port used to forward data.
C: 102 is the remote DLCI that will receive the information.
D: This command is required for all Frame Relay configurations.
E: The broadcast option allows packets, such as RIP updates, to be forwarded across the PVC.

Answers: E

Explanation:
When the frame-relay map command is included in the configuration with the broadcast keyword, it turns Frame Relay network as a broadcast network.

Question 3:
Refer to the exhibit. Which statement describes DLCI 17?

A: DLCI 17 describes the ISDN circuit between R2 and R3.
B: DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.
C: DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D: DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.

Answers: C

Question 4:
How should a router that is being used in a Frame Relay network be configured to avoid split horizon issues from preventing routing updates?
A: Configure a separate sub-interface for each PVC with a unique DLCI and subnet assigned to the sub-interface.
B: Configure each Frame Relay circuit as a point-to-point line to support multicast and broadcast traffic.
C: Configure many sub-interfaces on the same subnet.
D: Configure a single sub-interface to establish multiple PVC connections to multiple remote router interfaces.

Answers: A

Question 5:
What can a network administrator utilize by using PPP Layer 2 encapsulation? (Choose three.)
A:VLAN support
B:compression
C:authentication
D:sliding windows
E:multilink support
F:quality of service

Answers: B, C, E

Question 6:
Refer to the exhibit. What is the meaning of the term dynamic as displayed in the output of the show frame-relay map command shown?

A: The Serial0/0 interface is passing traffic.
B: The DLCI 100 was dynamically allocated by the router.
C: The Serial0/0 interface acquired the IP address of 172.16.3.1 from a DHCP server.
D: The DLCI 100 will be dynamically changed as required to adapt to changes in the Frame Relay cloud.
E: The mapping between DLCI 100 and the end station IP address 172.16.3.1 was learned through Inverse ARP.

Answers: E

Explanation:
Inverse ARP allows a Frame Relay network to discover the protocol address associated with the virtual circuit dynamically.

Question 7:
Which of the following describes the roles of devices in a WAN? (Choose three.)
A:A CSU/DSU terminates a digital local loop.
B:A modem terminates a digital local loop.
C:A CSU/DSU terminates an analog local loop.
D:A modem terminates an analog local loop.
E:A router is commonly considered a DTE device.
F:A router is commonly considered a DCE device.

Answers: A, D, E

Question 8:
Which three Layer 2 encapsulation types would be used on a WAN rather than a LAN? (Choose three.)
A:HDLC
B:Ethernet
C:Token Ring
D:PPP
E:FDDI
F:Frame Relay

Answers: A, D, F

Question 9:
The Frame Relay network in the diagram is not functioning properly. What is the cause of the problem?

A: The Gallant router has the wrong LMI type configured.
B: Inverse ARP is providing the wrong PVC information to the Gallant router.
C: The S3 interface of the Steele router has been configured with the frame-relay encapsulation ietf command.
D: The frame-relay map statement in the Attalla router for the PVC to Steele is not correct.
E: The IP address on the serial interface of the Attalla router is configured incorrectly.

Answers: D

Explanation:
In above exhibit we need to look at the status of each PVC to identify the problem.
At atlanta we find the show command for first Map status deleted. Which is the PVC to Steele because the next map statement in show command is for Gallant and its status is active.

Question 10:
Which of the following are key characteristics of PPP? (Choose three.)
A:can be used over analog circuits
B:maps Layer 2 to Layer 3 address
C:encapsulates several routed protocols
D:supports IP only
E:provides error correction

Answers: A, C, E

Question 11:
A Cisco router that was providing Frame Relay connectivity at a remote site was replaced with a different vendor's frame relay router. Connectivity is now down between the central and remote site. What is the most likely cause of the problem?
A: incorrect IP address mapping
B: mismatched encapsulation types
C: incorrect DLCI
D: mismatched LMI types

Answers: B

Question 12:
Refer to the exhibit. The network administrator must complete the connection between the RTA of the XYZ Company and the service provider. To accomplish this task, which two devices could be installed at the customer site to provide a connection through the local loop to the central office of the provider? (Choose two.)

A:WAN switch
B:PVC
C:ATM switch
D:multiplexer
E:CSU/DSU
F:modem

Answers: E, F

Question 13:
When a router is connected to a Frame Relay WAN link using a serial DTE interface, how is the interface clock rate determined?
A: It is supplied by the CSU/DSU.
B: It is supplied by the far end router.
C: It is determined by the clock rate command.
D: It is supplied by the Layer 1 bit stream timing.

Answers: A

Post a comment if you need explanation to any of the above questions!!!!!!

Topology Based Lab

2007-11-14T09:25:00.000-08:00

LAB QUESTION:

This topology contains 3 routers and 1 switch. Complete the topology.
Drag the appropriate device icons to the labeled Device
Drag the appropriate connections to the locations labeled Connections.
Drag the appropriate IP addresses to the locations labeled IP address (Hint: use the given host addresses and Main router information)
To remove a device or connection, drag it away from the topology.
Use information gathered from the Main router to complete the configuration of any additional routers. No passwords are required to access the Main router . The config terminal command has been disabled for the HQ router. The router does not require any configuration.

Configure each additional router with the following
Configure the interfaces with the correct IP address and enable the interfaces.
Set the password to allow console access to consolepw
Set the password to allow telnet access to telnetpw
Set the password to allow privilege mode access to privpw

Note: Because routes are not being added to the configurations, you will not be able to ping through the internetwork.
All devices have cable autosensing capabilities disabled.
All hosts are PC’s

ANSWER:

The question tells us that they are 3 routers and 1 Switch.

Drag the appropriate device icons to the labeled Device

Device Router (1) and Router (2) are connected to main router directly.
We can confirm this because the other Device labeled has Fa 0/2 and Fa 0/4 interfaces therefore this device is a switch.

Drag the appropriate connections to the locations labeled Connections.

1. The Main router is connected over serial link to Router (2) because on Router (2) the exhibit provide S 0/0 IP address icon towards Main router.

2. Router (1) is connected to Main router using a crossover cable. We require a crossover cable to connect two similar devices.

3. To connect host A directly to Router (1) fast ethernet 0/1 we need a crossover cable

4. Straight-through cable is used to connect a router (2) and switch together.

Drag the appropriate IP addresses to the locations labeled IP address (Hint: use the given host addresses and Main router information)

Host A IP address given 192.168.152.129 /28.
Host C IP address given 192.168.152.225 /28

/28 = 11111111. 11111111.11111111.11110000
= 255.255.255.240
Subnet mask is 255.255.255.240

Various subnet networks and its valid IP address ranges for the above subnet mask

1 – 15
16 – 31
32 – 47
48 – 63
64 – 79
80 – 95
96 – 111
112 -127
128 – 143 (Host A IP address is part of this subnet network IP address range, So Router (1)
Fa 0/1 address is 192.168.152.142)
144 – 159
160 – 175
176 – 191
192 – 207
208 – 223
224 – 239 (Host C IP address is part of this subnet network IP address range, Router (2)
Fa 0/0 address is 192.168.1.238)
240 – 255

Use the console of Main router and issue show running-config command at enable mode to verify the existing IP address configured on Main router Serial interface so has to identify the Network used in connecting Router (2) over serial link and depending on the network choose the appropriate IP address for S0/0 Router(2).

Similarly verify the Fast Ethernet interface IP address configuration on main router and select a IP address for Router (1) fa 0/0 it should be from same network address range.

Configure Router (1) and Router (2) with the following configuration:

Configure the interfaces with the correct IP address and enable the interfaces.
Router (1): Configuration

Router1>enable
Router1#configure terminal

Router1(config)#interface fa 0/0
Assigns IP address to Fa 0/0 and correct subnet mask
Router1(config-if)#ip address 192.168.152.190 255.255.255.240
Enables the interface
Router1(config-if)#no shutdown

Router1(config-if)#interface fa 0/1
Assigns IP address to Fa 0/1 and correct subnet mask
Router1(config-if)#ip address 192.168.152.142 255.255.255.240
Enables the interface
Router1(config-if)#no shutdown

Set the console, telnet and privilege mode access password as follows
Console: consolepw ; Telnet: telnetpw ; Privilege mode: privpw

To set console password

Router1(config)#line console 0
Router1(config-line)#password consolepw
Router1(config-line)#login
Router1(config-line)#exit

To set telnet password
Router1(config)#line vty 0 4
Router1(config-line)#password telnetpw
Router1(config-line)#login
Router1(config-line)#exit

To set privilege mode password

Router1(config)#enable password privpw

Router (2): Configuration

Router2>enable
Router2#configure terminal

Router2(config)#interface fa 0/0
Assigns IP address to Fa 0/0 and correct subnet mask
Router2(config-if)#ip address 192.168.152.238 255.255.255.240
Enables the interface
Router2(config-if)#no shutdown

Router2(config-if)#interface serial 0/0
Assigns IP address to serial 0/0 and correct subnet mask
Router2(config-if)#ip address 192.168.152.174 255.255.255.240
Enables the interface
Router2(config-if)#no shutdown

Set the console, telnet and privilege mode access password as follows
Console: consolepw ; Telnet: telnetpw ; Privilege mode: privpw

Similar configuration needs to be done for Router (2) to set the passwords for console, telnet and privilege mode as we did for Router(1).

Hotspot: Topology Based Questions

2007-11-12T10:11:00.001-08:00

Question 1:
If router has a packet destination address 192.168.1.255. What describes the operation of the network?

Answer:
R1 will drop this packet because it is not a valid ip address

Explanation:

The destination IP address 192.168.1.255 is broadcast address of the network 192168.1.0 /24 on router R1.

Network Address: 192.168.1.0 subnet mask: 255.255.255.0

Network valid host range: 192.168.1.1 – 192.168.1.254

Broadcast Address : 192.168.1.255

Since router (R1) received a packet with destination IP address (192.168.1.255) which is broadcast address so it simply discards the packet as Forwarding broadcast packet can lead to severe storms of packets, and if uncontrolled could lead to network overload.

Question 2:
Users on the 192.168.1.0 /24 network must access files located on the server 1. What route could be configured on router R1 for the file requests to reach the server ?

Answer:
ip route 0.0.0.0 0.0.0.0 s 0/0/0

Explanation:
To enable users on 192.168.1.0 network to access files on server1, we need to establish a default static route.

Static route syntax:
ip route prefix mask {ip-address interface-type interface-number [ip-address]} [distance] [name] [permanent track number] [tag tag]

From the options provided for this question the correct default static route is
ip route 0.0.0.0 0.0.0.0 S 0/0/0

PS: As per best practices static route to server1 on R1 should have been

ip route 209.165.200.0 255.255.255.0 209.165.100.200
(or)
ip route 209.165.200.0 255.255.255.0 s 0/0/0

Question 3:
When a packet is sent from Host1 to Server1,in how many different frames will the packet be encapsulated as it is sent across the internetwork?

Answer:
3

Explanation:

First: Host1 encapsulates the packet into frames and forwards to the switch.
Switch in turn forwards the same frame to router R1.

Second: Router R1 receives the frame on one interface and it is encapsulates into new packet once it leaves the router R1 towards the direction of server1.

Third: R2 receives this packet and it also encapsulates the frame into new packet when it is forwarded to server1 on different interface of R2.

Therefore the packet is sent using three different frames to reach from Host1 to server1.

Question 4:
What must be configured on the network in order for users on the internet to view web pages located on web server2?

Answer:
On router R1, configure a NAT to translate address on 209.165.100.0 to 192.168.1.0 network.

Question 5:
The router address 192.168.1.250 is the default gateway for both web server2 and host 1. What is the correct subnet mask for this network?

Answer:
255.255.255.0

Explanation:
Given subnet mask for this network is 255.255.255.0 based on the exhibit.
To find the correct subnet mask for this network based on number of devices shown in the exhibit that are already configured with IP address and by not wasting IP addresses scheme.

The network 192.168.1.0 consists of only three devices as per the exhibits which are configured with IP address.

R1(fa 0/0) : 192.168.1.250 ( default gateway as per the question)
Host1: 192.168.1.10
Web server 2: 192.168.1.106

correct subnet mask that will cover all above IP address is 255.255.255.0
( Thanks to Helmut who identified the exhibit IP address to be considered for this selection of correct subnet mask)

Knowledge Base for NAT SIM:

2007-11-05T07:36:00.000-08:00

Inside local address—The IP address assigned to a host on the inside network. This is the address configured as a parameter of the computer OS or received via dynamic address allocation protocols such as DHCP. The address is likely not a legitimate IP address assigned by the Network Information Center (NIC) or service provider.

Inside global address— A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world.

Command: ip nat pool
To define a pool of IP addresses for Network Address Translation (NAT), use the ip nat pool command in global configuration mode. To remove one or more addresses from the pool, use the no form of this command.

Syntax:
ip nat pool name start-ip end-ip {netmask netmask prefix-length prefix-length}[type rotary]
no ip nat pool name start-ip end-ip {netmask netmask prefix-length prefix-length} [type rotary]

Usage Guidelines: ip nat pool

This command defines a pool of addresses using start address, end address, and either netmask or prefix length. The pool could define either an inside global pool, an outside local pool, or a rotary pool.

Command: ip nat inside source
To enable Network Address Translation (NAT) of the inside source address, use the ip nat inside source command in global configuration mode. To remove the static translation or remove the dynamic association to a pool, use the no form of this command.

Syntax:
ip nat inside source {list {access-list-number access-list-name} route-map name} {interface type number pool name} [mapping-id map-name vrf name] [overload]

Usage Guidelines: ip nat inside source
This command has two forms: dynamic and static address translation. The form with an access list establishes dynamic translation. Packets from addresses that match the standard access list are translated using global addresses allocated from the pool named with the ip nat pool command.

Packets that enter the router through the inside interface and packets sourced from the router are checked against the access list for possible NAT candidates. The access list is used to specify which traffic is to be translated.

Alternatively, the syntax form with the keyword static establishes a single static translation.

NAT SIM QUESTION

CCNA 640-802: NAT SIM

2007-11-05T07:26:00.000-08:00

Question:
A network associate is configuring a router for the weaver company to provide internet access. The ISP has provided the company six public IP addresses of 198.18.184.105 198.18.184.110. The company has 14 hosts that need to access the internet simultaneously. The hosts in the company LAN have been assigned private space addresses in the range of 192.168.100.17 – 192.168.100.30 .

CLICK ON IMAGE TO VIEW

Click Knowledge Base for NAT SIM to learn the concepts before attempting or learning this SIM Question

NAT SIM Configuration:

The following configuration translates between inside hosts (Weaver LAN) addressed from 192.168.100.16 /28 network (192.168.100.17 – 192.168.100.30) to the globally unique pool of address provided by ISP 198.18.184.105 – 198.18.184.110 /29.

Weaver>enable
Weaver#configure terminal

Before starting the NAT configuration verify that router hostname currently configured is weaver. If not change hostname to Weaver using the command

Router(config)#hostname weaver

Step1: Create an access-list to match all the Weaver LAN address that need to be the candidates for NAT translations

Weaver(config)#access-list 10 permit 192.168.100.16 0.0.0.15

Step2: Create a NAT Pool with pool name isp_adr and specify the pool address range provided by ISP with their netmask.

Weaver(config)#ip nat pool isp_adr 198.18.184.105 198.18.184.110 netmask 255.255.255.248

Step3: Packets that match access-list 10 will be translated to an address from the pool called "isp_adr".

Overload keyword specify to use Port based NATing to support all the Weaver LAN address range.

Weaver(config)#ip nat inside source list 10 pool isp_adr overload

SIM Question already provides that appropriate interfaces have been configured for NAT Inside and NAT Outside statements.

For your information configuration would have been like this

Weaver(config)#interface fastethernet 0/0
Weaver(config-if)#ip nat inside

Weaver(config)#interface serial 0/0
Weaver(config-if)#ip nat outside

Functionality Test:
Our requirements are to allow the hosts (Weaver LAN) the ability to communicate with the Internet. For this test, we ping the Internet device (ISP router S0/1) from Host for testing.

Step1:
Go to host for testing:
C:\>ping 192.0.2.114

PING should be success to 192.0.2.114 since SIM question provides that static route is already configured on router.

Step2:
On console of router (Weaver) :
Issue show ip nat translation command to verify the NAT translations.

Sample output:
Considering host for testing IP address is 192.168.100.17

weaver# show ip nat translation

Pro Inside global Inside local Outside local Outside global
icmp 198.18.184.105:434 192.168.100.17:434 192.0.2.113:434 192.0.2.114:434
icmp 198.18.184.105:435 192.168.100.17:435 192.0.2.113:435 192.0.2.114:435
icmp 198.18.184.105:436 192.168.100.17:436 192.0.2.113:436 192.0.2.114:436
icmp 198.18.184.105:437 192.168.100.17:437 192.0.2.113:437 192.0.2.114:437
icmp 198.18.184.105:438 192.168.100.17:438 192.0.2.113:438 192.0.2.114:438

Any Questions on SIMULATOR welcomed.
Best of LUCK to your CCNA EXAM

QUICK NOTES - CCNA

2007-07-01T09:05:00.000-07:00

CCNA QUICK NOTES

CCNA Quick notes provides a last minute preparation before your CCNA EXAM.
Select a topic below for specific notes.

1. LAN
2. WAN
3. INTERNETWORKING
4. CABLING DEVICES
5. ACCESS LISTS
6. FRAME RELAY
7. ROUTING
8. SWITCHING
9. NETWORK MANAGEMENT
10. IOS COMMANDS
11. PPP
12. ISDN
13. VLANS
14. TCP /IP

I am currently working on this blog!!!!

Quick Notes - VLANS

2007-07-01T08:37:00.000-07:00

What are VLANs?
VLANs are broadcast domains in a Layer 2 network. Each broadcast domain is like a distinct virtual bridge within the switch. Each virtual bridge you create in a switch defines a broadcast domain. By default, traffic from one VLAN cannot pass to another VLAN. Each of the users in a VLAN is also in the same IP subnet, and each switch port can belong to only one VLAN.

What are the three characteristics of a typical VLAN setup?
The three characteristics of a typical VLAN setup are:
Each logical VLAN is like a separate physical bridge.
VLANs can span multiple switches.
Trunks carry traffic for multiple VLANs.

What are trunk links?
By default, each port on a switch can belong to only one VLAN. For devices that are in VLANs (that span multiple switches) to talk to other devices in the same VLAN, you must use trunking or have a dedicated port per VLAN. Trunk links allow the switch to carry multiple VLANs across a single link.

What are the two methods you can use to assign a port to a VLAN?
The two methods to assign a port to a VLAN are
Statically
Dynamically

What is Inter-Switch Link (ISL)?
ISL is a Cisco proprietary protocol used to interconnect switches that have multiple VLANs. It maintains VLAN information as traffic goes between switches, allowing the traffic to enter the correct VLAN. ISL operates in a point-to-point environment.

At which layer of the OSI model does ISL function?
ISL functions at Layer 2 of the OSI model. It encapsulates a data frame with a new ISL header and CRC. Because ISL operates at Layer 2 of the OSI model, it is protocol-independent.

What type of tagging method does ISL use?
Many network professions refer to the way ISL tags frames as an external tagging mechanism. This is because ISL encapsulates each frame and does not modify the original packet.
Many network professions refer to the way ISL tags frames as an external tagging mechanism. This is because ISL encapsulates each frame and does not modify the original packet.

How many extra bytes does ISL add to an existing Ethernet frame?
ISL adds a 26-byte ISL header and a 4-byte CRC to each frame, extending each Ethernet frame by 30 bytes. ISL tagging is implemented in ASICs, so tagging is done at wire speed.

What is VTP?
VLAN Trunking Protocol (VTP) is a Layer 2 messaging protocol that maintains VLAN configuration consistency throughout a common administrative domain by managing VLANs' additions, deletions, and name changes across multiple switches. Without VTP, you would have to add VLAN information in all switches in your network.

What is a VTP domain?
A VTP domain is one or more interconnected switches that share the same VTP environment. A switch can be in only one VTP domain, and all VLAN information is propagated to all switches in the same VTP domain.

What are the three VTP modes?
The three VTP modes are
Server
Client
Transparent

What is VTP server mode?
A switch in VTP server mode can add, delete, and modify VLANs and other configuration parameters for the entire VTP domain. This is the default mode for all Catalyst switches. VLAN configurations are saved in NVRAM. When you change VLAN configuration in server mode, the change is dynamically propagated to all switches in the VTP domain.

What is VTP client mode?
In VTP client mode, a switch cannot create, delete, or modify VLANs. Also, a VTP client does not save VLAN information and configuration in NVRAM. In client and server mode, VLAN information is synchronized between switches in the VTP domain.

What is VTP transparent mode?
In transparent mode, a switch can add, modify, and delete VLANs. This information is not transmitted to other switches in the VTP domain. They affect only the local switch. VTP transparent mode is used when a switch does not need to participate in the VTP domain but needs to propagate VTP information to other switches.

How often are VTP advertisements flooded throughout the management domain?
VTP advertisements are flooded throughout the management domain every 5 minutes or whenever a change occurs in VLAN configuration.

What is included in VTP advertisements?
VTP advertisements include the following:
VTP revision number
VLAN names and numbers
Information about switches that have ports assigned to each VLAN

What is one of the most important components of the VTP advertisement?
The revision number is one of the most important components of the VTP advertisement. Every time a VTP server modifies its VLAN configuration, it increments the configuration number by 1. The largest configuration number in the VTP domain contains the most current information. When a client receives a revision number higher than its current number, it updates its VLAN configuration.

On a Catalyst 1900 switch, how do you reset the configuration number?
To reset the configuration numbers on a Catalyst 1900, use the delete vtp privileged EXEC command, and then reset the switch.

What is VTP pruning?
By default, a trunk link carries traffic for all VLANs in the VTP domain. Even if a switch does not have any ports in a specific VLAN, traffic for that VLAN is carried across the trunk link. VTP pruning uses VLAN advertisements to determine when a trunk connection is needlessly flooding traffic to the trunk links that the traffic must use to access the appropriate network device.

How many VLANs with a separate spanning tree per VLAN does the Catalyst 1900 support?
The Catalyst 1900 supports 64 VLANs with a separate spanning tree per VLAN.

What VLAN number are CDP and VTP advertisements sent across?
CDP and VTP advertisements are sent on VLAN 1, which is also known as the management VLAN.

What must you remember before you create VLANs on a Catalyst switch?
Before you create VLANs on a Catalyst 1900 switch, the switch must be in VTP server mode or VTP transparent mode.

