Spanning Tree Protocol - Spanning Tree Protocol

What are the distinct functions of layer 2 switching that increase available bandwidth on the network?

Address learning
Routing
Forwarding and filtering
Creating network loops
Loop avoidance
IP addressing

A.	1, 3 and 5
B.	2, 4 and 6
C.	2 and 6
D.	3 and 5

Answer: Option A

Explanation:

Layer 2 features include address learning, forwarding and filtering of the network, and loop avoidance.

What is the result of segmenting a network with a bridge (switch)?

It increases the number of collision domains.
It decreases the number of collision domains.
It increases the number of broadcast domains.
It decreases the number of broadcast domains.
It makes smaller collision domains.
It makes larger collision domains.

A.	1 and 5
B.	2, 3 and 5
C.	3, 4 and 6
D.	1, 3 and 6

Answer: Option A

Explanation:

Bridges break up collision domains, which would increase the number of collision domains in a network and also make smaller collision domains.

If a switch receives a frame and the source MAC address is not in the MAC address table but the destination address is, what will the switch do with the frame?

A.	Discard it and send an error message back to the originating host
B.	Flood the network with the frame
C.	Add the source address and port to the MAC address table and forward the frame out the destination port
D.	Add the destination to the MAC address table and then forward the frame

Answer: Option C

Explanation:

Since the source MAC address is not in the MAC address table, the switch will add the source address and the port it is connected to into the MAC address table and then forward the frame to the outgoing port.

What command will display the forward/filter table?

A.	show mac filter
B.	show run
C.	show mac address-table
D.	show mac filter-table

Answer: Option C

Explanation:

The command show mac address-table displays the forward/filter table on the switch.

You need to allow one host to be permitted to attach dynamically to each switch interface. Which two commands must you configure on your catalyst switch to meet this policy?

Switch(config-if)# ip access-group 10
Switch(config-if)# switchport port-security maximum 1
Switch(config)# access-list 10 permit ip host 1
Switch(config-if)# switchport port-security violation shutdown
Switch(config)# mac-address-table secure

A.	1 and 3
B.	2 and 4
C.	2, 3 and 5
D.	4 and 5

Answer: Option B

Explanation:

The switchport port-security is an important command, and it's super easy with the CNA; however, from the CLI, you can set the maximum number of MAC addresses allowed into the port, and then set the penalty if this maximum has been passed.

Which of the following is a layer 2 protocol used to maintain a loop-free network?

A.	VTP
B.	STP
C.	RIP
D.	CDP

Answer: Option B

Explanation:

The Spanning Tree Protocol is used to stop switching loops in a switched network with redundant paths.

You want to run the new 802.1w on your switches. Which of the following would enable this protocol?

A.	Switch(config)# spanning-tree mode rapid-pvst
B.	Switch# spanning-tree mode rapid-pvst
C.	Switch(config)# spanning-tree mode 802.1w
D.	Switch# spanning-tree mode 802.1w

Answer: Option A

Explanation:

802.1w is the also called Rapid Spanning Tree Protocol. It is not enabled by default on Cisco switches, but it is a better STP to run since it has all the fixes that the Cisco extensions provide with 802.1d.

Your switch has a port status LED that is alternating between green and amber. What could this indicate?

A.	The port is experiencing errors.
B.	The port is shut down.
C.	The port is in STP blocking mode.
D.	Nothing; this is normal.

Answer: Option A

Explanation:

When you connect to a switch port, at first the link lights are orange/amber, and then they turn green, indicating normal operation. If the link light is blinking, you have a problem.

Spanning Tree Protocol - Spanning Tree Protocol

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