Thursday, March 15, 2012

CCNA – VLAN Questions 2

Question 1
Which of the following are benefits of VLANs? (Choose three)
A. They increase the size of collision domains.
B. They allow logical grouping of users by function.
C. They can enhance network security.
D. They increase the size of broadcast domains while decreasing the number of collision domains.
E. They increase the number of broadcast domains while decreasing the size of the broadcast domains.
F. They simplify switch administration.

Answer: B C E
Explanation
When using VLAN the number and size of collision domains remain the same -> A is not correct.
VLANs allow to group users by function, not by location or geography -> B is correct.
VLANs help minimize the incorrect configuration of VLANs so it enhances the security of the network -> C is correct.
VLAN increases the size of broadcast domains but does not decrease the number of collision domains -> D is not correct.
VLANs increase the number of broadcast domains while decreasing the size of the broadcast domains which increase the utilization of the links. It is also a big advantage of VLAN -> E is correct.
VLANs are useful but they are more complex and need more administration -> F is not correct.

Question 2
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)
VLAN_address_scheme.jpg
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: B C F
Explantion
First we should notice that different VLANs must use different sub-networks. In this case Host A (172.16.1.126) and Host B (172.16.1.129) are in different VLANs and must use different sub-networks. Therefore the subnet mask in use here should be 255.255.255.128. In particular, it is 172.16.1.0/25 with 2 sub-networks:
+ Sub-network 1: 172.16.1.0 -> 172.16.1.127 (assigned to VLAN 1)
+ Sub-network 2: 172.16.1.128 -> 172.16.1.255 (assigned to VLAN 2)
-> B is correct.
The IP address 172.16.1.25, which is in the same sub-network with host A so it can be assigned to VLAN 1 -> C is correct.
To make different VLANs communicate with each other we can configure sub-interfaces (with a different IP address on each interface) on the LAN interface of the router -> F is correct.

Question 3
A network associate is trying to understand the operation of the FLD Corporation by studying the network in the exhibit. The associate knows that the server in VLAN 4 provides the necessary resources to support the user hosts in the other VLANs. The associate needs to determine which interfaces are access ports. Which interfaces are access ports? (Choose three)
VLAN_access_ports.jpg
A. Switch1 – Fa0/2
B. Switch1 – Fa0/9
C. Switch2 – Fa0/3
D. Switch2 – Fa0/4
E. Switch2 – Fa0/8
F. Router – Fa1/0

Answer: A C D
Explanation
Access ports are switch’s ports which are connected to hosts.

Question 4
What are three valid reasons to assign ports to VLANs on a switch? (Choose three)
A. to make VTP easier to implement
B. to isolate broadcast traffic
C. to increase the size of the collision domain
D. to allow more devices to connect to the network
E. to logically group hosts according to function
F. to increase network security

Answer: B E F

Question 5
Which statement is correct about the internetwork shown in the diagram?
VLAN_interrouting.jpg
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 Router1, Host A cannot access Server1.
F. If Fa0/1 is down on Switch3, Host C cannot access Server2.

Answer: E
Explanation
Switch 2 cannot be the root bridge because all ports of root bridges are designated ports. In the diagram switch 2 has one blocked port -> It is not the root bridge -> A is not correct.
Because Switch 2 has a blocked port so surely Spanning Tree Protocol is running -> B is not correct.
Host D belongs to VLAN 2 while Server 1 belongs to VLAN 3 so they are not in the same network  -> C is not correct.
Host B & host C are connected through a hub so they are in the same collision domain and collision can occur -> D is not correct.
We need a router to allow different VLANs to communicate with each other. This router is called “router on a stick”. In this case it is Router1. The link between Router1 and Switch1 is configured as trunk link. If this link is down, different VLANs cannot communicate with each other -> E is correct.
If Fa0/1 is down on Switch3, Spanning Treel Protocol will “open” the blocked port on Switch 2 can Host C can access Server 2 through HostC -> Hub1 -> Switch2 -> Switch1 -> Router1-> Switch1 -> Server2 (notice that it must go through Router1 because they are in different VLANs). So F is not correct.

Question 6
Refer to the exhibit. Which of these statements correctly describes the state of the switch once the boot process has been completed?
VLAN_VLAN1_down.jpg
A. As FastEthernet0/12 will be the last to come up, it will not be blocked by STP.
B. Remote access management of this switch will not be possible without configuration change.
C. More VLANs will need to be created for this switch.
D. The switch will need a different IOS code in order to support VLANs and STP.

Answer: B
Explanation
From the output we notice that the administrator has just shut down Interface Vlan1, which is the default VLAN so no one can access it remotely (like telnet) -> B is correct.
Answer A is not correct as STP calculation does not depend on which port comes up first or last. STP recalculates when there is a change in the network.
A normal switch can operate without VLAN -> C is not correct.
This IOS does support VLAN because it has VLAN 1 on it -> D is not correct.

