A BIG-IP Administrator makes a configuration change to a Virtual Server on the Standby device of an HA pair. The HA pair is currently configured with…

In a standard BIG-IP high-availability (HA) active/standby pair with Auto-Sync enabled, the configuration on the Active device is considered the master or source configuration. The primary purpose of Auto-Sync is to ensure the Standby device's configuration is a mirror of the Active device's. When an administrator makes a change directly on the Standby device, that device becomes temporarily out-of-sync. The next time a synchronization event occurs (which is automatically triggered by a configuration save on the Active device), the system will propagate the configuration from the Active device to the Standby device. This synchronization process will overwrite any local changes made on the Standby unit, effectively undoing them.

A. This describes the most common trigger for the synchronization, but option C more accurately describes the mechanism that undoes the change.

B. Configuration synchronization propagates from the Active to the Standby device. A change on the Standby will not be propagated to the Active device.

D. The change made on the Standby device will be overwritten and lost during the next sync; it will not take effect across the HA pair.

1. F5 Networks, BIG-IP Device Service Clustering: Administration, Version 16.1.

Chapter: Managing BIG-IP Device Groups

Section: Synchronizing configuration data > Understanding automatic synchronization

Quote: "However, if you have a standard active/standby configuration, you should make configuration changes on the active device only. If you make a change on the standby device, that change is lost when the active device synchronizes its configuration to the standby device." This directly confirms that changes on the standby are undone by the synchronization process.

2. F5 Networks, K14856: The 'Recommended' and 'Not Recommended' ways to configure device groups.

Section: Not Recommended

Content: This knowledge base article reinforces the principle that in an active-standby pair, all configuration changes should be performed on the active unit. Making changes on the standby unit can lead to a loss of those changes upon the next configuration synchronization from the active unit. This supports the conclusion that the change will be undone.