How do you configure the VTP operation mode on a Catalyst 1900?
To configure VTP on a Catalyst 1900, use the vtp [server transparent client] global configuration command:

Cat1900(config)#vtp server

How do you configure a VTP domain on a Catalyst 1900 switch?
To configure a VTP domain on a Catalyst 1900 switch, use the vtp domain domain-name global command:

Cat1900(config)#vtp domain cisco

How do you configure a VTP domain password on a Catalyst 1900?
Use the vtp password password global command to configure a VTP domain password. This example sets the VTP password to cisco:

Cat1900(config)#vtp password cisco

What does the show vtp privileged EXEC command display?
The show vtp privileged EXEC command displays the following:
VTP version
The number of existing VLANs on a switch and the maximum number of locally supported VLANs
VTP domain name, password, and operating mode
Whether VTP pruning is enabled
The last time VLAN configuration was modified.
Here's an example of show vtp output:

Cat1900#show vtp

VTP version: 1

Configuration revision: 0

Maximum VLANs supported locally: 1005

Number of existing VLANs: 5

VTP domain name : cisco

VTP password : cisco

VTP operating mode : Server

VTP pruning mode : Disabled

VTP traps generation : Enabled

Configuration last modified by: 192.168.0.2 at 00-00-0000 00:00:00

What command do you use to add a VLAN on a Catalyst switch?
To add a VLAN on a Catalyst switch, use the vlan vlan-number [name vlan_name] global command. The following example adds VLAN 10 with a name of Sales: Cat1900(config)#vlan 10 name Sales

What Catalyst 1900 command can you use to verify VLAN information?
To verify VLAN information, use the show vlan vlan-number privileged EXEC command.

How do you view spanning tree information for a particular VLAN?
A Catalyst 1900 switch can have a maximum of 64 VLANs with a separate instance of spanning tree per VLAN. To view spanning tree information for a particular VLAN use the "show spandtree vlan-id" command.

QUICK NOTES HOME

Quick Notes - TCP / IP

2007-07-01T08:07:00.000-07:00

What are the four layers of the TCP/IP layer model?
The four layers of the TCP/IP layer model are:
Application (process)
Host-to-host (transport)
Internet
Network Access (physical and data link)

What two protocols function at the transport (host-to-host) layer of the TCP/IP model?
The two protocols that function at the host-to-host layer of the TCP/IP model are TCP and UDP. (TCP is a connection-oriented, reliable protocol. UDP is a connectionless and unacknowledged protocol.)

What are the protocol numbers for TCP and UDP?
The protocol number for TCP is 6. The protocol number for UDP is 17.

How many bytes are in the header for TCP and UDP packets?
A TCP header contains 20 bytes, and a UDP header contains 8 bytes.

What are TCP and UDP port numbers?
To pass information (such as e-mail) to upper layers, TCP and UDP use port numbers. These port numbers are used to keep track of different conversations among different hosts at the same time. Originating source port numbers are dynamically assigned by the source host, which is a number greater than 1023.

What is the number range for "well-known" port numbers?
Defined in RFC 1700, the well-known port numbers are 1 to 1023.

What are the steps for the TCP three-way handshake?
The steps for the TCP three-way handshake are as follows:
Step 1. The source host sends a SYN to the destination host.
Step 2. The destination host replies with a SYN/ACK to the source host.
Step 3. The source host replies with an ACK.

What are some protocols that operate at the TCP/IP Internet layer?
Some protocols that operate at the TCP/IP Internet layer are
IP
ICMP
ARP
RARP

What is the Internet Protocol (IP)?
IP is a connectionless protocol that provides best-effort delivery routing of datagrams.

What is the Internet Control Message Protocol (ICMP)?
ICMP is a management protocol for IP. ICMP messages are carried in IP datagrams and are used to send error and control messages. An example of a utility that uses ICMP is ping.

What is the Address Resolution Protocol (ARP)?
ARP is used to resolve a known IP address to a MAC address. In order for a host to communicate with another host, it must know the MAC address of the destination host (if they are on the same network) or next hop router. This is the reason for ARP.

What is the Reverse Address Resolution Protocol (RARP)?
RARP is a protocol used to find the IP address of a station that knows its MAC address. It is mainly used for diskless workstations that boot up and need an IP address. An RARP request is a broadcast packet.

What are the IP address ranges for Class A, Class B, and Class C addresses?
The address ranges are as follows: Class A 1.0.0.0 to 126.0.0.0Class B 128.0.0.0 to 191.255.0.0Class C 192.0.0.0 to 223.255.255.0

What does RFC 1918 define?
RFC 1918 defines reserved (private) networks and addresses that are not routed on the Internet. These addresses are 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to 192.168.255.255. They are used as internal private addresses. Private addresses are widely used today, along with proxy servers and Network Address Translation to assist with "stretching" the current IP address space.

Cisco IOS software supports what three kinds of broadcasts?
The three kinds of broadcasts that Cisco IOS software supports are:
Flooding
Directed broadcast
All-subnet broadcast
Flooded broadcasts are local broadcasts that have an address of 255.255.255.255. They are not propagated by a router.
Direct broadcasts are directed to a specific network. They contain all 1s in the host portion of the address. Routers forward these broadcasts. An example is 192.168.0.255/24.
All-subnet broadcast are broadcast messages to all hosts within a subnet and to all subnets within a network. An example is 192.168.255.255/24. With Cisco IOS release 12.0, a router does not forward all subnet broadcasts. You can use the ip directed-broadcast command to enable all subnet broadcasts.

How do you assign an IP address to a Cisco router?
To assign an IP address to a router, use the ip address address subnet-mask interface configuration command. Here's an example:

RouterB(config)#inter e0

RouterB(config-if)#ip address 172.16.0.1 255.255.0.0

RouterB(config-if)#no shut
Note: By default all interfaces on a Cisco router are administratively disabled. To enable them you must use the "no shut" interface command.

How do you manually assign IP addresses to host names in a Cisco router?
The ip host name [tcp-port-number] address [address] global configuration command lets you assign IP addresses to host names in a Cisco router. [tcp-port-number] is an optional parameter; the default value is Telnet. Here's an example:

RouterB(config)#ip host cisco 172.16.0.1

What Cisco IOS command can you use to program the router to use a DNS server to resolve host names?
The ip name-server server-address [[server-address2]...[server-address6]] command lets you program the Cisco router to resolve host names with a DNS server. Here's an example:

RouterB(config)#ip name-server 172.16.0.250

If you enter a command that a Cisco router does not recognize, the router tries to resolve the command you just entered with a DNS server. How do you turn off this DNS domain lookup?
To turn off DNS domain lookup, use the no ip domain-lookup global command. Here's an example: RouterB#enb

Translating "enb"...domain server (255.255.255.255)% Unknown command or computer name, or unable to find computer address

RouterB#config t

Enter configuration commands, one per line. End with CNTL/Z.

RouterB(config)#no ip domain-lookup

For different VLANs to communicate with each other, they need to be routed (a router!). To perform inter-VLAN routing, what two things must occur?
To perform inter-VLAN routing, the following must occur:
The router must know how to reach all VLANs being interconnected.
The router must have a separate physical connection on the router for each VLAN, or trunking must be enabled on a single physical connection.

How do you enable ISL trunking on a Cisco router?
To enable ISL trunking on a Cisco router, you must do the following:
Step 1 Configure subinterfaces on the router's physical Fast Ethernet or Gigabit interface. (ISL trunking works only on Fast Ethernet or Gigabit interfaces.)
Step 2 Assign an IP address to the subinterface.
Step 3 Enable ISL encapsulation for the particular VLAN with the encapsulate isl vlan# subinterface command.
Here's an example:

RouterB(config)#int f0/0

RouterB(config-subif)#ip address 172.16.0.1 255.255.0.0

RouterB(config-subif)#encapsulation isl 1

QUICK NOTES HOME

Quick Notes - SWITCHING

2007-07-01T05:27:00.000-07:00

What are three types of LAN traffic?
Unicasts - intended for one host.
Broadcasts - intended for everyone.
Multicasts - intended for a only a subset or group within an entire network.

What are unicast frames?
Unicast frames are the most common type of network traffic. A unicast frame is a frame intended for only one host. The only station that processes this frame is one station that has its own MAC address in the destination portion of packet.

What are broadcast frames?
Broadcast frames are frames intended for everyone. Stations view broadcast frames as public service announcements. All stations receive and process broadcast frames. In large networks, broadcasts can cause serious performance degradation in network hosts - (broadcast storm).
The destination address of broadcast frames (Data Link / Layer 2 broadcast addresses is FF-FF-FF-FF-FF-FF or alternatively all 1s in binary (11111111).

What are multicast frames?
Multicast frames address a group of devices that have a common interest. These frames allow the source to send only one copy of the frame on the network even though it is intended for several stations. Only stations that have a card that is configured by software to receive multicast frames for a particular multicast group can process a frame to that multicast address - all other stations discard multicast frames. An example of a multicast frame is: 01:00:5E:01:01:01/ The "01" at the beginning of the address signifies that it is an Ethernet multicast frame.

What three major functions do Data Link Layer / Layer 2 Switches perform?
Address learning
Packet forwarding/filtering
Loop avoidance by spanning tree

What will occur when you attempt to segment a network with hubs and repeaters?
Basically, hubs and repeaters become extensions of the physical cable plant. All devices that connect to either a hub or a repeater share the same bandwidth and by definition hubs and repeaters create a single broadcast and collision domain.
Think of both devices are pass-through devices much like a electrical power-strip. Hubs and repeaters reside on the Physical Layer / Layer 1 of the OSI model where they pass 0s and 1s along the wire or up to the Data Link Layer. CSUs / Channel Service Units fall into the same category. All are regarded as unintelligent devices. No addressing takes place on the Physical layer.

What is the advantage of segmenting a network with bridges or switches?
Bridges and switches function on the Data Link Layer / Layer 2 of the OSI model and filter by MAC address. Each port on either device provides full, dedicated bandwidth and creates a single collision domain.
Very important:
Because bridges and switches operate a Layer 2 -- they cannot filter broadcasts, and they create a single broadcast domain. (Note: each nailed-up port on a switch is a single Collision Domain - there will be a schematic on the exam to test your knowledge on broadcast and collision domains.)
Also, bridges are implemented by software and normally have a couple of network ports; whereas switches are implemented in hardware by ASIC chips and have many ports.
Think Data Link Layer / Layer 2 of the OSI model - physical addresses / MAC addresses
List some advantages Layer 2 switches have over bridges:
· High-speed backplane - multiple simultaneous conversations.
· Data-buffering capabilities are used to store-and-forward packets to the correct port(s).
· Lower latency than bridges. Remember that switches are implemented in hardware not software. Much faster.
· Higher port count or density.

What are the pros can cons of segmenting a LAN with routers?

Pros: Each interface on a router creates a single broadcast and collision domain. Routers function or operate on the Network Layer / Layer 3 of the OSI model and do not propagate broadcasts*. (* very important concept)

Cons: Routers are not transparent and are implemented in software thereby introducing latency in the network.

Remember: Routers = Network Layer / Layer 3 on the OSI model - Logical addressing (IP address).

Functions: Two key functions: routing and switching. The routing component is responsibile for learning and maintaining awareness of the network topology. The switching function is the process of moving packets from an inbound interface (Ethernet 0 for example) to an outbound interface (Serial 0 for example). Path selection is a key term.

What three devices are used to segment a LAN?
Router - logical addressing - IP address
Switch - physical addressing - MAC address
Bridge - physical addressing - MAC addres

What is microsegmentation?
Each workstation or network device on the network has its own dedicated segment - also known as a Collision Domain - to a switch. Each device gets the segments full bandwidth and does not have to share the dedicated segment with other devices. Collisions are reduced because each segment is its own Collision Domain.

Important: Full-duplex transmission is achieved by microsegmentation. Each device can send and receive at the same time which doubles the amount of bandwidth between nodes.

What are the three switching methods in Cisco Catalyst switches?
The three frame operating modes to handle frame switching are
Store-and-forward
Cut-through
Fragment-free

What is the Cisco Catalyst store-and-forward switching method?
In the store-and-forward switching method, the switch receives the entire frame before it forwards it. The switch reads the cyclic redundancy check (CRC) to make sure the frame is not bad. If the frame is good, the switch forwards it. Because the switch stores the frame before forwarding it, latency is introduced in the switch. Latency through the switch varies with the size of the frame.

What is the Cisco Catalyst cut-through switching method?
In cut-through switching mode, the switch only checks the frame's destination address and immediately begins forwarding the frame out the appropriate port. Because the switch checks the destination address in only the header and not the entire frame, the switch forwards a collision frame or a frame that has a bad CRC.

What is the Cisco Catalyst fragment-free switching method?
Also known as modified cut-through, fragment-free switching checks the first 64 bytes before forwarding the frame. Ethernet specifications state that collisions should be detected during the first 64 bytes of the frame. By reading the first 64 bytes of the frame, the switch can filter most collisions, although late collisions are still possible.

What is the default switching mode in Cisco Catalyst 1900 switches?
The default switching mode for the Catalyst 1900 is fragment-free.

What is half-duplex transmission mode?
Half-duplex transmission is the default mode that Ethernet functions in. In half-duplex transmission, a device can only send or receive--not do both at once. In half-duplex mode, stations are susceptible to collisions, and efficiency is rated at 50 to 60 percent.

What is full-duplex transmission mode?
In full-duplex mode, a station can send and receive at the same time. In full-duplex mode, collision detection is disabled. This mode offers 100 percent efficiency in both directions.
On a Cisco Catalyst 1900 switch, what are the default duplex settings for 10BaseT/100BaseT ports, default switching mode, and default protocols?
The factory default settings for a Catalyst 1900 switch are as follows: · IP address: 0.0.0.0· CDP enabled· Switching mode: fragment-free· 10BaseT ports: half-duplex· 100BaseT ports: autonegotiate· Spanning tree enabled· No console password

What are the two configuration modes in a Catalyst 1900 switch?
Configuring a Catalyst 1900 switch is similar to configuring a router. The two configuration modes available are global configuration mode and interface configuration mode.

How do you configure an IP address and subnet mask on a Catalyst 1900 switch?
To configure an IP address and subnet mask on a Catalyst 1900 switch, use the ip address address mask global configuration command:

Cat1900(config)#ip address 192.168.0.2 255.255.255.0

Why would you want to assign an IP address to a Layer 2 device, such as a switch?
You would assign an IP address to a Layer 2 device for management and configuration. With an IP address enabled on a Cisco switch, you can Telnet into it and change the configuration. You can also enable SNMP on the device and remotely monitor the switch.

How do you configure a default gateway on a Cisco Catalyst 1900 switch?
To configure a default gateway on a Catalyst 1900 switch, use the ip default-gateway ip address global configuration command. The following example configures the switch to use IP address 192.168.0.1 as its default gateway:

Cat1900(config)#ip default-gateway 192.168.0.1
To remove the default gateway, use the no ip default-gateway command.

On a Catalyst 1900 switch, what command can you use to view the switch's IP address, subnet mask, and default gateway?
The show ip command displays the switch's IP address, subnet mask, and default gateway. Here's an example:

Cat1900#show ipIP Address: 192.168.0.2

Subnet Mask: 255.255.255.0

Default Gateway: 192.168.0.1

Management VLAN: 1

Domain name:

Name server 1: 0.0.0.0

Name server 2: 0.0.0.0

HTTP server : Enabled

HTTP port : 80

RIP : Enabled

Cat1900#

How do you change the duplex mode on a Catalyst 1900 switch?
To change the duplex mode on a Catalyst 1900 switch, use this command:
duplex {auto full full-flow-control half}
The following example changes the duplex speed for Ethernet interface 1 on the switch to full duplex:

Cat1900(config)#interface e0/1

Cat1900(config-if)#duplex full

How do you change the duplex mode on a Catalyst 1900 switch?
To change the duplex mode on a Catalyst 1900 switch, use this command:
duplex {auto full full-flow-control half}
The following example changes the duplex speed for Ethernet interface 1 on the switch to full duplex:

Cat1900(config)#interface e0/1

Cat1900(config-if)#duplex full

What command can you use to view the duplex settings and spanning tree state of a Catalyst switch?
You use the show interface type module/port EXEC command to view the duplex settings and spanning tree state. This example shows the output for the show interface command on Ethernet interface 0/1:

Cat1900#show interface e0/1

Ethernet 0/1 is Suspended-no-link

beatHardware is Built-in 10Base-TAddress is 0010.F621.F681MTU 1500 bytes, BW 10000 Kbits802.1d

STP State: Forwarding

Forward Transitions: 1

Port monitoring: Disabled

Unknown unicast flooding: Enabled

Unregistered multicast flooding: Enabled

Description:Duplex setting: Full duplex

Back pressure: Disabled

What command can you use to check for frame check sequence (FCS) or late collision errors?
The show interface type module/port EXEC command displays FCS or late collision errors. Cat1900#show interface e0/1

Receive Statistics Transmit Statistics

------------------------------------- -------------------------------------

Total good frames 0 Total frames 0Total octets 0 Total octets 0

Broadcast/multicast frames 0 Broadcast/multicast frames 0Broadcast/multicast octets 0 Broadcast/multicast octets 0Good frames forwarded 0 Deferrals 0Frames filtered 0 Single collisions 0 Runt frames 0 Multiple collisions 0No buffer discards 0 Excessive collisions 0 Queue full discards 0Errors: Errors: FCS errors 0 Late collisions 0 Alignment errors 0 Excessive deferrals 0 Giant frames 0 Jabber errors 0 Address violations 0 Other transmit errors 0

How do you display the MAC address table on a Catalyst 1900 switch?
The show mac-address-table EXEC command displays the MAC address table and also tells you whether the MAC address entry is dynamic, permanent, or static. Here's an example: Cat1900#show mac-address-table

Address Dest Interface Type Source Interface List

----------------------------------------------------------------------

0080.C6E7.9CEF Ethernet 0/21 Dynamic All0030.80EF.988C Ethernet 0/22 Dynamic All

0040.05A2.5E92 Ethernet 0/11 Dynamic All

What are dynamic addresses on a Catalyst switch?
Dynamic addresses are addresses that the switch learns about dynamically through the learning process. If the switch does not see a MAC address for a certain amount of time, it drops the MAC address.

What are permanent MAC addresses on a Catalyst switch?
Permanent MAC addresses are entered manually by the administrator and are not aged out.

On a Catalyst 1900 switch, how do you make a MAC address permanent?
To make a MAC address permanent, use the mac-address-table permanent mac-address type module/port global command. The following example makes MAC address 0080.C6E7.9CEF permanent in the CAM table for port 0/21:

Cat1900(config)#mac-address-table permanent 0080.C6E7.9CEF Ethernet 0/21

What is the maximum number of MAC addresses a Catalyst 1900 can store in its MAC address table?
The maximum number of MAC addresses a Catalyst 1900 can store in its MAC address table is 1024.

What are static MAC addresses in a Catalyst 1900 switch?
On a Catalyst 1900 switch, static addresses allow you to restrict a MAC address to a specific port.

How do you restrict a MAC address to a specific port on a Catalyst 1900 switch?
To restrict a MAC address to a specific port, use the mac-address-table restricted static mac-address type module/port src-if-list global command:

Cat1900(config)#mac-address-table restricted static aaaa.aaaa.aaaa e0/1
This restricts MAC address aaaa.aaaa.aaaa to Ethernet port 0/1.

What EXEC command can you use to show the port security configurations on a Catalyst 1900 switch?
The show mac-address-table security command displays the port security configurations: Cat1900#show mac-address-table security

Action upon address violation : Suspend Interface Addressing Security Address Table Size Clear Address

-------------------------------------------------------------------------------

Ethernet 0/1 Disabled N/A NoEthernet 0/2 Disabled N/A NoEthernet 0/3 Enabled 100 NoEthernet 0/4 Disabled N/A NoEthernet 0/5 Disabled N/A NoEthernet 0/6 Disabled N/A NoEthernet 0/7 Disabled N/A NoEthernet 0/8 Disabled N/A NoEthernet 0/9 Disabled N/A No

What Catalyst command can you use to display information about the IOS software version and hardware information about the switch?
The show version EXEC command displays the IOS software version and hardware information about the switch. The following example shows the output of the show version command on a Catalyst switch:

Cat1900#show version

Cisco Catalyst 1900/2820 Enterprise Edition SoftwareVersion V9.00.04 written from 192.168.000.001Copyright (c) Cisco Systems, Inc. 1993-1999Cat1900 uptime is 0day(s) 01hour(s) 34minute(s) 47second(s)cisco Catalyst 1900 (486sxl) processor with 2048K/1024K bytes of memoryHardware board revision is 1Upgrade Status: No upgrade currently in progress.Config File Status: No configuration upload/download is in progress27 Fixed Ethernet/IEEE 802.3 interface(s)Base Ethernet Address: 00-10-F6-21-F6-80
show version will show up on the exam for sure - router or switch.

What Catalyst command do you use to back up the running configuration to a TFTP server?
Use the copy nvram tftp://host/dst_file command to back up the running configuration to a TFTP server:

Cat1900#copy nvram tftp://192.168.0.3/cat1900.cfg

Configuration upload is successfully completed

Cat1900#

How do you restore a configuration file from a TFTP server on a Catalyst 1900 switch?
To restore a configuration file from a TFTP server, use the copy tftp://host/src_file nvram command:

Cat1900#copy tftp://192.168.0.3/cat1900.cfg nvram

TFTP successfully downloaded configuration file

Cat1900#

What Catalyst 1900 command would you use to restore the switch to its factory settings?
To restore a 1900 series switch to its factory settings, use the delete nvram command.

Note: For some reason I think this one was on my exam.

QUICK NOTES HOME

Quick Notes - ROUTING

2007-07-01T05:09:00.000-07:00

How do OSPF-enabled routers build adjacencies and exchange their routing tables?
OSPF-enabled routers build adjacencies by sending Hello packets out through all OSPF-enabled interfaces.

If these routers share a command link and agree on parameters set within their Hello packets then they become neighbors. If these parameters differ then the routers do not become neighbors and communication stops.

OSPF routers form adjacencies with certain routers. These routers are determined by the layer 2 (data link) media type and as soon as the adjacencies are formed each router sends LSAs (Link State Advertisements) to all adjacent routers. The LSAs describe the state of each router's links. There are multiple LSA types and a route that receives an LSA from a neighbor records the LSA in a link-state database and floods a copy of the LSA to all its other neighbors.

When all databases are complete - then each router uses the SPF (Shortest-Path First) algorithm to calculate a loop-free topology and builds its routing table based on this topology.
It is important to note that the Hello protocol is bidrectional and is the means by which neighbors are discovered and acts as keepalives between neighboring routers. It also establishes and maintain neighbor relationships and elects the DR (Designated Router) and BDR (Backup Designated Router) to represent the segment on Broadcast and NBMA (nobroadcast multiaccess) networks.

Note: Hello protocols are sent periodically sent out each OSPF-enabled interface using IP multicast address 224.0.0.5. The default interval on NBMA (nonbroadcast multiaccess) networks is 30 seconds. The default interval on Broadcast, Point-to-point, and point-to-multipoint networks is 10 seconds.

What are LSAs (link-state advertisements)?
LSAs are sent out all OSPF-enabled router interfaces describing the state of the router's links. They are also packets that OSPF uses to advertise changes in the condition of a link or other OSPF routers.

Name two LSA (link-state advertisement) types?
Type 1 LSAs are router LSAs and are generated by each router for the area to which the router belongs. These LSAs describe the states of the router'links to the area (area 0 for example) and are flooded within a single area (area 0 for example).

Type 2 LSAs are network LSAs and are generated by the DR (Designated Router) and the BDR (Backup Designated Router). They describe the routers attached to a particular network and are flooded within a single area (area 0 for example).

