F5CABR: F5 Certified Administrator, BIG-IP RecertificationDemo

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QuestionQ13

High Availability and Failover

During a planned upgrade to a BIG-IP HA pair running in Active/Standby mode, an outage to application traffic is reported shortly after the Active unit is forced into Standby. Reverting the failover resolves the outage.

Based on the exhibit shown, what should the BIG-IP Administrator modify to avoid an outage during the next failover event?

Question Image

  • A The Tag value on the Active device
  • B The Tag value on the Standby device
  • C The Interface on the Active device to 1.1
  • D The Interface on the Standby device to 1.1
Explanation

The VLAN named VLAN-21 is configured with a Tag value of 21 on the Active device but with a Tag value of 211 on the Standby device, even though both devices use the same interface assignments (1.1 untagged, 1.2 tagged). Since BIG-IP VLANs are identified on the network by their 802.1Q tag, this mismatch means that when the Standby unit becomes Active during failover, it tags traffic differently than the upstream/downstream switches expect for that VLAN, causing traffic to be dropped and resulting in an outage. Correcting the Tag value on the Standby device so it matches the Active device's tag (21) ensures consistent VLAN tagging regardless of which unit is Active, preventing the outage on future failovers.

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