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
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
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
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
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
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
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
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
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
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.
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
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
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
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