What is the routing metric OSPF is based on?
Bandwith.
Formula: Cost = 100,000,000 / bandwidth in bits per seconds
The cost of a 100 MBbps connection would be:
1000,000,000 / 100,000,000 =1

Based on the schema above -- if adjacencies are established with only with the DR (Designated Router) and BDR (Backup Designated Router)- what is the circuit count?
Formula:
2(n - 1) where n is the number of routers in the network.

2(5 - 1) = 8 circuits.
A circuit can also be thought of as an adjacency or connection.
Count four going into the DR and 4 going into the BDR for a total of 8.

Note: OSPF avoids synchronizing between every pair of routers in the network by using a DR and BDR. This way adjacencies are formed only to the DR and BDR, and the number of LSAs sent over the network is reduced. Now only the DR and BDR have four adjacencies, and all the other routers have two.

On an OSPF-enabled router -- what is the router ID and where does an OSPF-enabled router receive its router ID?
To initialize - OSPF must be able to define a router ID. The most common and stable source for a router ID is the IP address set on the logical loopback interface that is always available. If no logical interface is defined -- then the router receives its ID from the highest IP address on the physical interfaces.

Note: If two loopback addresses are defined -- it will use the highest loopback address. Think highest logical or highest physical interface address.

Name five OSPF network types:
Broadcast networks: Ethernet/Token Ring. OSPF-enabled routers on broadcast networks elect a DR (Designated Router) and BDR (Backup Designated Router). All the routers in the network form adjacencies with the DR and BDR. Note: OSPF packets are multicast to the DR and BDR.

NBMA (nonbroadcast multiaccess) networks: Frame Relay/X.25/ATM. NBMA networks can connect more than two routers but have no broadcast functionality. These networks elect an DR and BDR. Note: OSPF packets are unicast.

Point-to-point networks: A physical DS1 (T1) for example.

Point-to-point networks connect a pair of routers and always becomes adjacent.

Point-to-multipoint networks: Point-to-multipoint networks are a special configuration of NBMA networks in which networks are treated as a collection of point-to-point links. Point-to-multipoint networks do not elect a DR or BDR. Note: OSPF packets are multicast.

Virtual links: Virtual links area special configuration that the router interprets as unnumbered point-to-point networks. The network administrator creates/defines virtual links.

What is routing?
Routing is the process in which items are forwarded from one location to another. Routing is a hop-by-hop paradigm.
A Cisco router performs routing and switching functions. Describe what each function does.
Routing is a way to learn and maintain awareness of the network topology. Each router maintains a routing table in which it looks up the destination Layer 3 address to get the packet one step closer to its destination.The switching function is the actual movement of temporary traffic through the router, from an inbound interface to an outbound interface.

What are the three types of routes you can use in a Cisco router?
The three types of routes are static routes, dynamic routes, and default routes.

What is the difference between static and dynamic routes?
Static routes are routes that an administrator manually enters into a router. Dynamic routes are routes that a router learns automatically through a routing protocol.

How do you configure a static route on a Cisco router?
To configure a static route on a Cisco router, enter the ip route destination-network [mask] {next-hop-address outbound-interface} [distance] [permanent] global command. Here's an example:
RouterB(config)#ip route 172.17.0.0 255.255.0.0 172.16.0.1

This example instructs the router to route to 172.16.0.1 any packets that have a destination of 172.17.0.0 to 172.17.255.255

What is a default route?
Also known as the gateway of last resort, a default route is a special type of static route with an all-zeros network and network mask. The default route is used to route any packets to a network that a router does not directly know about to a next-hop router. By default, if a router receives a packet to a destination network that is not in its routing table, it drops the packet. When a default route is specified, the router does not drop the packet. Instead, it forwards the packet to the IP address specified in the default route.

How do you configure the default route on a Cisco router?
To configure a default route on a Cisco router, enter the following global configuration command:
ip route 0.0.0.0 0.0.0.0 [ip-address of the next-hop router outbound-interface]
For example:
RouterB(config)#ip route 0.0.0.0 0.0.0.0 172.16.0.2

What is a routing protocol?
A routing protocol defines the set of rules used by a router when it communicates with neighboring routers. Routing protocols listens for packets from other participants in order to learn and maintain a routing table.

What are the two major types of routing protocols?
The two major types of routing protocols are
· Interior Gateway Protocol (IGP)

· Exterior Gateway Protocol (EGP)

IGP is used to exchange routing information among routers in the same autonomous system (AS). EGP is used to communicate between ASs.

Note: For more information about autonomous systems, see Interconnecting Cisco Network Device (Cisco Press).

What is administrative distance?
Administrative distance (AD) is an integer from 0 to 255 that rates the trustworthiness of routing information received on a router from a neighboring router. The AD is used as the tiebreaker when a router has multiple paths from different routing protocols to the same destination. The path with the lower AD is the one given priority.

What are the three classes of routing protocols?
The three classes of routing protocols are
· Distance vector· Link-state· Balanced hybrid

What is the AD for each of the following?
· Directly connected interface

· Static route

· EIGRP

· IGRP

· OSPF

· RIP

· External EIGRP

· Unknown

The ADs are as follows:
Directly connected interface 0

Static route 1
EIGRP 90
IGRP 100
OSPF 110
RIP 120
External EIGRP 170
Unknown 255

How do distance vector routing protocols function?
Also known as Bellman-Ford-Fulkerson algorithms, distance vector routing protocols pass complete routing tables to neighboring routers. Neighboring routers then combine the received routing table with their own routing table. Each router receives a routing table from its directly connected neighbor. Distance vector routing tables include information about the total cost and the logical address of the first router on the path to each network they know about.

How do distance vector routing protocols keep track of any changes to the internetwork?
Distance vector routing protocols keep track of an internetwork by periodically broadcasting updates out all active interfaces. This broadcast contains the entire routing table. This method is often called routing by rumor.
Slow convergence of distance vector routing protocols can cause inconsistent routing tables and routing loops.

What are some mechanisms that distance vector protocols implement to prevent routing loops and inconsistent routing tables?
Here are some of the ways distance vector routing protocols prevent routing loops and inconsistent routing tables:
· Maximum hop count· Split horizon

· Route poisoning· Holddowns

What is maximum hop count?
If a loop is in an internetwork, a packet loops around the internetwork forever. Maximum hop counts prevent routing loops by defining the maximum number of times a packet will loop around the internetwork. RIP uses a hop count of up to 15, so anything that requires 16 hops is unreachable. Anytime a packet passes through a router, it is considered one hop.

What is split horizon?
The rule of split horizon is that it is never useful to send information about a route back in the direction from which the original update came.

What is convergence?
Convergence is when all routers have consistent knowledge and correct routing tables.

What is route poisoning?
With route poisoning, when a distance vector routing protocol notices that a route is no longer valid, the route is advertised with an infinite metric, signifying that the route is bad. In RIP, a metric of 16 is used to signify infinity. Route poisoning is used with holddowns.

What are hold-down timers?
Hold-down timers prevent regular update messages from reinstating a route that might have gone bad. Hold-down timers also tell routers to hold for a period of time any changes that might affect routes.

What are triggered updates?
When a router notices that a directly connected subnet has changed state, it immediately sends another routing update out its other interfaces rather than waiting for the routing update timer to expire. Triggered updates are also known as Flash updates.

What is IP RIP?
IP RIP is a true distance vector routing protocol that sends its complete routing table out all active interfaces every 30 seconds. IP RIP uses a hop count as its metric to determine the best path to a remote network. The maximum allowable hop count is 15, meaning that 16 is unreachable. There are two versions of RIP. Version 1 is classful, and version 2 is classless. IP RIP can load-balance over as many as six equal-cost paths.

What four timers does IP RIP use to regulate its performance?
Here are the four timers that IP RIP uses to regulate its performance: · Route update timer Time between router updates. The default is 30 seconds.· Route invalid timer Time that must expire before a route becomes invalid. The default is 180 seconds.· Route hold-down timer If IP RIP receives an update with a hop count higher than the metric recorded in the routing table, the router goes into holddown for 180 seconds.· Route flush timer Time from when a route becomes invalid to when it is removed from the routing table. The default is 240 seconds.

How do you enable RIP on a Cisco router?
To enable RIP on a Cisco router, start by using the router global configuration command, followed by the rip protocol. This selects RIP as the routing protocol. Then you assign the network command, followed by the directly connected network number(s) you want to activate RIP on. Here's an example:
RouterB(config)#router rip

RouterB(config-router)#network 192.168.1.0

RouterB(config-router)#network 192.168.2.0

How do you stop RIP updates from propagating out an interface on a router?
Sometimes you do not want RIP updates to propagate across the WAN, wasting valuable bandwidth or giving out valuable information about your internetwork. The easiest way to stop RIP updates from propagating out an interface is to use the passive-interface global configuration command.

How do you display the contents of a Cisco IP routing table?
The show ip route command displays the Cisco routing table's contents.

What is Interior Gateway Routing Protocol (IGRP)?
IGRP is a Cisco proprietary distance vector routing protocol. IGRP has a default hop count of 100 hops, with a maximum hop count of 255. IGRP uses bandwidth and line delay as its default metric, but it can also use reliability, load, and MTU.

How do you enable IGRP on a Cisco router?
The way you enable IGRP on a Cisco router is similar to the way you enable RIP, except you specify IGRP as the protocol and add an autonomous system number. For example:
RouterA(config)#router igrp 10 (10 is the AS number)

RouterA(config-router)#network 192.168.0.0

RouterA(config-router)#network 192.168.1.0

RouterA(config-router)#network 192.168.2.0

What four timers does IGRP use to regulate its performance?
The four timers IGRP uses to regulate its performance are as follows:

· Route update timer Time between router updates The default is 90 seconds.

· Route invalid timer Time that must expire before a route becomes invalid . The default is 270 seconds.

· Route hold-down timer If a destination becomes unreachable, or if the next-hop router increases the metric recording in the routing table, the router goes into holddown for 280 seconds.

· Route flush timer[md]Time from when a route becomes invalid to when it is removed from the routing table. The default is 630 seconds.

QUICK NOTES HOME

Quick Notes - PPP

2007-07-01T05:04:00.000-07:00

PPP can be used over what physical WAN interfaces?
PPP can be used on the following:
Asynchronous serial interfaces
High-Speed Serial Interface (HSSI)
ISDN
Synchronous serial interfaces

PPP is a data link layer protocol that provides network-layer services. What are the two sublayers of PPP?
The two sublayers of PPP are the following:

Network Core Protocol (NCP) is the component that encapsulates and configures multiple network layer protocols. Some examples<>

Link Control Protocol (LCP) is used to establish, configure, maintain, and terminate PPP connections.

What features does LCP offer to PPP encapsulation?
LCP offers authentication, callback, compression, error detection, and multilink to PPP encapsulation.

The two methods of authentication on PPP links are:
Password Authentication Protocol (PAP)
Challenge Handshake Authentication Protocol (CHAP)

PAP is the less-secure of the two methods; passwords are sent in clear text and are exchanged only upon initial link establishment.

CHAP is used upon initial link establishment and periodically to make sure that the router is still communicating with the same host. CHAP passwords are exchanged as MD5 encrypted values.

What two protocols are available for compression on PPP links?
The two protocols available for compression are Stacker and Predictor.

What three phases are used to establish a PPP session?
The three phases used to establish a PPP session are the following:
Step 1. Link establishment--Each PPP device sends LCP packets to configure and test the link (Layer 1).

Step 2. Authentication phase (optional)--If authentication is configured, either PAP or CHAP is used to authenticate the link. Authentication must take place before the network layer protocol phase can begin (Layer 2).

Step 3. Network layer protocol phase--PPP sends NCP packets to choose and configure one or more network layer protocols to be encapsulated and sent over the PPP data link (Layer 3).

Note on authentication: Hostname and passwords are case-sensitive.

How do you enable PPP encapsulation on a Cisco router serial interface?
To enable PPP encapsulation on a serial interface, enter the encapsulation ppp interface command:
RouterB(config-if)#encapsulation ppp

How do you enable PPP authentication using PAP or CHAP on a Cisco router?
To enable PPP authentication on a Cisco router, follow these steps:

Step 1. Make sure that each router has a host name assigned to it using the hostname command.

Step 2. On each router, define the username of the remote router and password that both routers will use with the username name password password command.

Step 3. Configure PPP authentication with the ppp authentication {chap chap pap pap chap pap} interface command. (If both PAP and CHAP are enabled, the first method you specify in the command is used. If the peer suggests the second method or refuses the first method, the second method is used.)

For example:

RouterB(config)#hostname RouterB

RouterB(config)#username RouterA password cisco

RouterB(config)#int s0

RouterB(config-if)#ppp authentication chap pap

What is the default encapsulation on a Cisco serial interface?

HDLC

QUICK NOTES HOME

Quick Notes - Network Management

2007-07-01T04:35:00.000-07:00

What is the Cisco Discovery Protocol (CDP)?
CDP is a Cisco proprietary protocol that runs on all Cisco IOS-enabled devices. It is used to gather information about directly connected neighboring devices. CDP operates at Layer 2 of the OSI model and is media-independent. With CDP, you can tell the hardware type, device identifier, address list, software version, and active interfaces on neighboring Cisco devices. CDP is enabled by default on all Cisco equipment. It uses a nonroutable SNAP frame to communicate between devices.

Note: Because CDP is media-independent it can operate over most media types. The only media types CDP cannot operate over are X.25, because it doesn't support SNAP encapsulation, and Frame Relay point-to-multipoint interfaces.

What are three reasons to disable CDP?
Three reasons to disable CDP are as follows:
. To save network bandwidth by not exchanging CDP frames.
. If you are connecting to non-Cisco devices.
. Security. CDP broadcasts information about the device every 60 seconds. Sniffers and other devices can view these broadcasts to discover information about your network.

How do you disable CDP on Cisco routers?
Two commands disable CDP on a Cisco router. To disable CDP on the entire device, use the no cdp run global command:

RouterB(config)#no cdp run
To disable CDP on an interface only, use the no cdp enable interface command:

RouterB(config)#int e0

RouterB(config-if)#no cdp enable
This disables CDP on Ethernet interface 0.

What does the show CDP command display?
The show CDP command displays global CDP information about the device. It tells you when the device will send CDP packets and the CDP holdtime:

RouterB#show cdp

Global CDP information:

Sending CDP packets every 60 seconds

Sending a holdtime value of 180 seconds

Note: For the CCNA test, remember that the default time a device will send out CDP information is 60 seconds and the default holdtime is 180 seconds.

On a Cisco router, what does the show cdp neighbors command display?
The show cdp neighbors command displays the following:

· Device ID (name of the device)

· The local interface (local outgoing port)

· The holdtime displayed in seconds

· The device's capability code (this tells you if the device is a router, switch, or repeater)

· Hardware platform of the neighboring device (what type of Cisco device it is and the model)

· Port ID of the neighboring device (remote port)

RouterB#show cdp neighbors

Capability Codes:

R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater

Device ID Local Intrfce Holdtme Capability Platform Port ID

RouterA Ser 0 146 R 2505 Ser 0

What does the show cdp neighbors detail command display?
The show cdp neighbors detail and show cdp entry * commands show the same output. They both display the following:

· Device ID (host name) of the remote neighbor

· Layer 3 address of the remote device (if the device has more than one Layer 3 address on its interface, only the primary address is shown)

· Device platform and capabilities· Local interface and outgoing port ID

· Remote device holdtime in seconds

· IOS type and version

RouterB#show cdp neighbors detail

-------------------------

Device ID: RouterA

Entry address(es):

IP address: 192.168.2.1

Platform: cisco 2505, Capabilities: Router

Interface: Serial1, Port ID (outgoing port): Serial1

Holdtime : 164 sec Version :Cisco Internetwork Operating System Software

IOS (tm) 2500 Software (C2500-D-L), Version 12.0(13), RELEASE SOFTWARE

(fc1)Copyright (c) 1986-2000 by cisco Systems, Inc.Compiled Wed 06-Sep-00 01:08 by Linda

What does the show cdp traffic command display?
The show cdp traffic command displays information about interface traffic. This includes the number of CDP packets sent and received and CDP errors:

RouterB#show cdp traffic

CDP counters :

Packets output: 105, Input: 103

Hdr syntax: 0, Chksum error: 0, Encaps failed:

No memory: 0, Invalid packet: 0, Fragmented: 0

What does the show cdp interface command display?
The show cdp interface command displays the status of CDP on all interfaces on your device: RouterB#show cdp interface

Ethernet0 is up, line protocol is down

Encapsulation ARPA

Sending CDP packets every 60 seconds Holdtime is 180 seconds

Serial0 is up, line protocol is up

Encapsulation HDLC

Sending CDP packets every 60 seconds Holdtime is 180 seconds

Serial1 is up, line protocol is up

Encapsulation HDLC

Sending CDP packets every 60 seconds Holdtime is 180 seconds

What Cisco IOS router command can you use to see a neighbor router's IP address?
To see a neighbor router's IP address, you must use the show cdp neighbor detail or show cdp entry * user mode or EXEC command. (This one will probably be on the exam)

What IOS command do you use to view the active outbound telnet sessions for the current user on a Cisco router?
The show sessions command displays the active outbound telnet sessions from that particular user on your router.

RouterA#show sessions

Conn Host Address Byte Idle Conn Name

* 1 192.168.1.2 192.168.1.2 0 0 192.168.1.2

What key sequence do you use to suspend a Telnet session on a remote system and return to your local router?
To suspend a Telnet session, press Ctrl-Shift-6, and then press X.

How do you end a remote Telnet session on a Cisco router?
To end a Telnet session, use the exit or logout command while you're on the remote device: RouterB>exit

[Connection to 192.168.1.2 closed by foreign host]

RouterA#

Upon using the ping EXEC command, you receive one of the following responses:

· .

· !

· ?

· C

· U

· I
What does each of these responses mean?

. = Each period indicates that the network server timed out while waiting for a reply.

! =Each exclamation point indicates the receipt of a reply.

? =Unknown packet type.

C =A congestion experienced packet was received.

U =A destination unreachable error PDU was received.

I = The user interrupted the test.

What is the trace EXEC command used for?

RouterA#trace 192.168.2.2

Type escape sequence to abort.

Tracing the route to 192.168.2.2

1 192.168.2.2 16 msec 16 msec *
Note: If trace responds with a * it means the probe timed out. If it responds with a ? it means it received an unknown packet type.

What are the two ways in which a Cisco router resolves host names to IP addresses?
A Cisco router resolves host names using either a host table on each router or a DNS server.

What is the main purpose of RAM on a Cisco router?
On most Cisco routers, the IOS is loaded into RAM, as well as the running configuration. It is also used to hold routing tables and packet buffers.

What is the function of ROM on a Cisco router?
On a Cisco router, ROM is used to start and maintain the router.

What is Flash memory used for on a Cisco router?
Flash memory is used to store the Cisco IOS software image and, if there is room, multiple configuration files or multiple IOS files. On some routers (the 2500 series), it is also used to run the IOS.

What is the function of NVRAM on a Cisco router?
Nonvolatile Random-Access Memory (NVRAM) is used to hold the saved router configuration. This configuration is not lost when the router is turned off or reloaded.

What is the main purpose of the configuration register on a Cisco router?
The configuration register's main purpose is to control how the router boots up. It is a 16-bit software register that by default is set to load the Cisco IOS from Flash memory and to look for and load the startup-config file from NVRAM.

What Cisco IOS command would you use to view the current configuration register value?
The show version command is used to display the router's current configuration register: RouterA#show version

Cisco Internetwork Operating System SoftwareIOS (tm) 2500 Software (C2500-D-L),

Version 12.0(13), RELEASE SOFTWARE (fc1)Copyright (c) 1986-2000 by cisco Systems, Inc.Compiled Wed 06-Sep-00 01:08 by lindaImage text-base: 0x030388F8, data-base: 0x00001000 Configuration register is 0x2102

How do you change the configuration register on a Cisco router?
To change the configuration register on a Cisco router, use the config-register global command.

What Cisco IOS command displays the contents of Flash memory?
The show flash command displays the contents of Flash memory. This includes the images stored in Flash memory, the images' names, bytes used in Flash memory, bytes available, and the total amount of Flash memory on your router:

RouterA#show flash

System flash directory:File Length Name/status

1 6897716 c2500-d-l.120-13.bin[6897780 bytes used, 1490828 available, 8388608 total]8192K bytes of processor board System flash (Read ONLY)

What IOS command would you use to copy the running configuration on a router to a TFTP server?
To copy the running configuration to a TFTP server, use the copy running-config tftp privileged EXEC command:

RouterB#copy run tftp

Address or name of remote host []? 192.168.0.2

Destination filename [routerb-confg]?

!!

780 bytes copied in 6.900 secs (130 bytes/sec)
This gives you a backup of your running config on a TFTP server.

How do you erase the router's configuration and bring it back to the factory default?
The erase startup-config privileged EXEC command erases your router's configuration, thus bringing it back to its factory defaults:

RouterB#erase startup-config

Erasing the nvram filesystem will remove all files! Continue? [confirm]

[OK]Erase of nvram: complete
Note: In order to complete the process, you need to reload the router. An older IOS command that you can use to accomplish the same results is write erase.

How do you restore a configuration file from a TFTP server into your Cisco router's RAM?
The copy tftp running-config privileged EXEC command merges the saved and running configuration into your router's RAM, so any commands not explicitly change or removed will remain in the running configuration.
RouterB#copy tftp running-config

Address or name of remote host []? 192.168.0.2

Source filename []? routerb-confg

Destination filename [running-config]?

Accessing tftp://192.168.0.2/routerb-confg...

Loading routerb-confg from 192.168.0.2 (via Ethernet0):

!

[OK - 780/1024 bytes] 780 bytes copied in 4.12 secs (195 bytes/sec)

RouterB# 01:40:46: %SYS-5-CONFIG: Configured from tftp://192.168.0.2/routerb-confg

How do you back up a Cisco router IOS?
To back up the current IOS image on your router, use the copy flash tftp privileged EXEC mode command:

RouterB#copy flash tftp

Source filename [routerb-flash]? flash:c2500-d-l.120-13.bin

Address or name of remote host []? 192.168.0.2

Destination filename [c2500-d-l.120-13.bin]?

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!6897716 bytes copied in 90.856 secs (76641 bytes/sec)

How do you upgrade or restore the Cisco router IOS?
To upgrade or restore the Cisco router IOS, use the copy tftp flash privileged EXEC mode command.

How you make a Cisco router a TFTP server?
To configure a Cisco router as a TFTP server, use the tftp-server global configuration command.

What is the boot sequence of a Cisco router?
The boot sequence of a router is as follows:
hardware /power on

load run bootstrapfind the IOS software

load the softwarefind the config (default NVRAM)

load the configuration (startup-config) into RAM

Run the IOS

What can you configure on a router in setup mode?
ip addresses

routed protocols

enable password

Important Config Register Notes:
2100 manual boot rommon>

2101 boot from ROM

2102 normal/password recovery

2105 boot system command - config-register NVRAM

2142 bypass NVRAM

ctrl-break = ROM monitor mode

router(config)#boot system flash ios filename

router(config)#boot system tftp filename ip address

router(config)#boot system ROM

Note the router prompt for boot commands. Copy commands = router#

QUICK NOTES HOME

Quick Notes - ISDN

2007-07-01T04:22:00.000-07:00

In ISDN, what do E-series protocols specify?
E-series protocols specify telephone network standards for ISDN. Examples include International ISDN addressing and the International Telephone plan.

