CCNP Switch FAQ: Protecting the Spanning Tree Protocol Topology

CCNP Switch FAQ: Protecting the Spanning Tree Protocol Topology

Q1. Why is it important to protect the placement of the root bridge?
a. To keep two root bridges from becoming active
b. To keep the STP topology stable
c. So all hosts have the correct gateway
d. So the root bridge can have complete knowledge of the STP topology

Answer: B

Q2. Which of the following features protects a switch port from accepting superior BPDUs?
a. STP Loop Guard
b. STP BPDU Guard
c. STP Root Guard
d. UDLD

Answer: C

Q3. Which of the following commands can you use to enable STP Root Guard on a switch port?
a. spanning-tree root guard
b. spanning-tree root-guard
c. spanning-tree guard root
d. spanning-tree rootguard enable

Answer: C

Q4. Where should the STP Root Guard feature be enabled on a switch?
a. All ports
b. Only ports where the root bridge should never appear
c. Only ports where the root bridge should be located
d. Only ports with PortFast enabled

Answer: B

Q5. Which of the following features protects a switch port from accepting BPDUs when PortFast is enabled?
a. STP Loop Guard
b. STP BPDU Guard
c. STP Root Guard
d. UDLD

Answer: B

Q6. To maintain a loop-free STP topology, which one of the following should a switch uplink be protected against?
a. A sudden loss of BPDUs
b. Too many BPDUs
c. The wrong version of BPDUs
d. BPDUs relayed from the root bridge

Answer: A
Figure: Guidelines for Applying STP Protection Features in a Network

Q7. Which of the following commands can enable STP Loop Guard on a switch port?
a. spanning-tree loop guard
b. spanning-tree guard loop
c. spanning-tree loop-guard
d. spanning-tree loopguard enable

Answer: B

Q8. STP Loop Guard detects which of the following conditions?
a. The sudden appearance of superior BPDUs
b. The sudden lack of BPDUs
c. The appearance of duplicate BPDUs
d. The appearance of two root bridges

Answer: B

Q9. Which of the following features can actively test for the loss of the receive side of a link between switches?
a. POST
b. BPDU
c. UDLD
d. STP

Answer: C

Q10. UDLD must detect a unidirectional link before which of the following?
a. The Max Age timer expires.
b. STP moves the link to the Blocking state.
c. STP moves the link to the Forwarding state.
d. STP moves the link to the Listening state.

Answer: C

Q11. What must a switch do when it receives a UDLD message on a link?
a. Relay the message on to other switches
b. Send a UDLD acknowledgment
c. Echo the message back across the link
d. Drop the message

Answer: C

Q12. Which of the following features effectively disables spanning-tree operation on a switch port?
a. STP PortFast
b. STP BPDU filtering
c. STP BPDU Guard
d. STP Root Guard

Answer: B

Q13. To reset switch ports that have been put into the errdisable mode by UDLD, which one of the following commands should you use?a. clear errdisable udld
b. udld reset
c. no udld
d. show udld errdisable

Answer: B

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