Monday, March 2, 2009

CCNA 640-802 VLAN / VTP Practice Questions

1.

Brief: CCNA exam requires a good understanding of VLAN / VTP concepts, terminology, and implementation using Cisco switches. We have given a few multiple choice questions to gauge your preparedness (yourself) of the subject before taking the exam!

Q1: Match the trunking protocols with respective media:
1. Inter Switch Link A. FDDI
2. LANE B. Fast Ethernet
3. 802.10 C. ATM

Choose the correct choice.
A. 1-> C, 2->B, 3->A
B. 1->B, 2->C, 3->A
C. 1->B, 2->A, 3->C
D. 1->A, 2->B, 3->C




Ans:B
Explanation:
ISL, 802.1Q are the VLAN trunking protocols associated with Fast Ethernet. The VLAN trunking protocol defined by 802.10 is associated with FDDI. LANE (LAN Emulation) is associated with ATM.


2.
Q2: Your switched network is using Inter-Switch Link (ISL) as VLAN trunking protocol. Which following must be a part of ISL header field?
A. Source Port Number
B. VLAN-ID
C. Destination port number
D. Destination network number


Ans: B
Explanation:
Inter-Switch Link (ISL) is one of the VLAN trunking protocols used for switched VLAN networks. It uses frame tagging to identify the VLAN. ISL encapsulates the original Ethernet frame, and a VLAN-ID is inserted into the ISL header.
3.
Q3: You have configured your network to have 3 VLANs. How many broadcast domains do you have?
A. 1
B. 2
C. 3
D. 4


Ans.: C
Explanation: It is important to know the difference between a collision domain and a broadcast domain. When you use Hubs, all the nodes connected to the hub will be in the same collision domain. However, when you use switches and implement VLANs, each VLAN will be in a separate broadcast domain. The packet forwarding between VLANs is achieved through the use of routing.
4.
Q4: Your network has 100 nodes on a single broadcast domain. You have implemented VLANs and segmented the network to have 2 VLANs of 50 nodes each. The resulting broadcast traffic effectively:
A. Increases two fold
B. Remains same
C. Decreases by half
D. Increases 4 fold



Ans: C
Explanation: By implementing VLANs,
1. The effective broadcast traffic decreases, since VLANs do not forward the broadcast traffic from one VLAN to another.
2. The security can be improved by implementing a router (A layer 3 device) to route the packets among VLANs.
5.
Q5: Which of the following are valid VLAN Trunk Protocols over Fast Ethernet? [Select 2].
A. Inter-Switch Link
B. 802.10
C. LANE
D. 802.1Q



Ans: A, D
Expl.: Inter-Switch Link and 802.1Q are two VLAN Trunking Protocols used with Fast Ethernet, that Cisco supports. LANE is associated with ATM and 802.10 is associated with FDDI. Also, it is important to note that ISL, 802.1Q, and 802.10 use Frame Tagging to identify the VLANs.

6.
Q6: You have two switches with 24 ports each and configured the network to have only one VLAN. Do you need to implement the VTP between the switches?

A. YES
B. NO


Ans: B
Expl.: The primary function of VTP is to tag frames (with VLAN ID) as they traverse through the switch fabric. The switch fabric is assumed to have multiple VLANs. If there is only one VLAN, there is no need to tag a frame. Therefore, there is no need to implement VTP between the switches that have only one VLAN.

7.
Q7: Which of the following is not a valid VTP mode?
A. Server
B. Client
C. Transparent
D. Hybrid



Ans: D
Expl.: VTP is a Layer 2 messaging protocol. It carries configuration information throughout a single domain. VTP operates in one of three modes:
1. Server mode
2. Client mode
3. Transparent mode
VTP Servers can create, modify, or delete VLANs and other configuration parameters for the specified VLAN domain.
A VTP client can't create, change, or delete VLANs.
A VTP transparent mode is used when a switch is not required to participate in VTP, but only pass the information to other switches. Transparent switches don't work either as Server or clients.
Configurations made to a single switch, called VTP server, are propagated across the switch fabric under a single domain control. Other switches, configured as VTP clients, learn the configuration information from the server. It is important to know that, Cisco switches such as Catalyst 1900, acting as VTP servers save the VLAN configuration information in their Non volatile memory (NVRAM), whereas client keep the information only in running configuration.
8.
Q8: A switch up-dates its VLAN configuration based on which of the following information? Choose the most appropriate answer.
A. Time of arrival of VTP update packet
B. Configuration Revision number
C. Direction of Arrival
D. Port that it has learned
Ans.: B
Expl.: A VTP advertisement necessarily consists of "Configuration revision number". Every time a VTP server updates its VLAN information, it increments the configuration revision number by one count. VTP clients, use the revision number to enforce the VLAN configuration Update.
9.
Q9: You have configured VLANs in your switched network and now want to check whether you have configured properly. Which command do you use? Assume that you are in privileged EXEC mode. Select one.
A. sh v-lan
B. sh vlan vlan#
C. sh vlan#
D. sh v-lans v-lan#



Ans.: B
Expl.: You use show vlan or shor vlan vlan# command to see the configuration details of VLANs. The command "sh vlan" will display the configuration information for all VLANs, where as the command "sh vlan vlan#" shows only the configuration information pertaining to that vlan. For example, if you want to see the configuration information for vlan2, you give the command "sh vlan 2".
10.
Q10: You want to see whether the pruning is enabled in you network or not. Which command can you use to check this?
A. sh version
B. sh spantree
C. sh vtp
D. sh vlan



Ans.: C
Expl.: To verify any configuration change, "show vtp" privileged executive command can be used. This command displays, among other things, VTP domain name, VTP password if any, VTP pruning mode (enabled or disabled) and the IP address of the device that last modified the configuration.