What do protocols that begin with I deal with?
I-series protocols deal with concepts, terminology, and general methods of ISDN, such as service aspects, user network interfaces, and network aspects.

What do ISDN protocols that begin with Q specify?
Q-series protocols specify how switching and signaling (call setup) should operate. For example, ISDN protocol Q.921 is used for LAPD on the D channel, and protocol Q.931 is used for the ISDN network layer between the terminal and switch.

What is the data transfer speed for ISDN BRI?
The data transfer rate for ISDN BRI is 128 Kbps. The total transfer rate for ISDN BRI is 144 Kbps. This consists of two 64 Kbps (128 Kbps) Bearer (B) channels plus one 16 Kbps Delta (D) channel. The B channels can be used for data transfer and voice transmission. The D channel carries control and signaling information for fast call setup and operates at the first three layers of the OSI model.

What is the total rate in Mbps for ISDN PRI?
The total rate for ISDN PRI in the U.S. and Japan is 1.544 Mbps. PRI consists of 23 64 Kbps B channels and one 64 Kbps D channel. In Europe, PRI consists of 30 B channels and one D channel for a total rate of 2.048 Mbps.
In ISDN, the D channel appears to always be up and is what makes the call to the ISDN switch.

What signaling protocol does the ISDN switch use to set up a path and pass the called number to the terminating ISDN switch?
The ISDN local switch uses the SS7 protocol to set up a path and pass the called number to the terminating ISDN switch.

Devices connecting to an ISDN network are known as terminal equipment (TE) and network termination (NT) equipment. What do the TE1 and TE2 equipment types refer to?
TE1 refers to a device that has a native ISDN interface. That is, it can plug directly into an ISDN network. TE2 refers to equipment that does not have an ISDN interface and that requires a terminal adapter (TA) to plug into an ISDN network.

To what do ISDN NT1 and NT2 termination types refer?
Network Terminal 1 converts BRI signals into a form used by the ISDN line. It implements the physical layer specifications and connects the devices to the ISDN network. NT2 is the point where all ISDN lines are aggregated and switched using a customer-switching device.

What is the function of the TA?
The terminal adapter converts non-ISDN signals into ISDN signals. Devices that are not native to ISDN connect to a TA to access the ISDN network.

What does the ISDN R reference point define?
The R reference point defines the point between a non-ISDN-compatible device and a TA.

What does the ISDN S point reference?
The S point references the points or customer equipment that connects to the NT2 or customer-switching device.

What does the ISDN T reference point define?
ISDN T reference points refer to the point between NT1 and NT2 devices. T and S reference points are electronically the same and reference the outbound connection from the NT2 to the ISDN network.

What is the ISDN U reference point?
The U reference point is the point between the NT1 and the ISDN network.

What happens when you connect a router with a U interface into an NT1?
If you connect a router with a U interface into an NT1, you will damage the interface. This is because the U interface on a Cisco router already has a built-in NT1.

What are SPIDs?
Service provider or profile identifiers (SPIDs) are used to identify your router to the switch at the central office (the ISP). They are a series of characters that look like phone numbers and are not always required.

How do you enable ISDN on a Cisco router?
To enable ISDN on a Cisco router, first you need to define the switch type your router will be connecting to. The switch type is the type of switch used by your service provider. To define the ISDN switch type, enter the isdn switch-type switch-type global or interface command. Specifying the isdn switch-type global command specifies the ISDN switch type for the entire router. The second step is to enter the SPIDs provided by your service provider by entering the isdn spid1 spid-number and isdn spid2 spid-number interface commands. The following example enables ISDN on a router, specifying AT&T basic-rate switches as the switch type:

RouterA(config-if)#isdn switch-type basic-5ess

RouterA(config-if)#isdn spid1 123456789123

RouterA(config-if)#isdn spid2 123456789124

If you have DDR enabled on your router, when does the router decide when to bring up the ISDN line and send traffic?
If DDR is enabled on your router, it brings up the ISDN line when it sees "interesting traffic".

How do you enable DDR on a Cisco router?
To enable DDR on a Cisco router, you first need to define static routes with the ip route command. Next, specify interesting traffic, and finally, configure the dialer information.

How do you specify interesting traffic?
As an administrator, you define that interesting traffic can be based on protocol type or addresses for source or destination hosts. To define interesting traffic, use the following command: dialer-list dialer-group protocol protocol-name {permit deny list access-list-number}
dialer-group is the number that identifies the dialer list. protocol-name can be IP, IPX, AppleTalk, DECnet, or Vines.

RouterA(config)#dialer-list 10 protocol ip list 100

RouterA(config)#access-list 100 permit tcy any any eq www

RouterA(config)#access-list 100 permit tcy any any eq smtp

RouterA(config)#access-list 100 permit tcy any any eq dns

The last step in configuring DDR on a Cisco router is to configure the dialer information. How do you do this?
Do the following to configure the dialer information:
Step 1. Choose the interface.
Step 2. Configure an IP address on the interface.
Step 3. Configure the encapsulation type.
Step 4. Bind interesting traffic to the interface by using the dialer-group group-number interface command.

What command can you use to view the call in progress?
The show isdn active command shows the call in progress and the number dialed:

show isdn st

RouterA#Global ISDN Switchtype = basic-5ess

ISDN BRI0 interface dsl 0, interface ISDN Switchtype = basic-5ess

Layer 1 Status:

ACTIVE

Layer 2 Status: TEI = 64, Ces = 1, SAPI = 0, State =

MULTIPLE_FRAME_ESTABLISHED

Layer 3 Status: 0 Active Layer 3 Call(s) Activated dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0

How can you view the number of times the dial string has been successfully reached on a Cisco router?

The show dialer command displays information about the interface configured for DDR, the number of times the dialer string has been successfully reached, and the fast and idle timer values for each B channel.

QUICK NOTES HOME

Quick Notes - IOS COMMANDS

2007-07-01T03:59:00.000-07:00

What two EXEC modes are supported in the Cisco IOS?
The two EXEC modes are:
User EXEC mode (user mode)
Privileged EXEC mode (enable or privileged mode)

In the IOS, what is User EXEC mode?
User EXEC mode is the first mode you enter when you log into the IOS. This mode is limited and is mostly used to view statistics. You cannot change a router's configuration in this mode. By default, the greater-than sign (>) indicates that you are in user mode. This is how the router prompt looks in user mode: Router>

In the IOS, what is privileged EXEC mode?
In privileged EXEC mode, you can view and change the configuration in a router. To enter privileged mode, enter the enable command while in user mode. The pound symbol (#) indicates that you are in privileged mode. This mode is usually protected with a password. You also see the output of the prompt:

Router>enable
Password:
Router#

When you are in privileged EXEC mode, how do you return to user EXEC mode?
You return to user EXEC mode using the disable, exit, or end IOS commands. Here is an example of using the disable command:

Router#disable
Router>

What two types of content-sensitive help are available in the Cisco IOS?
Word help and command syntax help are the two types of content-sensitive help. Word help uses a question mark and identifies commands that start with a character or sequence of characters. For example, the following router output shows the use of word help for any IOS command that starts with the letters cl:

Router#cl?
clear clock
Command syntax help is when you use a question mark after a command so that you can see how to complete the command.

For example:
Router#clock ?
set Set the time and date

On a Cisco router, what does the show version command display?
The show version command displays the system hardware's configuration, including RAM, Flash memory, software version, configuration register, and boot images. Here is an example of the show version command:

Router#show version
Cisco Internetwork Operating System SoftwareIOS (tm) 2500 Software (C2500-D-L), Version 12.0(13), RELEASE SOFTWARE (fc1)Copyright (c) 1986-2000 by Cisco Systems, Inc.Compiled Wed 06-Sep-00 01:08 by lindaImage text-base: 0x030388F8, data-base: 0x00001000 ROM: System Bootstrap, Version 5.2(5), RELEASE SOFTWAREBOOTFLASH: 3000 Bootstrap Software (IGS-RXBOOT), Version 10.2(5), RELEASE SOFTWARE (fc1) Router uptime is 50 minutesSystem restarted by power-onSystem image file is "flash:c2500-d-l.120-13.bin" cisco 2505 (68030) processor (revision C) with 8192K/2048K bytes of memory.Processor board ID 02073409, with hardware revision 00000000(text omitted)32K bytes of non-volatile configuration memory.8192K bytes of processor board System flash (Read ONLY) Configuration register is 0x2102

On a Cisco router, how do you display the configuration running in RAM?
You display the configuration running in RAM using the show running-config privileged mode command. For example:

Router#show running-config
Building configuration...
Current configuration:
!
version 12.0service timestamps debug uptimeservice timestamps log uptimeno service password-encryption
!
hostname Router
!
enable password cisco
!
--More--

On a Cisco router, how do you view the configuration stored in NVRAM?
You view the configuration stored in NVRAM using the show startup-config privileged mode command.

What Cisco router command would you use to view a list of the most recently used commands?
The show history command, by default, displays the last ten commands used. You can also use the up arrow key (or Ctrl-P) to display the last command you entered and the down arrow key (or Ctrl-N) to display the previous commands you entered. The following is an example of the show history command:

Router#show history
en
show running-config
show running-config
show history
enable
show version
show time
show history
Router#

Command history is enabled by default and records ten commands in its history buffer for the current session. How do you edit the number of commands that are stored in the router's history buffer?
To edit the number of command lines stored for the current session, use the terminal history [size number-of-lines] command in privileged EXEC mode. For example, the following changes the history size to 20 lines:

Router#terminal history size 20
Note: The maximum number of lines you can set for the current session is 256, but doing so wastes router memory. To turn off terminal history, use the terminal no history privileged mode command. If you want to set the history size longer than the current session, go to the console interface and enter the history [size number-of-lines] interface command as a more permanent way of changing the history buffer. This command is unavailable on a Catalyst 1900 switch.

On a Cisco router, name the enhanced editing commands that are used to do the following: ·
Move the cursor to the beginning of the line
· Move the cursor to the end of the line
· Move the cursor forward one character
· Move the cursor back one character
· Move the cursor back one word· Delete a line
· Complete a line· Display a line versus a screen
Move the cursor to the beginning of the line Ctrl-A
Move the cursor to the end of the line Ctrl-E
Move the cursor forward one character Ctrl-F
Move the cursor back one character Ctrl-B
Move the cursor back one word Esc-B
Delete all characters from the cursor to the beginning of the command
line - Ctrl-U
Complete a line - Tab
Display a line versus a screen - Enter

What are global commands on a Cisco router?
Global configuration commands are commands that affect the entire router. They can be executed only in global configuration mode.

How do you enter global configuration mode?
To enter global configuration mode, you enter the config terminal command from privileged EXEC mode. Here is an example of this command:
Router#config terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#

How do you configure a name on a Cisco router?
The hostname name global configuration command is used to configure a name on a Cisco router. For example, the following command changes the router's host name to RouterA:

Router(config)#hostname RouterA
RouterA(config)#

How do you add a message-of-the-day (MOTD) banner on a Cisco router?
To add a message-of-the-day banner to a Cisco router, enter the banner motd # text # global configuration command. The pound signs (#) are delimiting characters. They can be any character of your choice, but they must be the same and cannot be included in your text. They signify the beginning and end of your text. The following example shows the banner motd command:

RouterA(config)#banner motd # Enter TEXT message. End with the character '#'.Warning only authorized users many access this Router. #

RouterA(config)#
Note: The MOTD banner is displayed to anyone connecting to the router via Telnet, console port, or auxiliary port.

On a Cisco router, how do you add a password to the console terminal?
To add a password to the console terminal, use the line console 0 global configuration command, followed by the login and password password line subcommands:

RouterA(config)#line console 0
RouterA(config-line)#login
RouterA(config-line)#password CCNA
In this example, the login subcommand forces the router to prompt for authentication. Without this command, the router will not authenticate a password. The password CCNA command sets the console password to CCNA. The password you set is case-sensitive.

How do you add a password for Telnet access on a Cisco router?
To add a password for Telnet access, enter the line vty 0 4 global configuration command, the login command, and finally the password line subcommand. The password is case-sensitive. In this example, the Telnet password is set to CCNA:

RouterA(config)#line vty 0 4
RouterA(config-line)#login
RouterA(config-line)#password CCNA

What command do you use to add a password to the auxiliary interface on your Cisco router?
To add a password to the auxiliary interface, use the line aux global configuration command, followed by the login and password subcommands. is the number of the auxiliary port you want to add a password to. The password is case-sensitive. The following example sets the password for the auxiliary port to CCNA:
RouterA(config)#line aux 0
RouterA(config-line)#login
RouterA(config-line)#password CCNA

On a Cisco router, how do you set a password to restrict access to privileged EXEC mode?
You set a password to restrict access to privileged EXEC mode using the enable password global configuration command:

RouterA(config)#enable password CCNA
This example sets the password to enter privileged mode to CCNA.

By default, when you view the router's configuration, the enable password is not encrypted. What command can you enter to use an encrypted enable password?
To use an encrypted enable password, use the enable secret password global configuration command, where password is a case-sensitive password you assign:

RouterA(config)#enable secret Cisco
If you have an enable password on your router, the IOS will allow you to use the same password as your enable password for your secret password, but this is not recommended. This is because the enable password is not encrypted and anyone can view it. If you have both an enable and secret password configured on your router, the router will use the secret password and not the enable password.

When you view the configuration on Cisco routers, only the enable secret password is encrypted.

How do you encrypt user mode and the enable password?
To encrypt user mode and the enable password, use the service password-encryption global command:

RouterA(config)#service password-encryption

How do you configure Cisco router interfaces?
To configure an interface on a Cisco router, use the interface interface-type number global command, where interface-type number is the interface type and number you want to configure. For example, if you want to configure the second serial interface on your router, you would enter the following:

RouterA(config)#interface serial 1
RouterA(config-if)#
Cisco interfaces start with 0 instead of 1. So the first interface would be number 0. The prompt also changes to RouterA(config-if)# to tell you that you are in interface mode. If you have a router with module slot, such as the Cisco 3600, you would enter into interface mode by entering the slot/port number. For example, if you have a Cisco 3600 router with two module serial interfaces and you want to configure the first serial interface on the second module you would enter interface s1/0.

How do you administratively disable an interface on a Cisco router?
You administratively disable an interface on a Cisco router by issuing the shutdown interface configuration command. In this example, the serial interface is issued the shutdown command: RouterA(config)#int s0
RouterA(config-if)#shutdown
00:27:14: %LINK-5-CHANGED: Interface Serial0, changed state to administratively down
To administratively enable an interface, use the no shutdown interface command.

What are some of the things the show interface interface-type number command displays?
The show interface command displays the following: · Whether the interface is administratively down· Whether the line protocol is up or down· An Internet address (if one is configured)· MTU and bandwidth· Traffic statistics on the interface· Interface encapsulation type

RouterA#show interface s0
Serial0 is down, line protocol is down
Hardware is HD64570 Internet address is 192.168.1.1/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation HDLC, loopback not set, keepalive set (10 sec) Last input never, output never, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/0/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 output buffer failures, 0 output buffers swapped out 0 carrier transitions DCD=up DSR=up DTR=down RTS=down CTS=up

On your Cisco router, you enter show interface s0 and notice that the port is administratively down. What does this mean, and how do you fix it?
When an interface is administratively down, it has been shut down manually. To remedy this, enter the interface command no shut.

What two commands can you use to show the clock rate on a serial interface?
To view the clock rate on a serial interface, you can use the show running-config enable command and the show controllers enable command.

Assuming that you are using no CSU/DSU and you are using back-to-back DTE/DCE serial cables, what command would you use to set the serial interface on a router to provide clocking to another router at 64 Kbps?
The command to set the serial interface on a router to provide clocking to another router at 64 Kbps is clock rate 64000. Setting the clock rate on an interface makes it a DCE interface.

What Cisco IOS router command would you use to find out whether a serial interface is a DCE or DTE interface (providing clocking)?
To see whether a serial interface is providing clocking, use the enable command show controllers serial-interface-type serial-number. The following example shows that serial interface 0 is providing clock rate at 56 Kbps:

RouterA#show controllers s 0
HD unit 0, idb = 0xCCE04, driver structure at 0xD2298buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 56000cpb = 0x81, eda = 0x4940, cda = 0x4800RX ring with 16 entries at 0x814800

QUICK NOTES HOME

Quick Notes - INTERNETWORKING

2007-07-01T02:15:00.000-07:00

What are the three layers of the Cisco Hierarchical Model?
The three layers of the Cisco Hierarchical Model are:1
The access layer
The distribution layer
The core layer

In the Cisco Hierarchical Model, what is the function of the access layer?
Sometimes referred to as the desktop layer, the access layer is the point at which users connect to the network through low-end switches. Some functions of the access layer include:
Connectivity into the distribution layer
Shared Bandwidth
MAC Address filtering (switching)
Segmentation

What is the function of the distribution layer in the Cisco Hierarchical Model?
The distribution layer is also known as the workgroup layer. It is the demarcation point between the access and core layers of the network. Its primary function is to provide routing, filtering, and WAN access. The distribution layer determines how packets access the core, so it is the layer at which to implement policy-based connectivity. Some functions include the following:
Collection point for access layer devices
Broadcast and multicast domain segmentation
Security and filtering services such as firewalls and access lists
Providing translation between different media types
Inter-VLAN routing

What is the role of the core layer in the Cisco Hierarchical Model?
The core layer is the backbone of the network. Its main function is to switch traffic as fast as possible. Therefore, it should not perform any filtering to slow down traffic.
The ISO's OSI Reference Model contains seven layers. What are they? Include the layer number and name of each layer in your answer.
The seven layers of the OSI model are as follows:
Layer 7 - Application layer

Layer 6 - Presentation layer

Layer 5 - Session layer

Layer 4 - Transport layer

Layer 3 - Network layer

Layer 2 - Data link layer

Layer 1 - Physical layer

What are some reasons that the industry uses a layered model?
Here are some reasons why the industry uses a layered model:
It encourages industry standardization by defining what functions occur at each level.
It allows vendors to modify or improve components at only one layer versus rewriting the whole protocol stack.
It helps interoperability by defining standards for the operations at each level.
It helps with troubleshooting.

What does the application layer (Layer 7) of the OSI model do, and what are some examples of this layer?
The application layer is the layer that is closest to the user. This means that this layer interacts directly with the software application. The application layer's main function is to identify and establish communication partners, determine resource availability, and synchronize communication. Some examples include the following:
TCP/IP applications such as Telnet, File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP), WWW, and HTTP.
OSI applications such as Virtual Terminal Protocol, File
Transfer, Access, and Management (FTAM), and Common Management Information Protocol (CMIP).

In the OSI model, what are the responsibilities of the presentation layer (Layer 6)? Give some examples of this layer.
Also known as the translator, the presentation layer provides coding and conversion functions to application layer data. This guarantees that the application layer on another system can read data transferred from the application layer of a different system. Some examples of the presentation layer are:
Compression, decompression, and encryption
JPEG, TIFF, GIFF, PICT, QuickTime, MPEG, and ASCII

What are the functions of the session layer (Layer 5)? Give some examples.
The session layer is responsible for creating, managing, and ending communication sessions between presentation layer entities. These sessions consist of service requests and responses that develop between applications located on different network devices. Some examples include SQL, RPC, NFS, X Window System, ZIP, NetBIOS names, and AppleTalk ASP.

What is the transport layer (Layer 4) responsible for? Give some examples of transport layer implementations.
The transport layer segments and reassembles data from upper-layer applications into data streams. It provides reliable data transmission to upper layers. End-to-end communications, flow control, multiplexing, error detection and correction, and virtual circuit management are typical transport layer functions. Some examples include TCP, UDP*, and SPX.
Note: watch out for end-to-end on communications on the exam! Transport layer.

* Error correction does not apply to UDP - connection-less - unreliable.....

What is flow control, and what are the three methods of implementing it?
Flow control is the method of controlling the rate at which a computer sends data, thus preventing network congestion. The three methods of implementing flow control are
Buffering
Congestion avoidance
Windowing
Almost certain to be on the exam.

Describe the function of the network layer (Layer 3), and give some examples of network layer implementations.
The network layer provides internetwork routing and logical network addresses. It defines how to transport traffic between devices that are not locally attached. The network layer also supports connection-oriented and connectionless service from higher-layer protocols. Routers operate at the network layer. IP, IPX, AppleTalk, and DDP are examples of network layer implementations.

Are network layer addresses physical or logical?
Network layer addresses are logical addresses specific to the network layer protocol being run on the network. Each network layer protocol has a different addressing scheme. They are usually hierarchical and define networks first and then host or devices on that network. An example of a network address is an IP address, which is a 32-bit address often expressed in decimal format. 192.168.0.1 is an example of an IP address in decimal format.

How do routers function at the network layer of the OSI model?
Routers learn, record, and maintain awareness of different networks. They decide the best path to these networks and maintain this information in a routing table. The routing table includes the following:
Network addresses, which are protocol-specific. If you are running more than one protocol, you have a network address for each protocol.
The interface the router uses to route a packet to a different network.
A metric, which is the distance to a remote network or the weight of the bandwidth, load, delay, and reliability of the path to the remote network.
Routers create broadcast domains. One interface on a router creates a single broadcast domain and collision domain. However, an interface on a switch creates only a single collision domain.

In addition to learning the remote network and providing a path to the network, what other functions do routers carry out?
Routers perform these tasks:
Routers, by default, do not forward broadcasts or multicasts.
Routers can perform bridging and routing functions.
If a router has multiple paths to a destination, it can determine the best path to the destination.
Routers forward traffic based on Layer 3 destination addresses.
Routers can connect Virtual LANs (VLANs).
Routers can provide quality of service for specified types of network traffic.

What is the responsibility of the data link layer (Layer 2)?
The data link layer provides functional and procedural means for connectionless mode among network entities, and for connection mode entities it provides the establishment, maintenance, and release of data link connections among network entities and for the transfer of data link service data units. The data link layer translates messages from the network layer into bits for the physical layer, and it enables the network layer to control the interconnection of data circuits within the physical layer. Its specifications define different network and protocol characteristics, including physical addressing, error notification, network topology, and sequencing of frames. Data link protocols provide the delivery across individual links and are concerned with the different media types, such as 802.2 and 802.3. The data link layer is responsible for putting 1s and 0s into a logical group. These 1s and 0s are then put on the physical wire. Some examples of data link layer implementations are IEEE 802.2/802.3, IEEE 802.5/802.2, packet trailer (for Ethernet, the FCS or CRC), FFDI, HDLC, and Frame Relay.

The IEEE defines what two sublayers of the data link layer?
The two sublayers of the data link layer are
The Logical Link Control (LLC) sublayer
The Media Access Control (MAC) sublayer
These two sublayers provide physical media independence.

For what is the LLC sublayer responsible?
The Logical Link Control (802.2) sublayer is responsible for identifying different network layer protocols and then encapsulating them to be transferred across the network. An LLC header tells the data link layer what to do with a packet after it is received.