CCNA – VLAN Questions

Question 1
Refer to the exhibit. A network associate needs to configure the switches and router in the graphic so that the hosts in VLAN3 and VLAN4 can communicate with the enterprise server in VLAN2. Which two Ethernet segments would need to be configured as trunk links? (Choose two)
VLAN_trunking.jpg
A. A
B. B
C. C
D. D
E. E
F. F

Answer: C F
Explanation
The link between the switches and the link between switch & router should be configured as trunks. Other links (connected to hosts) should be configured as access links.

Question 2
Which three statements are typical characteristics of VLAN arrangements? (Choose three)
A. A new switch has no VLANs configured.
B. Connectivity between VLANs requires a Layer 3 device.
C. VLANs typically decrease the number of collision domains.
D. Each VLAN uses a separate address space.
E. A switch maintains a separate bridging table for each VLAN.
F. VLANs cannot span multiple switches.

Answer: B D E
Explanation
By default, all ports on a new switch belong to VLAN 1 (default & native VLAN). There are also some well-known VLANs (for example: VLAN 1002 for fddi-default; VLAN 1003 for token-ring…) configured by default -> A is not correct.
To communicate between two different VLANs we need to use a Layer 3 device like router or Layer 3 switch -> B is correct.
VLANs don’t affect the number of collision domains, they are the same -> C is not correct. Typically, VLANs increase the number of broadcast domains.
We must use a different network (or sub-network) for each VLAN. For example we can use 192.168.1.0/24 for VLAN 1, 192.168.2.0/24 for VLAN 2 -> D is correct.
A switch maintains a separate bridging table for each VLAN so that it can send frame to ports on the same VLAN only. For example, if a PC in VLAN 2 sends a frame then the switch look-ups its bridging table and only sends frame out of its ports which belong to VLAN 2 (it also sends this frame on trunk ports) -> E is correct.
We can use multiple switches to expand VLAN -> F is not correct.

Question 3
By default, each port in a Cisco Catalyst switch is assigned to VLAN1. Which two recommendations are key to avoid unauthorized management access? (Choose two)
A. Create an additional ACL to block the access to VLAN 1.
B. Move the management VLAN to something other than default.
C. Move all ports to another VLAN and deactivate the default VLAN.
D. Limit the access in the switch using port security configuration.
E. Use static VLAN in trunks and access ports to restrict connections.
F. Shutdown all unused ports in the Catalyst switch.

Answer: B F

Question 4
Which two benefits are provided by creating VLANs? (Choose two)
A. added security
B. dedicated bandwidth
C. provides segmentation
D. allows switches to route traffic between subinterfaces
E. contains collisions

Answer: A C

Question 5
Which two link protocols are used to carry multiple VLANs over a single link? (Choose two)
A. VTP
B. 802.1q
C. IGP
D. ISL
E. 802.3u

Answer: B D
Explanation
Cisco switches support two trunking protocols 802.1q & ISL. 802.1q is an open standard and is thus compatible between most vendors’ equipment while Inter-Switch Link (ISL) is Cisco proprietary.

Question 6
A switch is configured with all ports assigned to vlan 2 with full duplex FastEthernet to segment existing departmental traffic. What is the effect of adding switch ports to a new VLAN on the switch?
A. More collision domains will be created.
B. IP address utilization will be more efficient.
C. More bandwidth will be required than was needed previously.
D. An additional broadcast domain will be created.

Answer: D

Question 7
Which two statements about the use of VLANs to segment a network are true? (Choose two)
A. VLANs increase the size of collision domains.
B. VLANs allow logical grouping of users by function.
C. VLANs simplify switch administration.
D. VLANs enhance network security.

Answer: B D

Question 8
Cisco Catalyst switches CAT1 and CAT2 have a connection between them using ports Fa0/13. An 802.1Q trunk is configured between the two switches. On CAT1, VLAN 10 is chosen as native, but on CAT2 the native VLAN is not specified. What will happen in this scenario?
A. 802.1Q giants frames could saturate the link.
B. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send untagged frames.
C. A native VLAN mismatch error message will appear.
D. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send tagged frames.

Answer: C
Explanation
A “native VLAN mismatch” error will appear by CDP if there is a native VLAN mismatch on an 802.1Q link. “VLAN mismatch” can cause traffic from one vlan to leak into another vlan.

Question 9
Which two statements describe the Cisco implementation of VLANs? (Choose two)
A. VLAN 1 is the default Ethernet VLAN.
B. CDP advertisements are only sent on VLAN 1002.
C. By default, the management VLAN is VLAN 1005.
D. By default, the switch IP address is in VLAN 1005.
E. VLANs 1002 through 1005 are automatically created and cannot be deleted.

Answer: A E

Question 10
What are three advantages of VLANs? (Choose three)
A. VLANs establish broadcast domains in switched networks.
B. VLANs utilize packet filtering to enhance network security.
C. VLANs provide a method of conserving IP addresses in large networks.
D. VLANs provide a low-latency internetworking alternative to routed networks.
E. VLANs allow access to network services based on department, not physical location.
F. VLANs can greatly simplify adding, moving, or changing hosts on the network.

Answer: A E F