In the VRRP hot backup scenario, restart the master WAC and AP switching is normal. After the original master WAC completes the restart, all APs are in fault state and the service is interrupted…

Question

Options

• AIf the device is not configured with vrrp recover-delay, the restarted WAC may immediately
• BThe CAPWAP address between the active and standby WACs does not use a virtual address
• CConfiguration synchronization is not enabled for the active and standby WACs
• DHSB is not enabled

• A
  7% (3)
• B
  78% (36)
• C
  4% (2)
• D
  11% (5)

Explanation

Option B is correct because APs establish their CAPWAP tunnels to a specific IP address. If that address is the WAC's physical IP rather than the VRRP virtual IP, APs that failed over to the backup WAC connected using the backup's physical IP. When the original master restarts and reclaims the VRRP master role, it holds the virtual IP again - but it also aggressively tries to re-acquire AP management, conflicting with the backup's existing CAPWAP sessions and leaving all APs in a fault state. Using the virtual IP as the CAPWAP address ensures APs always follow whichever WAC currently owns that virtual IP, making failover and failback seamless.

Why A is wrong: vrrp recover-delay prevents the returning master from immediately preempting, which reduces flapping - but it is a mitigation, not a root cause. Even without it, the symptom would be rapid role-switching, not a permanent fault state for all APs.

Why C is wrong: Config sync ensures the backup has the same configuration, but the scenario already confirms APs switched to the backup successfully, meaning config was adequate. The problem occurs during failback, not the initial failover.

Why D is wrong: HSB (Hot Standby Backup) synchronizes session/state data so the backup can immediately serve APs without re-association. Its absence would cause issues during the initial failover, but the question states that switchover was normal - ruling out HSB as the cause.

Memory tip: Think "APs call home by address - virtual address = follows the boss (VRRP master), physical address = calls a specific person who may no longer be in charge." If APs dial a physical IP, they get stranded when roles change.

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