What functions does the Media Access Control (MAC) sublayer provide?
The MAC sublayer specifies how data is placed and transported over the physical wire. The LLC layer communicates with the network layer, but the MAC layer communicates downward directly to the physical layer. Physical addressing (MAC addresses), network topologies, error notification, and delivery of frames are defined at this sublayer.

What are some network devices that operate at the data link layer?
Bridges and switches are network devices that operate at the data link layer. Both devices filter traffic by MAC addresses.

What is the function of the OSI model's physical layer (Layer 1)? Give some examples of physical layer implementations.
The physical layer defines the physical medium. It defines the media type, the connector type, and the signaling type (baseband versus broadband). This includes voltage levels, physical data rates, and maximum cable lengths. The physical layer is responsible for converting frames into electronic bits of data, which are then sent or received across the physical medium. Twisted pair, coaxial cable, and fiber-optic cable operate at this level. Other implementations at this layer are repeaters/hubs, RJ-45.

The Ethernet and IEEE 802.3 standards define what three physical wiring standards that operate at 10 Mbps?
These physical wiring standards operate at 10 Mbps:
10Base2
10Base5
10BaseT

What are collision domains?
In Ethernet segments, devices connect to the same physical medium. Because of this, all devices receive all signals sent across the wire. If two devices send a packet at the same time, a collision occurs. In the event of a collision, the two devices run a backoff algorithm and resend the packet. The devices retransmit up to 15 times. The first station to detect a collision issues a jam signal. When a jam signal is sent from a workstation, it affects all of the machines on the segment, not just the two that collided; when the jam signal is on the wire, no workstations can transmit data. The more collisions that occur in a network, the slower it will be, because the devices will have to resend the packet. A collision domain defines a group of devices connected to the same physical medium.

What are broadcast domains?
A broadcast domain defines a group of devices that receive each others' broadcast messages. As with collisions, the more broadcasts that occur on the network, the slower your network will be. This is because every device that receives a broadcast must process it to see if the broadcast is intended for it.

What devices are used to break up collision and broadcast domains?
Switches and bridges are used to break up collision domains. They create more collision domains and fewer collisions. Routers are used to break up broadcast domains. They create more broadcast domains and smaller broadcast areas.

How do the different layers of the OSI model communicate with each other?
Each layer of the OSI model can communicate only with the layer above it, below it, and parallel to it (a peer layer). For example, the presentation layer can communicate with only the application layer, session layer, and presentation layer on the machine it is communicating with. These layers communicate with each other using protocol data units (PDUs). These PDUs control information that is added to the user data at each layer of the model. This information resides in fields called headers (the front of the data field) and trailers (the end of the data field).
What is data encapsulation?
A PDU can include different information as it goes up or down the OSI model. It is given a different name according to the information it is carrying (the layer it is at). When the transport layer receives upper layer data, it adds a TCP header to the data; this is called a segment. The segment is then passed to the network layer, and an IP header is added; thus, the data becomes a packet. The packet is passed to the data link layer, thus becoming a frame. This frame is then converted into bits and is passed across the network medium. This is data encapsulation. For the CCNA test, you should know the following:
Application layer -- Data
Transport layer -- Segment
Network layer -- Packet
Data link layer -- Frame
There is also the Physical Layer -- Bits

What is the difference between a routing protocol and a routed protocol?
Routing protocols determine how to route traffic to the best location of a routed protocol. Examples of routing protocols are RIP, EIGRP, OSFP, and BGP. Examples of routed protocols are IP and IPX.

What 3 devices are used to segment a LAN?
Router
Switch
Bridge

QUICK NOTES HOME

Quick Notes - FRAME RELAY

2007-07-01T02:01:00.000-07:00

What protocol does Frame Relay rely on for error checking?
Frame Relay does not rely on any certain protocol for error checking. Instead, it relies on upper-layer protocols to provide error checking. For example, Frame Relay relies on TCP to provide error checking in an IP network.

At what layers of the OSI model does Frame Relay operate?
Frame Relay operates at the two lower layers of the OSI model (data link and physical).

What is the difference between switched virtual circuits (SVCs) and permanent virtual circuits (PVCs)?
SVCs are virtual circuits that are dynamically established when data needs to be transferred and that are terminated when data transmission is complete. SVCs consist of four states: call setup, data transfer, idle, and call termination. PVCs are permanently established virtual circuits that operate in one of two states: idle or data transfer. When the PVC is idle, the connection between the DTE devices is still active.

What is a Data Link Connection Identifier (DLCI)?
A DLCI is a number that identifies the logical circuit between the router and the Frame Relay switch. It is the Frame Relay Layer 2 address. The Frame Relay switch maps DLCIs between each pair of routers to create a PVC. For IP devices at the end of each virtual circuit to communicate, their IP addresses need to be mapped to DLCIs. If you are running Cisco IOS 11.2 or later, mapping is done automatically using Inverse ARP. DLCIs have local significance. Think of DLCIs as the MAC address of the Frame Relay network.

What is the committed information rate (CIR)?
The CIR is the committed information rate, by the service provider, in bits per second, at which data will be transferred. The service provider sends any data in excess of this rate if its network has capacity at that time.

How does Frame Relay use Inverse ARP?
Frame Relay uses Inverse ARP as a way to dynamically map a network layer address to a DLCI. With Inverse ARP, the router can discover the network address of a device associated with a VC.

What is the Local Management Interface (LMI)?
The LMI is a signaling standard between a CPE device (a router) and the Frame Relay switch that is responsible for managing and maintaining status between the devices. It is autosensed with Cisco IOS Release 11.2 and later.

In Frame Relay, what is Forward Explicit Congestion Notification (FECN)?
The FECN is the bit in the Frame Relay header that signals to anyone receiving the frame (switches and DTEs) that congestion is occurring in the same direction as the frame. Switches and DTEs can react by slowing the rate at which data is sent in that direction.

What is Backward Explicit Congestion Notification (BECN)?
The BECN is the bit in the Frame Relay header that signals to switches and DTEs receiving the frame that congestion is occurring in the direction opposite (backward) that of the frame. If switches and DTE devices detect that the BECN bit in the Frame Relay header is set to 1, they slow the rate at which data is sent in that direction.

In the Frame Relay header, what is the discard eligibility (DE) bit?
If congestion is detected on the Frame Relay network, the DE bit is turned on in the Frame Relay header. The DE bit is turned on for frames that are in excess of the CIR. The DE bit tells a switch which frames to discard if they must be discarded.

What is the default LMI type for Cisco routers that are configured for Frame Relay?
The default LMI for Cisco routers configured for Frame Relay is Cisco. If you are running Cisco IOS Release 11.2 or later, the Cisco router tries to autosense which LMI type the Frame Relay switch is using. If it cannot autosense the LMI type, the router uses Cisco as its LMI type. The three types of LMIs supported by Cisco routers are:
Cisco
ANSI
Q933a

When a router receives LMI information, it updates its VC status to one of three states. What are these three states?
The three states that a VC uses to update its status are as follows:
Active state The connection is active, and routers can exchange data.
Inactive state The local connection to the Frame Relay switch is working, but the remote router's connection to the Frame Relay switch is not working.
Deleted state Indicates that no LMIs are being received from the Frame Relay switch or that there is no service between the router and the Frame Relay switch.

How do you enable Frame Relay on a Cisco router?
To enable Frame Relay on a Cisco router, you must first enable the serial interface for Frame Relay encapsulation with the encapsulation frame-relay interface command:

RouterB(config)#int s 0

RouterB(config-if)#ip address 192.168.1.1 255.255.255.0

RouterB(config-if)#encapsulation frame-relay

The default encapsulation for a serial interface configured for Frame Relay is cisco. If you are connecting to a non-Cisco router, how do you change the encapsulation type?
If you are connecting to a non-Cisco router in a Frame Relay network, you need to specify ietf as the encapsulation type:

RouterB(config-if)#ip address 192.168.1.1 255.255.255.0

RouterB(config-if)#encapsulation frame-relay ietf

If you are using Cisco IOS Release 11.1 or earlier, or if you do not want to autosense the LMI type, how do you define the LMI type on a Cisco router?
To define the LMI type on a Cisco router, use the frame-relay lmi-type {ansi cisco q933a} interface command:

RouterB(config-if)#ip address 192.168.1.1 255.255.255.0

RouterB(config-if)#encapsulation frame-relay

RouterB(config-if)#frame-relay lmi-type ansi

If Inverse ARP is disabled on your router, how do you reenable it?
Inverse ARP is enabled by default on a Cisco router. If it is disabled, reenable it by using the following command:

RouterB(config-if)#frame-relay inverse-arp [protocol] [dlci]
Supported protocols indicated by the protocol option include ip, ipx, decnet, appletalk, vines, and xns.

If a remote router does not support Inverse ARP, you must define the address-to-DLCI table
statically. How do you create these static maps?
To define static maps on a Cisco router, use the following command:

RouterA(config-if)#frame-relay map protocol protocol-address dlci [broadcast] [ietf cisco] [payload-compress packet-by-packet]

where: · protocol defines the supported protocol bridging or LLC.

· protocol-address is the remote router's network layer address.

· dlci defines the remote router's local DLCI.

· broadcast specifies whether you want to forward broadcasts over the VC, permitting dynamic routing protocols over the VC.· ietf cisco is the encapsulation type.

How do you display the encapsulation type, DLCI, LMI type, and whether the device is a DTE or DCE on a serial interface?
To display the interface's encapsulation type, DLCI number, LMI type, and whether the device is a DTE or DCE, use the show interface interface-type interface-number command: RouterA#show int s0

Serial0 is up, line protocol is up Hardware is HD64570 Internet address is 192.168.1.2/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec) LMI enq sent 3, LMI stat recvd 0, LMI upd recvd 0, DTE LMI up LMI enq recvd 5, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023 LMI type is CISCO frame relay DTE Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0 Last input 00:00:05, output 00:00:07, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair

What Cisco IOS command displays the LMI traffic statistics and LMI type?
The show frame-relay lmi command displays the LMI traffic statistics and LMI type: RouterA#show frame-relay lmi

LMI Statistics for interface Serial0 (Frame Relay DTE)

LMI TYPE = CISCO Invalid Unnumbered info 0

Invalid Prot Disc 0 Invalid dummy Call Ref 0

Invalid Msg Type 0 Invalid Status Message 0

Invalid Lock Shift 0 Invalid Information ID 0

Invalid Report IE Len 0 Invalid Report Request 0

Invalid Keep IE Len 0 Num Status Enq. Rcvd 1748

Num Status msgs Sent 1748 Num Update Status Sent 0

Num St Enq. Timeouts 0

routera#

How do you display the current Frame Relay map entries and information about these connections on a Cisco router?
To view the current map entries and information about the connections, use the show frame-relay map command:

RouterA#show frame-relay map

Serial0 (up): ip 192.168.1.2 dlci 100(0x64,0x1840), dynamic,

Broadcast, status defined, active

How do you clear dynamic Frame Relay maps that were created by Inverse ARP?

Use the clear frame-relay-inarp privileged EXEC command to clear dynamic Frame Relay maps created by Inverse ARP.

QUICK NOTES HOME

Quick Notes - WAN

2007-07-01T01:46:00.000-07:00

The three WAN connection types available are leased lines, circuit-switched, and packet-switched. Define the differences between each connection type.
Leased lines are dedicated point-to-point lines that provide a single preestablished WAN communication path from the customer's network to the remote network. Leased lines are usually employed over synchronous connections. They are generally expensive and are always up. Circuit-switched connections are dedicated for only the duration of the call. The telephone system and ISDN are examples of circuit-switched networks. Packet-switched connections use virtual circuits (VCs) to provide end-to-end connectivity. Packet-switched connections are similar to leased lines, except that the line is shared by other customers. A packet knows how to reach its destination by programming of switches. Frame Relay is an example of a packet-switched connection.

Define customer premises equipment (CPE), and give an example.
CPE is equipment that is located on the customer's (or subscriber's) premises. It is equipment owned by the customer or equipment leased by the service provider to the customer. An example is your router.

What is the demarcation point (demarc)?
The demarc is the point where the CPE ends and the local loop begins. It is the last responsibility of the service provider and is usually an RJ-45 jack located close to the CPE. Think of the demarc as the boundary between the customer's wiring and the service provider's wiring.

What is the local loop?
The local loop is the physical cable that extends from the demarc to the central office.

Describe the central office (CO).
The CO is the telco switching facility that connects the customer to the provider's switching network. The CO is sometimes referred to as a point of presence. It is the point where the local loop gains access to the service provider's access lines.

What is the toll network?
All the telco switches, COs, and trunk lines inside the WAN provider's network are the toll network.

What are synchronous links?
Synchronous links have identical frequencies and contain individual characters encapsulated in control bits, called start/stop bits, that designate the beginning and end of each character. Synchronous links try to use the same speed as the other end of a serial link.

What are asynchronous links?
Asynchronous links send digital signals without timing. Asynchronous links agree on the same speed, but there is no check or adjustment of the rates if they are slightly different. Only 1 byte per transfer is sent.

List some typical Layer 2 encapsulation methods for WAN links.
. High-Level Data Link Control (HDLC)
· Point-to-Point Protocol (PPP)
· Serial Line Internet Protocol (SLIP)
· X.25/Link Access Procedure, Balanced (LAPB)
· Frame Relay· Asynchronous Transfer Mode (ATM)

Describe HDLC.
HDLC was derived from Synchronous Data Link Control (SDLC). It is the default encapsulation type on point-to-point dedicated links and circuit-switched connections between Cisco routers. It is an ISO-standard bit-oriented data-link protocol that encapsulates data on synchronous links. HDLC is a connection-oriented protocol that has very little overhead. HDLC lacks a protocol field and therefore cannot encapsulate multiple network layer protocols across the same link. Because of this, each vendor has its own method of identifying the network-layer protocol. Cisco offers a propriety version of HDLC that uses a type field that acts as a protocol field, making it possible for multiple network-layer protocols to share the same link.

By default, Cisco uses HDLC as its default encapsulation method across synchronous lines (point-to-point links). If a serial line uses a different encapsulation protocol, how do you change it back to HDLC?
To change a serial line back to HDLC, use the following interface command on the serial interface you want to change: Router(config-if)#encapsulation hdlc

What is the Point-to-Point Protocol (PPP)?
PPP is an industry-standard protocol that provides router-to-router or router-to-host connections over synchronous and asynchronous links. It can be used to connect to other vendors' equipment. It works with several network-layer protocols, such as IP and IPX. PPP provides authentication through PAP or CHAP.

Describe X.25/LAPB.
X.25/LAPB is an ITU-T standard that has a tremendous amount of overhead because of its strict timeout and windowing techniques. LAPB is the connection-oriented protocol used with X.25. It uses the ABM (Asynchronous Balance Mode) transfer mode. X.25/LAPB was used in the 1980s when WAN links were not as error-free as they are today. X.25 is a predecessor of Frame Relay. X.25 supports both switched and permanent virtual circuits.

What is Frame Relay?
An industry standard, Frame Relay is a switched data link layer protocol that uses virtual circuits to identify the traffic that belongs to certain routers. It provides dynamic bandwidth allocation and congestion control.

How do you view the encapsulation type on a serial interface?
To view the encapsulation type on a serial interface, use the show interface serial interface-number command:
RouterB#show interface serial 0
Serial0 is up, line protocol is up Hardware is HD64570
Internet address is 192.168.1.1/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:00, output 00:00:03, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
9 packets input, 1730 bytes, 0 no buffer
Received 8 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
7 packets output, 1584 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 output buffer failures, 0 output buffers swapped out
5 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up

QUICK NOTES HOME

Quick Notes - LAN

2007-06-30T23:46:00.000-07:00

What is carrier sense multiple access collision detect (CSMA/CD)?
CSMA/CD describes the Ethernet access method. In CSMA/CD, many stations can transmit on the same cable, and no station has priority over any other. Before a station transmits, it listens on the wire to make sure no other station is transmitting. If no other station is transmitting, the station transmits across the wire. CSMA/CD is all about devices taking turns using the wire.

What are MAC addresses?
For computers to identify each other on the data link layer, they need a MAC address (hardware address). All devices on a LAN must have a unique MAC address. A MAC address is a 48-bit (six octet) address burned into a network interface card. The first three octets (24 bits) of the MAC address indicate the vendor that manufactured the card. This is called the Organization Unique Identifier (OUI). The last three octets of the MAC address are the unique host address. An example of a MAC address is 00-80-C6-E7-9C-EF.

What are the three types of LAN traffic?
The three types of LAN traffic are:
Unicasts
Broadcasts
Multicasts

What are unicast frames?
Unicast frames are the most common type of LAN traffic. A unicast frame is a frame intended for only one host. In unicast frames, the only station that processes the frame is the station that has its own MAC address in the destination portion of the packet.

What are broadcast frames?
Broadcast frames are frames intended for everyone. Stations view broadcast frames as public service announcements. All stations receive and process broadcast frames. In large networks, broadcasts can bring the network to a crawl, because every computer must process them.

What is the destination address of broadcast frames?
The destination address of broadcast frames (Layer 2 broadcast addresses) is FF-FF-FF-FF-FF-FF, or all 1s in binary.

What are multicast frames?
Multicast frames address a group of devices that have a common interest. These frames allow the source to send only one copy of the frame on the network even though it is intended for several stations. Only stations that have a card that is configured to receive multicast frames process them. All other stations discard multicast frames.

What devices can you use to segment a LAN at Layer 1, Layer 2, and Layer 3?
Three devices you can use to segment a LAN are:
Hubs/repeaters (Layer 1)
Bridges/switches (Layer 2) - physical addresses
Routers (Layer 3) - logical addresses

What happens when you segment the network with hubs/repeaters?
Because hubs and repeaters operate at the physical layer of the OSI model, segmenting a network with these devices appears as an extension to the physical cable. Hubs and repeaters are transparent to devices. They are unintelligent devices. All devices that connect to a hub/repeater share the same bandwidth. Hubs/repeaters create a single broadcast and collision domain.

What is the advantage of segmenting a network with bridges/switches?
Bridges/switches operate at Layer 2 of the OSI model and filter by MAC address. Each port on a bridge/switch provides full-dedicated bandwidth and creates a single collision domain. Because bridges/switches operate at Layer 2 of the OSI model, they cannot filter broadcasts, and they create a single broadcast domain. For the CCNA test, remember that switches create more collision domains and fewer collisions.

What is the difference between bridges and switches?
Bridges and switches function the same way; the only difference is in how they are implemented. Bridges are implemented by software and usually have a couple of network ports. Switches are implemented in hardware by ASIC chips and have many ports.

What are the advantages and disadvantages of segmenting the LAN with routers?
An advantage of segmenting the LAN with routers is that each interface on a router creates a single broadcast and collision domain. Routers operate at Layer 3 of the OSI model and do not propagate broadcasts. Some disadvantages are that routers are not transparent and are implemented in software, thus introducing latency in the network.

What is the Maximum Transmission Unit (MTU) for an Ethernet frame?
1500 bytes is the MTU for an Ethernet frame. You will notice that some publications state that the MTU for Ethernet is 1518 bytes. This is correct also. But what is the true answer? The MTU for Ethernet, including the header, source and destination address, data, and CRC is 1518 bytes. The MTU for the data portion of the frame is 1500 bytes.

What three major functions do Layer 2 switches provide?
The three major functions that Layer 2 switches provide are
Address learning
Packet forwarding/filtering
Loop avoidance by spanning tree

What are some advantages of switches?
Some advantages of switches are as follows:
They increase available network bandwidth.
They reduce the number of users per segment.
They provide dedicated bandwidth to each segment.
Transparent bridging (switching) provides five bridging functions to determine what to do when it receives a frame.

What are these five processes?
The five processes are:
Learning
Flooding
Filtering
Forwarding
Aging

In transparent bridging, what is the learning process?
The first process a bridge goes through when it is powered on is the learning process. The MAC address table on the bridge contains no entries, and the bridge goes through the learning process to record all workstations on every interface. In the learning process, the bridge records the source MAC address and source port number in the MAC address table every time it sees a frame.

In transparent bridging, what is the flooding process?
When a bridge is first turned on, it has no MAC address in its table. When a switch receives a unicast frame, it knows the source address and port from which the unicast frame came, but no entry exists in its table for the destination address. This is called an unknown unicast frame. When a switch receives an unknown unicast frame, it sends the frame out all forwarding interfaces on the bridge except the interface that received the frame. This process is the flooding process.

In transparent bridging, what is the filtering process?
The filtering process occurs when the source and destination addresses reside on the same interface on the bridge. Because the bridge does not need to forward a frame in which the destination and source addresses reside on the same interface, it filters the frame and discards it.

In transparent bridging, what is the forwarding process?
The forwarding process occurs when a switch receives a unicast frame and has an entry of the destination address in its MAC table. The switch then forwards the frame to the interface where that destination address resides.

In transparent bridging, what occurs during the aging process?
Every time a bridge learns a source address, it time-stamps the entry. When the bridge sees a frame from this source, it updates the time stamp. If the bridge does not hear from the source for a specific amount of time (called the aging timer), the bridge deletes the entry from its MAC address table. This process is the aging process.

What is the default aging time in transparent bridges?
The default aging timer is 5 minutes.

What is the Spanning-Tree Protocol (STP)?
STP is a loop-prevention bridge-to-bridge protocol. Its main purpose is to dynamically maintain a loop-free network. It does this by sending out Bridge Protocol Data Units (BPDUs), discovering any loops in the topology, and blocking one or more redundant links.

How does STP maintain a loop-free network?
STP maintains a loop-free network by
Electing a root bridge
Electing a root port on each nonroot bridge
Electing designated ports
Putting in the blocking state any port that is not a root port or designated port

What two key concepts does STP calculation use to create a loop-free topology?
The two key concepts that STP uses to calculate a loop-free topology are
Bridge ID (BID)
Path cost

In spanning tree, what is a Bridge ID (BID)?
A BID is an 8-byte field that is composed of the bridge's 6-byte MAC address and a 2-byte bridge priority.

What is the default bridge priority in a Bridge ID for all Cisco switches?
32,768

In spanning tree, what is path cost?
Path cost is a calculation to determine the link's bandwidth. It is a value assigned to each port that is based on the port's speed.

What is the spanning tree path cost for each of the following?
10 Mbps
100 Mbps
1 Gbps
The path costs are as follows:
10 Mbps - 100
100 Mbps - 19
1 Gbps - 4

When calculating a loop-free environment, what four-step decision sequence does spanning tree use to determine what will be the root bridge and which ports will forward or block?
The four-step decision sequence that spanning tree uses to determine the root bridge and which port will forward is as follows:
Step 1. The lowest root BID
Step 2. The lowest path cost to the root bridge
Step 3. The lowest sender BID
Step 4. The lowest port ID

How do bridges pass spanning tree information between themselves?
Bridges pass STP information using special frame called Bridge Protocol Data Units (BPDUs).

How often do bridges send BPDUs out active ports?
The default time that bridges send BPDUs out active ports is 2 seconds.
Note: All ports on a switch listen for BPDUs in case there is a topology change.

