For BIG-IP high-availability (HA) pairs, F5’s recommended upgrade workflow prioritizesservice continuity,predictable failover, andminimal downtime. The established best-practice sequence is:
Upgrade the standby unit first
Because the standby device is not passing traffic, upgrading and rebooting it does not impact production.
Boot the standby unit into the newly installed version
Once online, the administrator verifies basic health, device sync status, cluster communication, and module functionality.
Perform a controlled failover to the upgraded unit
Traffic shifts to the newly upgraded device, allowing validation of the configuration and operational behavior under real traffic loads.
Upgrade the second device (now standby)
The previously active device becomes standby after failover, allowing it to be safely upgraded and rebooted without interruption.
This phased approach ensures only one device is unavailable at a time, allowing continuous traffic flow throughout the upgrade process.
Why the Correct Answer is C
OptionCexactly matches F5’s documented production-safe upgrade method:
Upgrade thestandbynode first
Reboot into new image
Failover to upgraded device
Validate
Upgrade the remaining (now-standby) device
This procedure minimizes risk and traffic disruption.
Why the other options are incorrect:
A. Upgrade the active node first
Upgrading the active device requires removing it from service and failing over abruptly. This is not recommended and increases service disruption risk.
B. Resetting device trust
Resetting trust is unnecessary and can disrupt configuration sync, peer communication, and cluster operation. It is not part of any standard upgrade workflow.
D. Upgrading and rebooting both nodes simultaneously
This would causetotal outage, because both HA members would be unavailable at the same time.
