Spanning Tree Protocol - Spanning Tree Protocol (2)

Layer 2 switching provides which of the following?

Hardware-based bridging (ASIC)
Wire speed
Low latency
Low cost

A.	1 and 3
B.	2 and 4
C.	1, 2 and 4
D.	All of the above

Answer: Option D

Explanation:

Switches, unlike bridges, are hardware based. Cisco says its switches are wire speed and provide low latency, and I guess they are low cost compared to their prices in the 1990s.

10.

You have two switches connected together with two crossover cables for redundancy, and STP is disabled. Which of the following will happen between the switches?

A.	The routing tables on the switches will not update.
B.	The MAC forward/filter table will not update on the switch.
C.	Broadcast storms will occur on the switched network.
D.	The switches will automatically load-balance between the two links.

Answer: Option C

Explanation:

If spanning tree is disabled on a switch and you have redundant links to another switch, broadcast storms will occur, among other possible problems.

11.

Which of the following statement is true?

A.	A switch creates a single collision domain and a single broadcast domain. A router creates a single collision domain.
B.	A switch creates separate collision domains but one broadcast domain. A router provides a separate broadcast domain.
C.	A switch creates a single collision domain and separate broadcast domains. A router provides a separate broadcast domain as well.
D.	A switch creates separate collision domains and separate broadcast domains. A router provides separate collision domains.

Answer: Option B

Explanation:

Switches break up collision domains, and routers break up broadcast domains.

12.

If you want to disable STP on a port connected to a server, which command would you use?

A.	disable spanning-tree
B.	spanning-tree off
C.	spanning-tree security
D.	spanning-tree portfast

Answer: Option D

Explanation:

If you have a server or other devices connected into your switch that you're totally sure won't create a switching loop if STP is disabled, you can use something called portfast on these ports. Using it means the port won't spend the usual 50 seconds to come up while STP is converging.

13.

In which circumstance are multiple copies of the same unicast frame likely to be transmitted in a switched LAN?

A.	During high-traffic periods
B.	After broken links are reestablished
C.	When upper-layer protocols require high reliability
D.	In an improperly implemented redundant topology

Answer: Option D

Explanation:

If the Spanning Tree Protocol is not running on your switches and you connect them together with redundant links, you will have broadcast storms and multiple frame copies.

14.

What does a switch do when a frame is received on an interface and the destination hardware address is unknown or not in the filter table?

A.	Forwards the switch to the first available link
B.	Drops the frame
C.	Floods the network with the frame looking for the device
D.	Sends back a message to the originating station asking for a name resolution

Answer: Option C

Explanation:

Switches flood all frames that have an unknown destination address. If a device answers the frame, the switch will update the MAC address table to reflect the location of the device.

15.

Which statement describes a spanning-tree network that has converged?

A.	All switch and bridge ports are in the forwarding state.
B.	All switch and bridge ports are assigned as either root or designated ports.
C.	All switch and bridge ports are in either the forwarding or blocking state.
D.	All switch and bridge ports are either blocking or looping.

Answer: Option C

Explanation:

Convergence occurs when all ports on bridges and switches have transitioned to either the forwarding or blocking states. No data is forwarded until convergence is complete. Before data can be forwarded again, all devices must be updated.

16.

What is the purpose of Spanning Tree Protocol in a switched LAN?

A.	To provide a mechanism for network monitoring in switched environments
B.	To prevent routing loops in networks with redundant paths
C.	To prevent switching loops in networks with redundant switched paths
D.	To manage the VLAN database across multiple switches
E.	To create collision domains

Answer: Option C

Explanation:

The Spanning Tree Protocol (STP) was designed to stop layer 2 loops. All Cisco switches have the STP on by default.

Spanning Tree Protocol - Spanning Tree Protocol (2)

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