In STP, how is a root bridge elected?
In STP, the bridge with the lowest BID is elected the root bridge. All ports on the root bridge are placed in the forwarding state and are called designated ports.
Note: The BID is a 6-byte field that is composed of a default priority (32,768) and a MAC address. Because all Cisco switches use the default priority, the switch with the lowest MAC address is elected the root bridge. As a rule of thumb, lower will always win in spanning tree.

After bridges elect the root bridge, what do they do next?
After electing the root bridge, switches elect root ports. A root port is the port on nonroot bridges that is closest to the root bridge. Every nonroot bridge must select one root port.

How do nonroot bridges decide which port they will elect as a root port?
Nonroot bridges use root path cost to determine which port will be the root port. Root path cost is the cumulative cost of all links to the root bridge. The port with the lowest root path cost is elected the bridge's root port and is placed in the forwarding state.

What is the difference between path cost and root path cost?
Path cost is the value assigned to each port. It is added to BPDUs received on that port to calculate the root path cost. Root path cost is defined as the cumulative cost to the root bridge. In a BPDU, this is the value transmitted in the cost field. In a bridge, this value is calculated by adding the receiving port's path cost to the value contained in the BPDU.

If a nonroot bridge has two redundant ports with the same root path cost, how does the bridge choose which port will be the root port?
If a nonroot bridge has redundant ports with the same root path cost, the deciding factor is the port with the lowest port ID (port number).

After the root bridge and root ports are selected, the last step in spanning tree is to elect designated ports. How do bridges elect designated ports?
In spanning tree, each segment in a bridged network has one designated port. This port is a single port that both sends and receives traffic to and from that segment and the root bridge. All other ports are placed in a blocking state. This ensures that only one port on any segment can send and receive traffic to and from the root bridge, ensuring a loop-free topology. The bridge containing the designated port for a segment is called the designated bridge for that segment. Designated ports are chosen based on cumulative root path cost to the root bridge.
Note: Every active port on the root bridge becomes a designated port.

If a bridge is faced with a tie in electing designated ports, how does it decide which port will be the designated port?
In the event of a tie, STP uses the four-step decision process discussed in Question 30. It first looks for the BPDU with the lowest BID; this is always the root bridge. If the switch is not the root bridge, it moves to the next step: the BPDU with the lowest path cost to the root bridge. If both paths are equal, STP looks for the BPDU with the lowest sender BID. If these are equal, STP uses the link with the lowest port ID as the final tiebreaker.

What are the four spanning tree port states?
The four spanning tree port states are
Blocking
Listening
Learning
Forwarding
Remember that root and designated ports forward traffic and that nondesignated ports block traffic but still listen for BPDUs.
Important note: There is another port state - Disabled - (No frames forwarded, no BPDUs heard). If it shows up in the answer options - select it along with the others.

What is the STP blocking state?
When a switch starts, all ports are in the blocking state. This is to prevent any loops in the network. If there is a better path to the root bridge, the port remains in the blocked state. Ports in the blocked state cannot send or receive traffic, but they can receive BPDUs.

What is the STP listening state?
Ports transition from a blocked state to a listening state. In this state, no user data is passed. The port only listens for BPDUs. After listening for 15 seconds (if the bridge does not find a better path), the port moves to the next state, the learning state.

What is the STP learning state?
In the STP learning state, no user data is being passed. The port quietly builds its bridging table. The default time in the learning state is 15 seconds.

What is the STP forwarding state?
After the default time in the learning state is up, the port moves to the forwarding state. In the forwarding state, the port sends and receives data.

What is STP forward delay?
The forward delay is the time it takes for a port to move from the listening state to the learning state or from the learning state to the forwarding state. The default time is 30 seconds.

What is the hello time in STP timers?
The hello time is the time interval between the sending of BPDUs. The default time is 2 seconds.

What is the Max Age timer?
The Max Age timer is how long a bridge stores a BPDU before discarding it. The default time is 20 seconds (ten missed hello intervals).

What is the default time a port takes to transition from the blocking state to the forwarding state?
The default time a port takes to transition from the blocking state to the forwarding state is 50 seconds: 20 seconds for Max Age, 15 seconds for listening, and 15 seconds for learning.

What does STP do when it detects a topology change in the network due to a bridge or link failure?
If spanning tree detects a change in the network due to a bridge or link failure, at least one bridge interface changes from the blocking state to the forwarding state, or vice versa.

QUICK NOTES HOME

Quick Notes - CABLING TECHNOLOGY

2007-06-30T23:37:00.000-07:00

What is a straight-through cable, and when would you use it?
A straight-through cable is the same at both ends. A straight-through cable uses pins 1, 2, 3, and 6. The send and receive wires are not crossed. You should use a straight-through cable when connecting dissimilar devices. Examples include connecting PCs to switches or hubs or a router to a switch or a hub.

What is a crossover cable, and when would you use it?
A crossover cable is a cable that has the send and receive wires crossed at one of the ends. On a Category 5 cable, the 1 and 3 wires and the 2 and 6 wires are switched on one of the cable's ends. You should use a crossover cable when connecting similar devices, such as connecting a router to a router, a switch to a switch or hub, a hub to a hub, or a PC to a PC.
Important tip -- Router (think of it as a PC) to PC via 10BaseT (NIC) uses a "crossover cable". (contradicts the rule)

How do you set up a console session to a Cisco device?
To set up a console session to a Cisco device, you connect a rollover cable to the console port on the Cisco device. You then connect the other end to your PC and configure a terminal emulation application to the following com settings: 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow control.

What is the maximum cable length for each of the following?
10Base2
10Base510
BaseT
10BaseFL
100BaseT
The maximum cable lengths are as follows:
10Base2 (thinnet) 185 meters
10Base5 (thicknet) 500 meters
10BaseT 100 meters
10BaseFL 2000 meters (400 meters in a shared environment and 2000 meters in a point-to-point environment)
100BaseT 100 meters

What does Base stand for in 10BaseT and 100BaseT?
Base in 10BaseT and 100BaseT stands for baseband. Baseband is a network technology in which only one carrier frequency (signal) is used.

What is the difference between baseband and broadband?
Baseband is a network technology in which only one carrier frequency is used (such as Ethernet). Broadband is a network technology in which several independent channels are multiplexed into one cable (for example, a T1 line).

QUICK NOTES HOME

Quick Notes - ACCESS LISTS

2007-06-30T01:33:00.000-07:00

Besides named access lists, what are the two types of IP access lists?
The two types of IP access lists are standard and extended.

What criteria do standard IP access lists use to filter packets?
Standard IP access lists filter packets by the source address. This results in the packet's being permitted or denied for the entire protocol suite based on the source network IP address.

What criteria do extended IP access lists use to filter packets?
Extended IP access lists filter packets by source address, destination address, protocols, and port numbers.

In what two ways can IP access lists be applied to an interface?
Access lists can be applied as inbound or outbound access lists. Inbound access lists process packets as they enter a router's interface and before they are routed. Outbound access lists process packets as they exit a router's interface and after they are routed.

How many access lists can be applied to an interface on a Cisco router?
Only one access list per protocol, per direction, per interface can be applied on a Cisco router. Multiple access lists are permitted per interface, but they must be for a different protocol.

How are access lists processed?
Access lists are processed in sequential, logical order, evaluating packets from the top down, one statement at a time. As soon as a match is made, the permit or deny option is applied, and the packet is not applied to any more access list statements. Because of this, the order of the statements within any access list is significant.

What is at the end of each access list?
At the end of each access list, an implicit deny statement denies any packet not filtered in the access list.

What are the number ranges used to define standard and extended IP access lists?
The number ranges used to define standard and extended IP access lists are as follows:
· Standard IP access lists 1 to 99 and 1300 to 1999· Extended IP access lists 100 to 199 and 2000 to 2699

When implementing access lists, what are wildcard masks?
Wildcard masks define the subset of the 32 bits in the IP address that must be matched. Wildcards are used with access lists to specify a host, network, or part of a network. Wildcard masks work exactly the opposite of subnet masks. In subnet masks, 1 bits are matched to the network portion of the address, and 0s are wildcards that specify the host range. In wildcard masks, when 0s are present, the octet address must match. Mask bits with a binary value of 1 are wildcards. For example, if you have an IP address 172.16.0.0 with a wildcard mask of 0.0.255.255, the first two portions of the IP address must match 172.16, but the last two octets can be in the range 1 to 255.

What is the IOS command syntax used to create a standard IP access list?
Here is the command syntax to create a standard IP access list:
access-list access-list-number {permit deny} source-address [wildcard mask]access-list-number is a number from 1 to 99.
For example:
RouterA(config)#access-list 10 deny 192.168.0.0 0.0.0.255

After you create a standard or extended IP access list, how do you apply it to an interface on a Cisco router?
To apply an access list to an interface on a Cisco router, use the ip access-group interface command: ip access-group access-list-number {in out}For example:RouterA(config)#int s0RouterA(config-if)#ip access-group 10 in
Create a standard access list that permits the following networks:
192.168.200.0192.168.216.0192.168.232.0192.168.248.0
There are two ways to do this. First, you can create one access list that contains an entry for each network:
access-list 10 permit 192.168.200.0 0.0.0.255access-list 10 permit 192.168.216.0 0.0.0.255access-list 10 permit 192.168.232.0 0.0.0.255access-list 10 permit 192.168.248.0 0.0.0.255
A second way to do this is to create a single entry with wildcard masks:
access-list 10 permit 192.168.200.0 0.0.48.255
To see how this one statement denies all the networks, you must look at it in binary:
.200= 11001000.216= 11011000.232= 11101000.248= 11111000
All the bits match except the third and fourth bits. With wildcard masks, these are the bits you want to match. Therefore, your wildcard mask would be 00110000 in binary, which is 48.

What is the Cisco IOS command syntax used to create an extended access list?
Here is the Cisco IOS command syntax to create an extended access list: access-list access-list-number {permit deny} protocol source-address source-wildcard [operator port] destination-address destination-wildcard [operator port]
protocol examples include IP, TCP, UDP, ICMP, GRE, and IGRP.
operator port can be lt (less than), gt (greater than), eq (equal to), or neg (not equal to) and a protocol port number.
Create an extended access list denying web traffic to network 192.168.10.0.
The following commands deny web traffic to network 192.168.10.0:
access-list 101 deny tcp any 192.168.10.0 0.0.0.255 eq wwwaccess-list 101 permit ip any any

What IOS command can you use to see whether an IP access list is applied to an interface?
The IOS command to see whether an IP access list is applied to an interface is
show ip interface interface-type interface-number
For example:
RouterA#show ip interface s0
Serial0 is up, line protocol is up Internet address is 192.168.1.2/24 Broadcast address is 255.255.255.255 Address determined by non-volatile memory MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Multicast reserved groups joined: 224.0.0.9 Outgoing access list is not set Inbound access list is 10 Proxy ARP is enabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is enabled IP Feature Fast switching turbo vector IP multicast fast switching is disabled IP multicast distributed fast switching is disabled IP route-cache flags are Fast Router Discovery is disabled IP output packet accounting is disabled IP access violation accounting is disabled TCP/IP header compression is disabled RTP/IP header compression is disabled Probe proxy name replies are disabled Policy routing is disabled Network address translation is disabled Web Cache Redirect is disabled BGP Policy Mapping is disabled

How can you display all access lists on a Cisco router?
To display all access lists on a Cisco router, use the show access-list command: RouterA#show access-listStandard IP access list 10 deny 192.168.0.0, wildcard bits 0.0.0.255Extended IP access list 101 permit tcp any any eq www permit udp any any eq domain permit udp any eq domain any permit icmp any any deny tcp 192.168.10.0 0.0.0.255 any eq wwwRouterA#

How do you figure out wildcard questions?
Identify the class192.68.12.0 - Class C24 bits for networks/29 tells us that we need an additional 5 bits29 - 24 = 5 bits5 bits = 128 + 64 + 32 + 16 + 8 = 248Default subnet mask for Class C network = 255.255.255.0New subnet mask for /29 network = 255.255.255.248To find the wildcard value:255.255.255.255 255.255.255.248
- ---------------
0.0.0.7Same logic for Class B172.31.0.0 /1916 bits for networks/19 tells us we need an additional 3 bits19 - 16 = 3 bits3 bits = 128 + 64 + 32 = 224Default subnet mask for Class B network = 255.255.0.0New subnet mask for /19 network = 255.255.224.0To find the wildcard value:255.255.255.255255.255.224.0 ----------------0.0.31.255 ´

QUICK NOTES HOME

CCNA Exam Topic: Implementation & Operations - 2

2007-05-20T02:57:00.000-07:00

Continuation of Implementation & Operations CCNA actual exam topic questions.

Question 21:
A network administrator is configuring the routers in the graphic for OSPF. The OSPF process has been started and the networks have been configured for Area 0 as shown in the diagram. The network administrator has several options for configuring RouterB to ensure that it will be preferred as the designated router (DR) for the 172.16.1.0 /24 LAN segment. What configuration tasks could be used to establish this preference? (Choose three.)

A. Configure the priority value of the Fa0/0 interface of RouterB to a higher value than any other interface on the Ethernet network.
B. Change the router id of Router B by assigning the IP address 172.16.1.130/24 to the Fa0/0 interface of RouterB.
C. Configure a loopback interface on RouterB with an IP address higher than any IP address on the other routers.
D. Change the priority value of the Fa0/0 interface of RouterB to zero.
E. Change the priority values of the Fa0/0 interfaces of RouterA and RouterC to zero.
F. No further configuration is necessary.

Answer: ACE

Question 22:
Refer to the graphic. Two 2950 switches connect through ports Fa0/24 and a straight-through cable. Based on the output of the show cdp neighbor command from both switches and the information given, what can be concluded?
A. Port Fa0/24 on each switch must be configured in VLAN 1 in order for the switches to see neighbor information.
B. Port Fa0/24 on each switch must be configured as a trunk port in order for neighbor information to be received.
C. The switches are not cabled properly.
D. An IP address needs to be assigned to both switches.
E. VTP is incorrectly configured on switch A.

Answer: C

Question 23:
Refer to the topology and router configuration shown in the graphic. A host on the LAN is accessing an FTP server across the Internet. Which of the following addresses could appear as a source address for the packets forwarded by the router to the destination server?
A. 10.10.0.1
B. 10.10.0.2
C. 199.99.9.33
D. 199.99.9.57
E. 200.2.2.17
F. 200.2.2.18

Answer: D

Question 24:
Refer to the graphic. A company wants to use NAT in the network shown. Which commands will apply the NAT configuration to the proper interfaces? (Choose two.)
A. R1(config)# interface serial0/1
R1(config-if)# ip nat inside
B. R1(config)# interface serial0/1
R1(config-if)# ip nat outside
C. R1(config)# interface fastethernet0/0
R1(config-if)# ip nat inside
D. R1(config)# interface fastethernet0/0
R1(config-if)# ip nat outside
E. R1(config)# interface serial0/1
R1(config-if)# ip nat outside source pool 200.2.2.18 255.255.255.252
F. R1(config)# interface fastethernet0/0
R1(config-if)# ip nat inside source 10.10.0.0 255.255.255.0

Answer: BC

Question 25:
Refer to the graphic. Which of the following commands would create the output shown at the bottom of the graphic?
A. Router# show ip eigrp topology
B. Router# show ip route
C. Router# show ip eigrp neighbors
D. Router# show ip ospf route
E. Router# show ip ospf database

Answer: A

Question 26:
Refer to the exhibit. Which ports could safely be configured with PortFast? (Choose two.)

A. Switch1 - port Fa1/2
B. Switch2 - port Fa1/2
C. Switch1 - port Fa1/3
D. Switch2 - port Fa1/3
E. Switch1 - port Fa1/1
F. Switch2 - port Fa1/1

Answer: CD

Question 27:
Refer to the exhibit. Communication with the Internet is vital to all networks belonging to the corporation. On which of the four routers shown in the graphic should a default route be configured, assuming that a routing protocol is being used to distribute the default route? A. A
B. B
C. C
D. ISP

Answer: A

Question 28:
Refer to the graphic. It has been decided that Workstation 1 should be denied access to Server1. Which of the following commands are required to prevent only Workstation 1 from accessing Server1 while allowing all other traffic to flow normally? (Choose two.)

A. RouterA(config)# interface fa0/0
RouterA(config-if)# ip access-group 101 out
B. RouterA(config)# interface fa0/0
RouterA(config-if)# ip access-group 101 in
C. RouterA(config)# access-list 101 deny ip host 172.16.161.150 host 172.16.162.163
RouterA(config)# access-list 101 permit ip any any
D. RouterA(config)# access-list 101 deny ip 172.16.161.150 0.0.0.255 172.16.162.163 0.0.0.0
RouterA(config)# access-list 101 permit ip any any

Answer: BC

Question 29:
Refer to the topology and command output within the exhibit. When hosts on the 172.16.5.0 network attempt to ping the remote server at 192.168.145.27, the message "Reply from 192.168.145.27:TTL expired in transit" is returned. What is the cause of this problem?

A. No static route is configured on the SOHO router to the 192.168.145.0 network.
B. No static route is configured on the ISP router to the 192.168.145.0 network.
C. A routing protocol must be configured to send packets between SOHO and ISP.
D. A routing loop has occurred.

Answer: D

Question 30:
Refer to graphic and examine the output from the London switch . What VTP functions will this switch perform?
A. create, change, and delete VLANs for the VTP domain
B. learn and save VTP configuration information in the running configuration only
C. forward VTP configuration information
D. backup the VTP database for the closest VTP server
E. prevent VTP information from reaching workgroup switches

Answer: C

Question 31:
Refer to the exhibit. Based on the exhibited routing table, how will packets from a host within the 192.168.10.192/26 LAN be forwarded to 192.168.10.1?
A. The router will forward packets from R3 to R2 to R1.
B. The router will forward packets from R3 to R1 to R2.
C. The router will forward packets from R3 to R2 to R1 AND from R3 to R1.
D. The router will forward packets from R3 to R1.

Answer: C

Question 32:
A network administrator needs to verify that switch interface 0/5 has been assigned to the Sales VLAN. Which command will accomplish this task?

A. show vlan
B. show mac-address-table
C. show vtp status
D. show spanning-tree root
E. show ip interface brief

Answer: A

Question 33:
Refer to the exhibit. Host A needs to send data to Host B. Which Layer 2 and Layer 3 destination addresses will be used to send the data from Host A to Host B?
A. 192.168.60.5 and 0011.43da.2c98
B. 192.168.60.5 and 0007.0e56.ab2e
C. 192.168.24.1 and 0007.0e56.ab2e
D. 192.168.24.2 and 0007.0e84.acef

Answer: B

Question 34:
Refer to the exhibit. What is the correct addressing for a frame and packet received by Host B from Host A?

A. Destination MAC: 0011.43da.2c98
Source MAC: 0070.0e8f.088a
Destination IP: 192.168.60.5
Source IP: 192.168.24.5
B. Destination MAC: 0011.43da.2c98
Source MAC: 00b0.d0ef.5f6a
Destination IP: 192.168.60.5
Source IP: 192.168.24.5
C. Destination MAC: 0011.43da.2c98
Source MAC: 0070.0e8f.088a
Destination IP: 192.168.60.5
Source IP: 192.168.60.1
D. Destination MAC: 0011.43da.2c98
Source MAC: 0070.0e97.af4e
Destination IP: 192.168.60.5
Source IP: 192.168.60.2

Answer: A

Question 35:

Refer to the exhibit. Switch-1 needs to send data to a host with a MAC address of 00b0.d056.efa4. What will Switch-1 do with this data?

A. Switch-1 will drop the data because it does not have an entry for that MAC address.
B. Switch-1 will flood the data out all of its ports except the port from which the data originated.
C. Switch-1 will send an ARP request out all its ports except the port from which the data originated.
D. Switch-1 will forward the data to its default gateway.

Answer: B

Question 36:
Why has the network shown in the exhibit failed to converge?
A. The no auto-summary command needs to be applied to the routers.
B. The network numbers have not been properly configured on the routers.
C. The subnet masks for the network numbers have not been properly configured.
D. The autonomous system number has not been properly configured.
E. The bandwidth values have not been properly configured on the serial interfaces.

Answer: A

Question 37:
Refer to the exhibit. A network associate has configured OSPF with the command:
City(config-router)#network 192.168.12.64 0.0.0.63 area 0
After completing the configuration, the associate discovers that not all the interfaces are participating in OSPF. Which three of the interfaces shown in the exhibit will participate in OSPF according to this configuration statement? (Choose three.)
A. FastEthernet0 /0
B. FastEthernet0 /1
C. Serial0/0
D. Serial0/1.102
E. Serial0/1.103
F. Serial0/1.104

Answer: BCD

Question 38:
Refer to the exhibit. What can be determined about the interfaces of the Main_Campus router from the output shown?
A. The LAN interfaces are configured on different subnets.
B. Interface FastEthernet 0/0 is configured as a trunk.
C. The Layer 2 protocol of interface Serial 0/1 is NOT operational.
D. The router is a modular router with five FastEthernet interfaces.
E. Interface FastEthernet 0/0 is administratively deactivated.

Answer: B

Question 39:
Refer to the output of the two show commands in the exhibit. If an administrator tries to ping host 10.1.8.5 from host 10.1.6.100, how will the ICMP packets be processed by Router A?
A. The packets will be discarded.
B. The packets will be routed out the S0/0 interface.
C. The packets will be routed out the S0/1 interface.
D. The packets will be routed out the Fa0/0 interface.

Answer: C

Question 40:
Refer to the exhibit. Assuming that the entire network topology is shown, what is the operational status of the interfaces of R2 as indicated by the command output shown?
A. One interface has a problem.
B. Two interfaces have problems.
C. The interfaces are functioning correctly.
D. The operational status of the interfaces cannot be determined from the output shown.

Answer: C

Question 41:
Refer to the exhibit. A network technician is asked to design a small network with redundancy. The exhibit represents this design, with all hosts configured in the same VLAN. What conclusions can be made about this design?
A. This design will function as intended.
B. Spanning-tree will need to be used.
C. The router will not accept the addressing scheme.
D. The connection between switches should be a trunk.
E. The router interfaces must be encapsulated with the 802.1Q protocol.

Answer: C

Question 42:
A company is experiencing network delays. The network administrator discovers that a worker in a location far from the MDF has connected an old 10BASE-T switch with redundant links to the existing network. How could this action be responsible for the impaired network performance?

A. Connecting a host to the old switch has created a broadcast storm.
B. The 10BASE-T switch forced the entire network to be reduced to 10 Mbps operation.
C. The old switch does not support VLANs, which has disabled the VLAN configuration of the entire the network.
D. The old switch does not support full-duplex operation, effectively forcing half-duplex operation throughout the network.
E. Spanning Tree Protocol has elected the old switch as the root bridge, creating inefficient data paths through the switched network.

Answer: E

Question 43:
Refer to the exhibit. What does STATUS=ACTIVE refer to in the output of the show frame-relay pvc command?
A. The PVC is experiencing congestion.
B. The Frame Relay switch is correctly programmed with the DLCI and is operational.
C. The router is actively broadcasting to establish a link to the Frame Relay switch.
D. The router is connected to the local Frame Relay switch, but not to the far end device.

