Rapid PVST+ Practice Questions

Answers and explanations appear when you work through the set above.

1. Which set lists the port states used by Rapid PVST+?

   • Discarding, learning, forwarding
   • Blocking, listening, learning, forwarding
   • Listening, learning, forwarding, disabled
   • Down, init, exstart, full

2. Which RSTP port role provides a backup path to the root bridge through a different switch, and moves quickly to forwarding if the root port fails?

   • Alternate port
   • Backup port
   • Designated port
   • Disabled port

3. Which command makes a switch the root bridge for VLAN 10 by lowering its bridge priority automatically?

   • spanning-tree vlan 10 root primary
   • spanning-tree vlan 10 priority 65535
   • spanning-tree root vlan 10 enable
   • spanning-tree vlan 10 cost 1

4. What is the default bridge priority on a Cisco switch before the VLAN ID is added?

   • 32768
   • 4096
   • 24576
   • 61440

5. Which switch becomes the root bridge?

   • The one with the lowest bridge ID, made of priority plus MAC address
   • The one with the highest MAC address
   • The one with the most ports
   • The one that boots first

6. What does PortFast do on an access port connected to a PC?

   • It moves the port to forwarding immediately, skipping the normal spanning tree convergence delay
   • It disables spanning tree on the entire switch
   • It raises the port speed to 1 Gb/s
   • It makes the port a trunk

7. What does root guard do when it is enabled on a port?

   • It puts the port into a root-inconsistent state if a superior BPDU is received, preventing a new root from being elected through that port
   • It shuts the port down permanently when any BPDU arrives
   • It blocks the port if BPDUs stop arriving
   • It makes the local switch the root for all VLANs

8. What does loop guard protect against?

   • A non-designated port moving to forwarding because BPDUs stopped arriving, for example after a unidirectional link failure
   • A user connecting a rogue DHCP server
   • Broadcast storms caused by a host
   • MAC address spoofing on access ports

9. What does BPDU guard do to a PortFast-enabled port that receives a BPDU?

   • It places the port in the err-disabled state
   • It ignores the BPDU
   • It raises the port to root port
   • It forwards the BPDU to the whole VLAN

10. Two paths reach the root bridge with the same total root path cost. Which value does a switch compare next when choosing its root port?

    • The lowest sender bridge ID
    • The highest port priority
    • The highest local MAC address
    • The lowest port number on the local switch only

11. Which show command displays the root bridge, bridge ID, and each port's role and state for VLAN 10?

    • show spanning-tree vlan 10
    • show vlan id 10
    • show interfaces trunk
    • show mac address-table vlan 10

12. A user connected a small STP-capable switch to an access port, and BPDU guard err-disabled the port. To restore service, an AI assistant recommends no spanning-tree bpduguard enable on that port. What is the best evaluation?

    • Accept it, because BPDU guard should only be enabled on trunk ports
    • Reject it: BPDU guard worked as intended, so remove the rogue switch, then recover the port
    • Accept it, but also disable PortFast so that the port can safely receive BPDUs
    • Reject it, and enable root guard on the port instead so the switch is tolerated

13. An AI assistant states that SW2 will become the root bridge for VLAN 10 because it has the lowest MAC address. show spanning-tree vlan 10 reports SW1's bridge priority as 24586 and SW2's as 32778. Which evaluation is correct?

    • The claim is correct, because the lowest MAC address always wins the root election
    • The claim is correct, because 32778 includes a larger extended system ID than 24586
    • The claim is wrong, because SW1 has the lower priority, which is compared before the MAC address
    • The claim is wrong, because the switch with the most designated ports becomes root