Answer: B

Question 44:
Refer to the exhibit. The Lakeside Company has the internetwork in the exhibit. The administrator would like to reduce the size of the routing table on the Central router. Which partial routing table entry in the Central router represents a route summary that represents the LANs in Phoenix but no additional subnets?
A. 10.0.0.0/22 is subnetted, 1 subnets
D10.0.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
B. 10.0.0.0/28 is subnetted, 1 subnets
D10.2.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
C. 10.0.0.0/30 is subnetted, 1 subnets
D10.2.2.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
D. 10.0.0.0/22 is subnetted, 1 subnets
D10.4.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
E. 10.0.0.0/28 is subnetted, 1 subnets
D10.4.4.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
F. 10.0.0.0/30 is subnetted, 1 subnets
D 10.4.4.4 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1

Answer: D

Question 45:
Refer to the exhibit. Which two statements describe the OSPF relationships between the routers? (Choose two.) A. R3 is fully adjacent with R2 and is the DR for the 192.168.2.4 network.
B. R3 is fully adjacent with R1 and is the DR for the 10.1.1.0 network.
C. R3 is fully adjacent with R2 and is the BDR for the 10.1.1.0 network.
D. R2 is fully adjacent with R1 and is the BDR for the 10.1.1.0 network.
E. R3 is fully adjacent with routers R1 and R2
F. R2 is the DR for networks 192.168.1.0 and 172.16.2.0.

Answer: BE

Question 46:
Based on the topology table that is shown in the exhibit and assuming that variance is not configured for EIGRP, which route or routes should appear in the routing table?

A. D 192.168.8.20 (2707456/2195456), Serial0/1
B. D 192.168.2.0/24 [90/2707456] via 192.168.8.22, 00:27:50, Serial0/0
[90/3815424] via 192.168.8.18, 00:27:50, Serial0/2
C. D 192.168.2.0/24 [90/3815424] via 192.168.8.18, 00:27:50, Serial0/2
D. D 192.168.8.24/30 [90/2681856] via 192.168.8.22, 00:27:50, Serial0/0

Answer: D

Question 47:
Refer to the exhibit. The network has been configured with STP disabled. HostA sends an ARP request for the IP address of a site on the Internet. What will happen to this ARP request? (Choose two.)
A. Because the ARP request is a broadcast, SW-A will not forward the request.
B. SW-A will convert the broadcast to a unicast and forward it to SW-D.
C. The switches will propagate the broadcast, creating a broadcast storm.
D. From a port on SW-A, HostA will receive an ARP reply containing the MAC address.
E. From the Ethernet interface of RouterX, HostA will receive an ARP reply that contains the MAC address.
F. The switches will propagate the broadcast until the TTL of the frame reduces to 0. Then the frame will be discarded.

Answer: CE

Question 48:
Refer to the exhibit. Spanning Tree Protocol has created a loop-free logical topology in the network that is pictured. How many ports have been placed in the blocking mode?
A. none
B. one
C. two
D. three
E. four

Answer: C

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CCNA Exam Topic: Implementation & Operation

2007-05-12T04:34:00.001-07:00

CCNA Implementation & Operations topic explains all the actual and real questions that would be on ccna test.

Question 1:
What is a global command?
A. a command that is available in every release of IOS, regardless of the version or deployment status
B. a command that can be entered in any configuration mode
C. a command that is universal in application and supports all protocols
D. a command that is implemented in all foreign and domestic IOS versions
E. a command that is set once and affects the entire router

Answer: E

Question 2:
The Ethernet 0 interface of a router was configured with address 10.64.0.1 255.224.0.0 while the Ethernet 1 interface was configured with address 10.96.0.1/11. Which commands could be used to configure RIP version 1 on this router to advertise both networks to neighboring routers? (Choose two.)

A. Router(config)# router rip
Router(config-router)# network 10.0.0.0 255.224.0.0

B. Router(config)# router rip
Router(config-router)# network 10.64.0.1 255.224.0.0
Router(config-router)# network 10.96.0.1 255.224.0.0

C. Router(config)# router rip
Router(config-router)# network 10.0.0.0

D. Router(config)# router rip
Router(config-router)# network 10.64.0.0
Router(config-router)# network 10.96.0.0

Answer: CD

Question 3:
It has become necessary to configure an existing serial interface to accept a second Frame Relay virtual circuit. Which of the following procedures are required to accomplish this task? (Choose three.)
A. Remove the IP address from the physical interface.
B. Encapsulate the physical interface with multipoint PPP.
C. Create the virtual interfaces with the interface command.
D. Configure each subinterface with its own IP address.
E. Disable split horizon to prevent routing loops between the subinterface networks.
F. Configure static Frame Relay map entries for each subinterface network.

Answer: ACD

Question 4:

Refer to the displayed graphic. RtrB and RtrC are configured for RIPv1 and have complete connectivity. RtrA is added to the network. What is the most appropriate RtrA configuration for full connectivity?

A. RtrA(config)# router rip
RtrA(config-router)# network 10.0.0.0
RtrA(config-router)# network 172.16.0.0
RtrA(config-router)# network 192.168.1.0

B. RtrA(config)# router rip
RtrA(config-router)# network 10.0.0.0

C. RtrA(config)# router rip
RtrA(config-router)# network 10.0.0.0
RtrA(config-router)# network 172.16.0.0

D. RtrA(config)# router rip
RtrA(config-router)# network 10.0.0.0
RtrA(config-router)# network 192.168.1.0

Answer: C

Explanation:
RtrA router need to be configured to advertise its connected networks into RIPv1.
It has two networks 172.16.1.0 /24 and 10.1.1.0 /24, since we are using RIPv1 the classfull network address of both Class A and Class B are used to advertise these networks on RtrA.

Question 5:
Which of the following are true regarding the command output shown in the display? (Choose two.)
A. There are at least two routers participating in the RIP process.
B. A ping to 192.168.168.2 will be successful.
C. A ping to 10.0.15.2 will be successful.
D. RtrA has three interfaces participating in the RIP process.

Answer: AC

Question 6:
Which of the following are true regarding the debug output shown in the graphic? (Choose two.)

A. This router was configured with the commands:
RtrA(config)# router rip
RtrA(config-router)# network 172.16.0.0
RtrA(config-router)# network 10.0.0.0

B. This router was configured with the commands:
RtrA(config)# router rip
RtrA(config-router)# network 192.168.1.0
RtrA(config-router)# network 10.0.0.0
RtrA(config-router)# network 192.168.168.0

C. This router was configured with the commands:
RtrA(config)# router rip
RtrA(config-router)# version 2
RtrA(config-router)# network 172.16.0.0
RtrA(config-router)# network 10.0.0.0

D. Split horizon was disabled on this router.
E. Network 192.168.168.0 will be displayed in the routing table.
F. Network 10.0.0.0 will be displayed in the routing table.

Answer: AF

Question 7:
When a router is connected to a Frame Relay WAN link using a serial DTE interface, how is the interface clock rate determined?
A. It is supplied by the CSU/DSU.
B. It is supplied by the far end router.
C. It is determined by the clock rate command.
D. It is supplied by the Layer 1 bit stream timing.

Answer: A

Question 8:
On point-to-point networks, OSPF hello packets are addressed to which address?
A. 127.0.0.1
B. 172.16.0.1
C. 192.168.0.5
D. 223.0.0.1
E. 224.0.0.5
F. 254.255.255.255

Answer: E

Question 9:
Which of the following statements describe the network shown in the graphic? (Choose two.)

A. There are two broadcast domains in the network.
B. There are four broadcast domains in the network.
C. There are six broadcast domains in the network.
D. There are four collision domains in the network.
E. There are five collision domains in the network.
F. There are seven collision domains in the network.

Answer: AF

Question 10:
Refer to the graphic. Host A is communicating with the server. What will be the destination MAC address of the frames sent by Host A to the server?

A. the MAC address of router interface e0
B. the MAC address of router interface e1
C. the MAC address of the server network interface
D. the MAC address of the network interface of Host A

Answer: A

Question 11:
Which destination addresses will be used by Host A to send data to Host C? (Choose two.) A. the IP address of Switch 1
B. the MAC address of Switch 1
C. the IP address of Host C
D. the MAC address of Host C
E. the IP address of the router's E0 interface
F. the MAC address of the router's E0 interface

Answer: CF

Question 12:
To configure the VLAN trunking protocol to communicate VLAN information between two switches, what two requirements must be met? (Choose two.)
A. Each end of the trunk line must be set to IEEE 802.1E encapsulation.
B. The VTP management domain name of both switches must be set the same.
C. All ports on both the switches must be set as access ports.
D. One of the two switches must be configured as a VTP server.
E. A rollover cable is required to connect the two switches together.
F. A router must be used to forward VTP traffic between VLANs.

Answer: BD

Question 13:
Which of the following commands will configure a default route to any destination network not found in the routing table?
A. Router(config)# ip default-route 0.0.0.0 255.255.255.255 s0
B. Router(config)# ip route 0.0.0.0 255.255.255.255 s0
C. Router(config)# ip default-route 0.0.0.0 s0
D. Router(config)# ip route 0.0.0.0 0.0.0.0 s0
E. Router(config)# ip route any any e0

Answer: D

Question 14:
Refer to the output of the corporate router routing table shown in the graphic. The corporate router receives an IP packet with a source IP address of 192.168.214.20 and a destination address of 192.168.22.3. What will the router do with this packet?

A. It will encapsulate the packet as Frame Relay and forward it out interface Serial 0/0.117.
B. It will discard the packet and send an ICMP Destination Unreachable message out interface FastEthernet 0/0.
C. It will forward the packet out interface Serial 0/1 and send an ICMP Echo Reply message out interface serial
0/0.102.
D. It will change the IP packet to an ARP frame and forward it out FastEthernet 0/0.

Answer: B

Question 15:
What is the default administrative distance of the OSPF routing protocol?
A. 90
B. 100
C. 110
D. 120
E. 130
F. 170

Answer: C

Question 16:
Refer to the diagram. All hosts have connectivity with one another. Which statements describe the addressing scheme that is in use in the network? (Choose three.)
A. The subnet mask in use is 255.255.255.192.
B. The subnet mask in use is 255.255.255.128.
C. The IP address 172.16.1.25 can be assigned to hosts in VLAN1
D. The IP address 172.16.1.205 can be assigned to hosts in VLAN1
E. The LAN interface of the router is configured with one IP address.
F. The LAN interface of the router is configured with multiple IP addresses.

Answer: BCF

Question 17:
How many broadcast domains are shown in the graphic assuming only the default VLAN is configured on the switches?

A one
B. two
C. six
D. twelve

Answer: A

Question 18:
The access list shown in the graphic should deny all hosts located on network 172.16.1.0, except host 172.16.1.5, from accessing the 172.16.4.0 network. All other networks should be accessible. Which command sequence will correctly apply this access list?
A. routerA(config)# interface fa0/0
routerA(config-if)# ip access-group 10 in
B. routerA(config)# interface s0/0
routerA(config-if)# ip access-group 10 out
C. routerB(config)# interface fa0/1
routerB(config-if)# ip access-group 10 out
D. routerB(config)# interface fa0/0
routerB(config-if)# ip access-group 10 out
E. routerB(config)# interface s0/1
routerB(config-if)# ip access-group 10 out

Answer: D

Question 19:
The show interfaces serial 0/0 command resulted in the output shown in the graphic. What are possible causes for this interface status? (Choose three.)

A. The interface is shut down.
B. No keepalive messages are received.
C. The clockrate is not set.
D. No loopback address is set.
E. No cable is attached to the interface.
F. There is a mismatch in the encapsulation type.

Answer: BCF

Question 20:
Which statement is correct about the internetwork shown in the diagram?
A. Switch 2 is the root bridge.
B. Spanning Tree is not running.
C. Host D and Server 1 are in the same network.
D. No collisions can occur in traffic between Host B and Host C.
E. If Fa0/0 is down on Router 1, Host A cannot access Server 1.
F. If Fa0/1 is down on Switch 3, Host C cannot access Server 2.

Answer: E

CCNA Exam Topic : Planning & Designing 2

2007-05-07T07:26:00.001-07:00

Continue .. Planning & Designing CCNA actual exam questions.

Question 21:
A network administrator issues the ping 192.168.2.5 command and successfully tests connectivity to a host that has been newly connected to the network. Which protocols were used during the test? (Choose two.)

A. ARP
B. CDP
C. DHCP
D. DNS
E. ICMP

Answer: AE

Question 22:
How does replacing a hub with a switch affect CSMA/CD behavior in an Ethernet network?
A. It effectively eliminates collisions.
B. In increases the size of the collision domain by allowing more devices to be connected at once.
C. It decreases the amount of time that a jam signal must be sent to reach all network devices.
D. It reduces the total amount of bandwidth available to each device.
E. It eliminates Layer 3 broadcast traffic.

Answer: A

Question 23:
A mid-sized company with five branch offices across Canada wants to create a WAN that will provide the most cost effective fully meshed environment with at least 512 kbps throughput. What WAN service would meet
this need?
A. Frame Relay
B. leased lines
C. ISDN BRI
D. ATM
E. PPP

Answer: A

Question 24:
Which statement about the ip classless router command is true?
A. The ip classless command is enabled by default in recent versions of IOS.
B. The ip classless command should only be enabled when static routing is being used instead of a routing protocol.
C. The ip classless command should be enabled by the network administrator whenever RIPv1 or IGRP is being used.
D. The ip classless command should be enabled by the network administrator whenever OSPF, RIPv2, or EIGRP is being used.

Answer: A

Question 25:
Refer to the exhibit. A new subnet with 60 hosts has been added to the network. Which subnet address should this network use to provide enough usable addresses while wasting the fewest addresses?
A. 192.168.1.56/26
B. 192.168.1.56/27
C. 192.168.1.64/26
D. 192.168.1.64/27

Answer: C

Explanation:
A subnet with 60 host is 2*2*2*2*2*2 = 64 -2 == 62
6 bits needed for hosts part. Therefore subnet bits are 2 bits (8-6) in fourth octet.
8bits+ 8bits+ 8bits + 2bits = /26
/26 bits subnet is 24bits + 11000000 = 24bits + 192
256 – 192 = 64
0 -63
64 – 127

Question 26:
The system LED is amber on a Cisco Catalyst 2950 series switch. What does this indicate?
A. The system is malfunctioning.
B. The system is not powered up.
C. The system is powered up and operational.
D. The system is forwarding traffic.
E. The system is sensing excessive collisions.

Answer: A

Question 27:
Which two subnetworks would be included in the summarized address of 172.31.80.0 /20? (Choose two.)
A. 172.31.17.4 /30
B. 172.31.51.16 /30
C. 172.31.64.0 /18
D. 172.31.80.0 /22
E. 172.31.92.0 /22
F. 172.31.192.0 /18

Answer: DE

Question 28:
What is CSMA/CD?
A. It is a deterministic mechanism that allows the orderly transmission of frames.
B. It is a way that priority is determined for data transmission based on MAC address.
C. It is a set of rules that determines path selection in an Ethernet network.
D. It is a set of rules that allows the best-effort transmission of frames in a LAN environment.

Answer: D

Question 29:
Why will a switch never learn a broadcast address?
A. Broadcasts only use network layer addressing.
B. A broadcast frame is never forwarded by a switch.
C. A broadcast address will never be the source address of a frame.
D. Broadcast addresses use an incorrect format for the switching table.
E. Broadcast frames are never sent to switches.

Answer: C

Question 30:
A network administrator is explaining VTP configuration to a new technician. What should the network administrator tell the new technician about VTP configuration? (Choose three.)
A. A switch in the VTP client mode cannot update its local VLAN database.
B. A trunk link must be configured between the switches to forward VTP updates.
C. A switch in the VTP server mode can update a switch in the VTP transparent mode.
D. A switch in the VTP transparent mode will forward updates that it receives to other switches.
E. A switch in the VTP server mode only updates switches in the VTP client mode that have a higher VTP revision number.
F. A switch in the VTP server mode will update switches in the VTP client mode regardless of the configured VTP domain membership.

Answer: ABD

Question 31:
What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?
A. It creates a VLAN 999 interface.
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.

Answer: B

Question 32:
A network administrator is designing a new corporate internetwork. The corporation is concerned about downtime due to link failure and also about link costs. Which topology will provide some redundancy to increase reliability for all sites but will cost less than a fully redundant topology?
Answer: B

Question 33:
A network administrator is designing a new corporate internetwork. The corporation is most concerned about downtime due to link failure and is willing to incur higher carrier costs to provide the needed reliability. Which topology will provide the maximum amount of reliability?
Answer: C

Question 34:
A network administrator is designing a new corporate internetwork. The corporation is concerned about link costs but wants to provide the branch offices with direct connectivity to headquarters. Which topology will provide each branch office with a direct connection to headquarters while minimizing connectivity costs?
Answer: D

CCNA Exam Topic : Planning & Designing

2007-04-23T07:33:00.000-07:00

CCNA Planning & Designing topic explains all the actual and real questions that would be on ccna test.

Question 1:
Which of the following host addresses are members of networks that can be routed across the public Internet?(Choose three.)
A. 10.172.13.65
B. 172.16.223.125
C. 172.64.12.29
D. 192.168.23.252
E. 198.234.12.95
F. 212.193.48.254

Answer: CEF

Explanation:
Private IP address scheme
Class A: 10.0.0.0 – 10.255.255.255
Class B: 172.16.0.0 – 172.31.255.255
Class C: 192.168.0.0 – 192.168.255.255
Other then private ip addresses remaining IP’s addresses are routed across internet.

Question 2:
Given a subnet mask of 255.255.255.224, which of the following addresses can be assigned to network hosts?
(Choose three.)
A. 15.234.118.63
B. 92.11.178.93
C. 134.178.18.56
D. 192.168.16.87
E. 201.45.116.159
F. 217.63.12.192

Answer: BCD

Explanation:
For calculating network hosts range for subnet 255.255.255.224
Simple method to find out network subnet is 256 -224 = 32
Write down the multiples of 32 to get subnet networks
Host range for subnet 255.255.255.224 are between this ranges below
0 ----- 31 (0 is network address and 31 is broadcast address)
32 -----63
64 -----95
96 -----127
128 ----159
160---- 191
192 ----223
224 ----255

Question 3:
When variable length subnet masking is used, what does the term route aggregation describe?
A. calculating the total number of available host addresses in the AS
B. combining routes to multiple networks into one supernet
C. reducing the number of unusable addresses by creating many subnets from one supernet
D. reclaiming unused address space by changing the subnet size

Answer: B

Explanation:
Route aggregration is an effort to route smaller prefixes via an aggregated larger prefix (supernetting). The advantage is obvious: Many /24 networks, for example, could be aggregated to larger networks like /23, /22 or even bigger prefixes.

Question 4:
ABC Company is merging with several local businesses that use routers from multiple vendors. Which routing protocol would work best to connect ABC Company with the enterprise networks it has acquired by providing scalability and VLSM support while minimizing network overhead?

A. RIP v1
B. RIP v2
C. IGRP
D. OSPF
E. EIGRP

Answer: D

Explanation:
Since only OSPF,EIGRP and RIPv2 supports VLSM in above options. It requires working with multi vendor and providing scalability OSPF is best choice of the three mentioned.

Question 5:
Which of the following IP addresses fall into the CIDR block of 115.64.4.0/22? (Choose three.)
A. 115.64.8.32
B. 115.64.7.64
C. 115.64.6.255
D. 115.64.3.255
E. 115.64.5.128
F. 115.64.12.128

Answer: BCE

Explanation:
/22 is 8bits + 8bits + 6bits i.e 11111111.11111111.11111100.0
Third octet 11111100 = 128+64+32+16+8+4
= 252 therefore subnet mask is 255.255.252.0
Subnet networks are 256-252= 4
Host range for above subnet are
0------- 3
4 ------ 7

Host that fall under 115.64.4.0 /22 networks are
4 5 6 7

Question 6:
In the implementation of VLSM techniques on a network using a single Class C IP address, which subnet mask is the most efficient for point-to-point serial links?
A. 255.255.255.0
B. 255.255.255.240
C. 255.255.255.248
D. 255.255.255.252
E. 255.255.255.254

Answer: D

Explanation:
For point-to-point serial link exist only two hosts so the best possible subnet mask for two useable hosts for class C network is 255.255.255.252

Question 7:
Which statements are true regarding classless routing protocols? (Choose two.)
A. The use of discontiguous subnets is not allowed.
B. The use of variable length subnet masks is permitted.
C. RIP v1 is a classless routing protocol.
D. IGRP supports classless routing within the same autonomous system.
E. RIP v2 supports classless routing.

Answer: BE

Question 8:

The company internetwork is subnetted using 29 bits. Which wildcard mask should be used to configure an extended access list to permit or deny access to an entire subnetwork?
A. 255.255.255.224
B. 255.255.255.248
C. 0.0.0.224
D. 0.0.0.8
E. 0.0.0.7
F. 0.0.0.3

Answer: E

Explanation:
29 bits subnet is 8bits + 8bits + 8bits + 5bits
255.255.255.(5bits)
11111000 = 128+64+32+16+8+0+0+0
= 248
Subnet is 255.255.255.248
Simple method to calculate the Wildcard mask from known subnet is to
Reverse 1’s into 0’s and 0’s into 1’s from the binary representation of subnet.
For above example (248 = 11111000 subnet)
11111000 (subnet) = 00000111 (wildcard mask) last octet.
= 7 (wildcard mask) for last octet.
Converting the remaining first 3 octets of subnet into wildcard mask using above method
Resulted wildcard mask is 0.0.0.7

Question 9:
The MDA Company is implementing dialup services to enable remote office employees to connect to the local network. The company uses several different Layer 3 protocols on the network. Authentication of the users connecting to the network is required for security. Additionally, some employees will be dialing long distance and will need callback support. Which protocol is the best choice for these remote access services?
A. 802.1
B. Frame relay
C. HDLC
D. PPP
E. SLIP
F. PAP

Answer: D

Question 10:
Refer to the diagram. All hosts have connectivity with one another. Which statements describe the addressing scheme that is in use in the network? (Choose three.)

A. The subnet mask in use is 255.255.255.192.
B. The subnet mask in use is 255.255.255.128.
C. The IP address 172.16.1.25 can be assigned to hosts in VLAN1
D. The IP address 172.16.1.205 can be assigned to hosts in VLAN1
E. The LAN interface of the router is configured with one IP address.
F. The LAN interface of the router is configured with multiple IP addresses.

Answer: BCF

Question 11:
Which routing protocols will support the following IP addressing scheme? (Choose three.)
A. RIP version 1
B. RIP version 2
C. IGRP
D. EIGRP
E. OSPF

Answer: BDE

Question 12:
A company with 25 computers decides to connect its network to the Internet. The company would like for all of the computers to have access to the Internet at the same time, but the company only has four usable public IP addresses. What should be configured on the router so that all computers can connect to the Internet simultaneously?
A. static NAT
B. global NAT
C. dynamic NAT
D. static NAT with ACL’s
E. dynamic NAT with overload

Answer: E

Question 13:
A network administrator would like to implement NAT in the network shown in the graphic to allow inside hosts to use a private addressing scheme. Where should NAT be configured?

A. Corporate router
B. Engineering router
C. Sales router
D. all routers
E. all routers and switches

Answer: A

Question 14:
Which of the following describe private IP addresses? (Choose two.)
A. addresses chosen by a company to communicate with the Internet
B. addresses that cannot be routed through the public Internet
C. addresses that can be routed through the public Internet
D. a scheme to conserve public addresses
E. addresses licensed to enterprises or ISPs by an Internet registry organization

Answer: BD

Question 15:
Refer to the graphic. A host is connected to switch port Fa0/3 with a crossover cable. The host and switch have been fully configured for IP connectivity as shown. However, the port indicator on switch port Fa0/3 is not on, and the host can not communicate with any other hosts including those connected to VLAN 2 on the same switch. Based on the information given, what is the problem?
A. Switch port Fa0/3 is not configured as a trunk port.
B. The cable is the wrong type.
C. The switch has been assigned an incorrect subnet mask.
D. Switch port Fa0/3 has been blocked by STP.
E. The switch and the hosts must be in the same subnet.

Answer: B

Explanation:
Straight through cable is used to connect a host to switch.

Question 16:
What kind of cable should be used to establish a trunked link between two Catalyst 2950 switches?
A. a straight-through cable
B. an EIA/TIA-232 serial cable
C. an auxiliary cable
D. a modem cable
E. a cross-over cable

Answer: E

Explanation:
Cross-over cable is used to connect two switches.

Question 17:
What is the purpose of Spanning Tree Protocol?
A. to prevent routing loops
B. to create a default route
C. to provide multiple gateways for hosts
D. to maintain a loop-free Layer 2 network topology
E. to enhance the functions of SNMP

Answer: D

Question 18:
The network 172.25.0.0 has been divided into eight equal subnets. Which of the following IP addresses can be assigned to hosts in the third subnet if the ip subnet-zero command is configured on the router? (Choose three.)
A. 172.25.78.243
B. 172.25.98.16
C. 172.25.72.0
D. 172.25.94.255
E. 172.25.96.17
F. 172.25.100.16

Answer: ACD

Question 19:
Which wild card mask will enable a network administrator to permit access to the Internet for only hosts that are assigned an address in the range of 192.168.8.0 through 192.168.15.255?
A. 0.0.0.0
B. 0.0.0.255
C. 0.0.255.255
D. 0.0.7.255
E. 0.0.3.255

Answer: D

Question 20:
The exhibit shows a company network. The network administrator would like to permit only hosts on the 172.30.16.0/24 network to access the Internet. Which wild card mask and address combination will only match addresses on this network? A. 172.30.0.0 0.0.0.0
B. 172.30.16.0 0.0.0.255
C. 172.30.0.0 0.0.15.255
D. 172.30.16.0 0.0.31.255
E. 172.30.16.0 0.0.255.255

Answer: B

CCNA Exam Topic : Troubleshooting 2

2007-04-17T10:06:00.000-07:00

cisa CCDA CCNA CCNP CCDP MCP MCSE MCSE MCSE
Continue of Troubleshooting CCNA actual exam questions.

Question 17:
Refer to the exhibit. All switch ports are assigned to the correct VLANs, but none of the hosts connected to SwitchA can communicate with hosts in the same VLAN connected to SwitchB. Based on the output shown, what is the most likely problem?

A. The access link needs to be configured in multiple VLANs.
B. The link between the switches is configured in the wrong VLAN.
C. The link between the switches needs to be configured as a trunk.
D. VTP is not configured to carry VLAN information between the switches.
E. Switch IP addresses must be configured in order for traffic to be forwarded between the switches.

Answer: C

Explanation:
For VLAN information to travel from one switch to another within the same VLAN we need to configure the link port between switches as trunk ports.
Switchport mode trunk

Question 18:
Refer to the exhibit. The network administrator normally establishes a Telnet session with the switch from host A. However, host A is unavailable. The administrator's attempt to telnet to the switch from host B fails, but pings to the other two hosts are successful. What is the issue?
A. Host B and the switch need to be in the same subnet.
B. The switch interface connected to the router is down.
C. Host B needs to be assigned an IP address in VLAN 1.
D. The switch needs an appropriate default gateway assigned.
E. The switch interfaces need the appropriate IP addresses assigned.

Answer: D

Explanation:
Ping was successful form host B to other hosts because of intervlan routing configured on router. But to manage switch via telnet the VLAN32 on the switch needs to be configured interface vlan32 along with ip address and its appropriate default-gateway address.
Since VLAN1 interface is already configure on switch Host A was able to telnet switch.

Question 19:
Refer to the exhibit. Configuration of both switches has been completed. During testing, the network administrator notices that users on SwitchA can not connect with users in the same VLAN on SwitchB. What should be done to solve this problem?

A. Ensure that the IP address of SwitchA is on the same network as the IP address of SwitchB.
B. Ensure that the same interface number is used to connect both switches.
C. Ensure that the ports connecting the two switches are configured to trunk.
D. Ensure that SwitchA and SwitchB are connected with a straight-through cable.

Answer: C

Explanation:
For VLAN information to communicate from one switch to another within the same VLAN we need to configure the link port (Fa0/3 switchA and fa0/4 switchB) between switches as trunk ports.

Switchport mode trunk

Question 20:
Refer to the exhibit. The switches have been configured with static VLANs as shown. During testing, the network administrator notices that VLAN 20 on SwitchA has no connectivity with VLAN 30 on SwitchB. What should the network administrator do?

A. Configure the interconnected ports on SwitchA and SwitchB into access mode.
B. Connect the two switches with a straight-through cable.
C. Add a Layer 3 device to connect VLAN 20 and VLAN 30.
D. Configure the management VLAN with IP addresses.
E. Ensure that the VTP passwords match on both switches.

Answer: C

Explanation:
To enable connectivity between two different VLAN we need to add a layer 3 device and configure interVLAN routing on it.

Question 21:
Refer to the exhibit. The two connected ports on the switch are not turning orange or green. What would be the most effective steps to troubleshoot this physical layer problem? (Choose three.)

A. Ensure that the Ethernet encapsulations match on the interconnected router and switch ports.
B. Ensure that cables A and B are straight-through cables.
C. Ensure cable A is plugged into a trunk port.
D. Ensure the switch has power.
E. Reboot all of the devices.
F. Reseat all cables.

Answer: BDF

Explanation:

Question 22:
Refer to the exhibit. A network administrator needs to add a new VLAN, named VLAN3, to the network shown. Unfortunately, there is not another FastEthernet interface on R1 to connect to the new VLAN3. Which approach is the most cost effective solution for this problem?
A. Purchase a new FastEthernet module and install it on R1.
B. Replace R1 with a new router that has at least three FastEthernet interfaces.
C. Configure a second switch to support VLAN3 with a VLAN trunk between SW1 and the new switch.
D. Configure a single VLAN trunk between R1 and SW1 and configure a subinterface on the R1 interface for
each VLAN.
E. Connect another router to a serial interface of R1. Use a FastEthernet interface on the new router for VLAN3..

Answer: D

Explanation:
Create sub interfaces on R1 for each VLAN this way we can save physical ports and be more cost effective , make the port connecting the R1 from switch has trunk port to carry all VLAN information.

Question 23:
Refer to the exhibit. S0/0 on R1 is configured as a multipoint interface to communicate with R2 and R3 in this hub-and-spoke Frame Relay topology. While testing this configuration, a technician notes that pings are successful from hosts on the 172.16.1.0/24 network to hosts on both the 172.16.2.0/25 and 172.16.2.128/25 networks. However, pings between hosts on the 172.16.2.0/25 and 172.16.2.128/25 networks are not successful. What could explain this connectivity problem?
A. The ip subnet-zero command has been issued on the R1 router.
B. The RIP v2 dynamic routing protocol cannot be used across a Frame Relay network.
C. Split horizon is preventing R2 from learning about the R3 networks and R3 from learning about the R2 networks.
D. The 172.16.2.0/25 and 172.16.2.128/25 networks are overlapping networks that can be seen by R1, but not between R2 and R3.
E. The 172.16.3.0/29 network used on the Frame Relay links is creating a discontiguous network between the R2 and R3 router subnetworks.

Answer: C

Explanation:
Split horizon by default does not allow routing updates to go in and out of the same interface.

Question 24:
While troubleshooting a connectivity problem, a network administrator notices that a port status LED on a Cisco Catalyst series switch is alternating green and amber. Which condition could this indicate?

A. The port is experiencing errors.
B. The port is administratively disabled.
C. The port is blocked by spanning tree.
D. The port has an active link with normal traffic activity.

Answer: A

Explanation:
Color Port Status
Off No link.
Solid green Link operational (with no link activity).
Flashing green Link operational (with activity). .
Alternating green and amber Link fault. Error frames can affect connectivity, and errors such as excessive collisions, CRC errors, and alignment and jabber errors are monitored for a link-fault indication.
Solid amber Port is not forwarding. For example, this could be because the port was disabled by management, suspended due to an address violation, or suspended by Spanning-Tree Protocol due to the presence of network loops.

Question 25:
Refer to the exhibit. Users on WS1 and WS2 are unable to reach the SR1 and SR2 servers to gain the files needed. A ping from the workstations WS1 and WS2 to the gateway address 192.168.2.1 is successful. Which IOS command should the IT administrator issue on RTA to troubleshoot the problem?

A. show ip route
B. configure terminal
C. show startup-config
D. show ip interface FastEthernet0/0

Answer: A

Explanation:
show ip route command displays the routing table which provides the information about networks the router has routes.

Question 26:
Refer to the exhibit. HostA cannot ping HostB. Assuming routing is properly configured, what could be the cause of this problem?A. HostA is not on the same subnet as its default gateway.
B. The address of SwitchA is a subnet address.
C. The Fa0/0 interface on RouterA is on a subnet that can't be used.
D. The serial interfaces of the routers are not on the same subnet.
E. The Fa0/0 interface on RouterB is using a broadcast address.

Answer: D

Explanation:
For IP address 192.168.1.62 /27 host range are 192.168.1.32 -192.168.1.63
And for IP address 192.168.1.65 /27 host range are 192.168.1.64 – 192.168.1.95 Because both serial interfaces IPs are configured for different subnet the routing is not possible between both routers.

Question 27:
The system LED is amber on a Cisco Catalyst 2950 series switch. What does this indicate?
A. The system is malfunctioning.
B. The system is not powered up.
C. The system is powered up and operational.
D. The system is forwarding traffic.
E. The system is sensing excessive collisions.

Answer: A

Explanation:

See question number 24.

Question 28:
Refer to the exhibit. Serial0/0 does not respond to a ping request from a host on the FastEthernet0/0 LAN.How can this problem be corrected?

A. Enable the Serial 0/0 interface.
B. Correct the IP address for Serial 0/0.
C. Correct the IP address for FastEthernet 0/0.
D. Change the encapsulation type on Serial 0/0.
E. Enable autoconfiguration on the Serial 0/0 interface.

Answer: A

Explanation:
Need to run the command no shutdown to enable the serial 0/0 from administratively down to up state.

Question 29:

Refer to the exhibit. Connectivity cannot be made to the Internet. As part of the troubleshooting process, the user issued the ipconfig command, which generated the output shown in the exhibit. What step should the user take next in the troubleshooting process?

C:\Documents and Settings\host>ipconfig
Windows IP Configuration
Ethernet adapter Local Area Connection

IP Address. . . . . . . . . . . . : 192.168.1.3

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 192.168.1.1
C:\Documents and Settings\host>ping 192.168.1.1
Pinging 192.168.1.1 with 32 bytes of data:

Request timeout, Request timeout, request timeout.

A. Replace the NIC.
B. Reload the NIC driver.
C. Check the IP host address.
D. Check the default gateway address.
E. Check connectivity to the DNS server.

Answer: D

Explanation:

Verify the default-gateway address and check is it powered ON.

Question 30:
Refer to the exhibit. The Bigtime router is unable to authenticate to the Littletime router. What is the cause of the problem?
A. The usernames are incorrectly configured on the two routers.
B. The passwords do not match on the two routers.
C. CHAP authentication cannot be used on a serial interface.
D. The routers cannot be connected from interface S0/0 to interface S0/0.
E. With CHAP authentication, one router must authenticate to another router. The routers cannot be configured to authenticate to each other.

Answer: B

Explanation:

Configure the usernames and passwords. To do so, issue the username username password password command, where username is the hostname of the peer (neighbor). Ensure that:
· Passwords are identical at both ends.
The router name and password are exactly the same, because they are case-sensitive.

Question 31:
Refer to the exhibit. A technician is testing connection problems in the internetwork. What is the problem indicated by the output from HostA?

A. The routing on Router2 is not functioning properly.
B. An access list is applied to an interface of Router3.
C. The Fa0/24 interface of Switch1 is down.
D. The gateway address of HostA is incorrect or not configured.

Answer: D

Please comment if you have any doubts on troubleshooting Questions ...

ccna,CCDA CCNA CCNP CCDP MCP MCSE MCSE MCSE CCDA CCNA CCNP CCDP MCP

CCNA Router Simulator Question - VTP SIM

2007-04-14T10:00:00.000-07:00

CCNA CISA CCNP MCSE CCNA CISA CCNP MCSE CCNA CISA CCNP MCSE
VTP SIM TESTLET IS ANOTHER SIM EXAM QUESTION

VTP SIM

Question:
This task requires you to use the CLI of Sw-AC3 to answer five multiple-choice questions. This does not require any configuration.
To answer the multiple-choice questions, click on the numbered boxes in the right panel.
There are five multiple-choice questions with this task. Be sure to answer all five questions before leaving this item.

Click on the exhibit for larger picture

Important: The VTP simlet has a pool of 10 question . Test may have only 5 Questions for VTP SIM

some very usefull commands to answer this simlet:

show cdp neighbor , show cdp neighbor detail , show interface trunk or switchport , show mac-address-table, show spanning-tree, show vlan , show vtp status , show run .

The pool of 10 questions are discussed here starting with the 4 questions in the above picture.

Question 1 :

What interface did Sw-AC3 associate with source MAC address 0010.5a0c.ffba ?

Answer:

Fa 0/8 (As per the picture above)

To find out the associate interface number for a given mac address on the switch use the show mac-address-table command and search for the mac address 0010.5a0c.ffba and its associated interface number.

Question 2 :

what ports on Sw-AC3 are operating has trunks (choose two)?

Answer:

Fa 0/9 and Fa 0/12 (As per the picture above)

To find out the ports operating has trunks on a switch

Use the show interface trunk command this will display all the trunk ports configured on switch.

(or)

Use the show interface switchport command and check the output of the command for operational mode : type trunk for each and every interface.

Question 3:

What kind of router is VLAN-R1 ?

Answer:

2611 ( as per picture above)

To know details of directly connected Neighbor, use the following command on the switch show cdp neighbors command, this output gives the following details about its neighbors

Device ID, Local Interface ,Holdtme, Capability, Platform, Port ID

To know what kind of router is VLAN-R1 we need to identify its platform details from above command output.

Question 4:

Which switch is the root bridge for VLAN 1 ?

Answer:

Sw-AC3 (As per the question above in picture)

Step1: Use the Show spanning-tree vlan 1 command this output provide the mac address of the root bridge.

Step2: now use the show mac-address-table command this output associates the mac address to a interface number.

Step3: use the command show cdp neighbors this output will give us the local interface associated with the hostname(Device ID).

Question 5 :

Out of which port on switch Sw-Ac3 would a frame containing an IP packet with destination address that is not on a local LAN be forwarded?

Answer:

To forward any packet with destination address other then the subnet network of the switch, the switch usually forwards this IP packets to the layer 3 device example router connected to it.

Step1: Find the default-gateway(Router or layer 3 device) configured on the switch.

use the Show run command to view the IP address used to configure default-gateway on the switch.

Step2: Look for the router VLAN-R1 after using the show cdp neighbor detail command

Sample output of show cdp neighbor detail command for better understanding the output details

Device ID: C2950-1
Entry address(es):
Platform: Cisco WS-C2950T-24, Capabilities: Switch IGMP
Interface: FastEthernet0/0, Port ID (outgoing port): FastEthernet0/15
Holdtime : 139 sec

Two things to notice from above output

Interface: FastEthernet0/0 this statement provides that the neighbor(c2950-1) is connected to fa 0/0 on the c3660-2 local switch.

Port ID (outgoing port): FastEthernet0/15 this explains that neighbor (c2950-1) uses fa 0/15 port to reach c3660-2 switch.

FOR OUR QUESTION WE SHOULD LOOK FOR THE ROUTER VLAN-R1 corresponding details and to which port it is connected on local switch Sw-Ac3.

Step3: The port number to which the routerVLAN-R1 is connected on switch Sw-Ac3 is used to forward the packets with destination address that is not on a local LAN.

Question 6:

What address should be configured as the default-gateway for the host connected to interface fa 0/4 of SW-Ac3 ?

Answer:

Step1: Find the details of the VLAN assigned to interface fa 0/4 by using the show vlan command on Sw-Ac3.

The above exhibit question has fa 0/4 configured has VLAN1 based on the output from show vlan command.

Step2: From the exhibit question we know that VLAN1 is configured on router using sub-interface fa 0/0.1 with IP address 192.168.1.254 /24.

Step3: 192.168.1.254 should be configure as default-gateway address for the host connected to fa 0/4 on switch.

Because VLAN1 corresponds to fa 0/4 on Sw-Ac3 and host connected to fa 0/4 will be member of vlan1.

Question 7:

Out of which ports will frame with source mac-address 0015.5A0Cc.A086 and destination mac-address 000A.8A47.0612 be forwarded ?

Answer:

Step1: Use Show mac-address-table command on the switch.

The output of a show mac-address-table provides the mapping of mac address with port numbers. Search the output for the two mac-addresses provided in the question and select the destination mac address corresponding port number for correct answers.

Step2: If you do not find the above destination mac-address in SHOW MAC-ADDRESS-TABLE output , then the frame will be broadcast or flooded to all ports ( all ports may be ports of particular vlan on switch ,Selection of VLAN will be depending on the source mac-address port vlan membership) except the port it recieved from.

Question 8:

From which switch did Sw-Ac3 receive VLAN information ?

Answer:

Step1: Use Sw-Ac3#show vtp status command .

Sample output of show vtp status command

switch# show vtp status
VTP Version : 2
Configuration Revision : 255
Maximum VLANs supported locally : 1005
Number of existing VLANs : 35
VTP Operating Mode : Server
VTP Domain Name : Lab_Network
VTP Pruning Mode : Enabled
VTP V2 Mode : Enabled
VTP Traps Generation : Disabled
MD5 digest : 0x08 0x7E 0x54 0xE2 0x5A 0x79 0xA9 0x2D
Configuration last modified by 127.0.0.12 at 8-7-02 11:21:43
Local updater ID is 127.0.0.12 on interface EO0/0 (first interface found)

The local updater ID in the above output identifies the ip address of the device which is providing the VLAN information. The address could also be of the switch itself.

Step 2: Show cdp neighbor detail provides the hostname for corresponding to that IP address.

Question 9:

Refer to the exhibit. SwX was taken out of the production network for maintenance. It will be reconnected to the Fa 0/16 port of Sw-Ac3. What happens to the network when it is reconnected and a trunk exists between the two switches?

Answer:

Step1: On switch Sw-Ac3 use show vtp status command. Notice the output for domain name, Both switches must have same domain name configured to exchange vtp messages (exhibit domain name: home-office ).

Step2: If domain name matches, Then note Configuration Revision number of the Sw-Ac3 and compare it with the SwX , Whichever switch has highest configuration revision number will become the vtp updater. The switch which becomes vtp updater will replace other switch vlan information with its own vlan information.

Example if SwX revision number is highest , Then VLAN information that is configured in Sw-Ac3 will be replaced by the VLAN information in the SwX.

{ If you have any doubts or questions please comment here }

CCNA Router Simulator Question - ACL SIM

2007-04-13T08:09:00.000-07:00

CCNA CISA CCNP CISP
CCNA EXAM HAVE TWO SIMULATORS.

ACL SIM

CCNA CISA CCNP CISP
Answer:

Select the console on Corp1 router

Configuring ACL

Corp1>enable
Corp1#configure terminal

comment: To permit only Host C (192.168.33.3){source addr} to access finance server address (172.22.242.23) {destination addr} on port number 80 (web)
Corp1(config)#access-list 100 permit tcp host 192.168.33.3 host 172.22.242.23 eq 80

comment: To deny any source to access finance server address (172.22.242.23) {destination addr} on port number 80 (web)
Corp1(config)#access-list 100 deny tcp any host 172.22.242.23 eq 80

comment: To permit ip protocol from any source to access any destination because of the implicit deny any any statement at the end of ACL.
Corp1(config)#access-list 100 permit ip any any

Applying the ACL on the Interface

comment: Check show ip interface brief command to identify the interface type and number by checking the IP address configured.

Corp1(config)#interface fa 0/1

If the ip address configured already is incorrect as well as the subnet mask. this should be corrected in order ACL to work

type this commands at interface mode :

no ip address 192.x.x.x 255.x.x.x (removes incorrect configured ip address and subnet mask)

Configure Correct IP Address and subnet mask :

ip address 172.22.242.30 255.255.255.240 ( range of address specified going to server is given as 172.22.242.17 - 172.22.242.30 )

comment: Place the ACL to check for packets going outside the interface towards the finance web server.
Corp1(config-if)#ip access-group 100 out

Corp1(config-if)#end

Important: To save your running config to startup before exit.
Corp1#copy running-config startup-config

Verifying the Configuration :

Step1: show ip interface brief command identifies the interface on which to apply access list .

Step2: Click on each host A,B,C & D . Host opens a web browser page , Select address box of the web browser and type the ip address of finance web server(172.22.242.23) to test whether it permits /deny access to the finance web Server .

Step 3: Only Host C (192.168.33.3) has access to the server . If the other host can also access then maybe something went wrong in your configuration . check whether you configured correctly and in order.

Step 4: If only Host C (192.168.33.3) can access the Finance Web Server you can click on NEXT button to successfully submit the ACL SIM.

Any Questions on SIMULATOR welcomed.

Best of LUCK to your CCNA EXAM

CCNA CISA CCNP CISP

About Testinside CCNA Exam

2007-04-12T08:59:00.000-07:00

THIS TESTINSIDE BLOG IS FOR ALL THOSE ASPIRANTS WHO WISH TO BE A CCNA CERTIFIED..

Testinside is only for CCNA knowledge needed to pass.

Here you find explanation for CCNA exam questions.

To discuss and understand the concept of CCNA questions.

This also helps you if you had already learned the CCNA concepts and wish to test yourself before atempting the actual CCNA exam.

BROWSE THE ARCHIVE SECTION ON THIS BLOG FOR QUESTIONS AND ANSWERS BASED ON CCNA TOPIC.

Router & switch simulator questions of CCNA exam are also explained in detail
Check : ACL SIM and VTP SIM (640-801 exam)

New SIM: NAT (640-802 exam)

CCNA Exam Topics : Troubleshooting , Drag & Drop, Planning and Designing

Note: Drag & Drop is still same for 640-802 exam.

{ Currently i am working on this blog , please visit again or check archive section }

wISH yOU Best oF LucK for ccna