Which scenario will cause automatic high availability (HA) synchronization to fail?

• A. Different build versions
• B. Manually forced synchronization
• C. A force failover
• D. A configuration change to the primary NetScaler

Answer: (A)

Automatic HA synchronization requires both Citrix ADC units to run the same software build. When the two appliances have different builds, the binary and state data are not guaranteed to be compatible, so the synchronization mechanism blocks automatic sync to prevent mismatched configurations from being applied. That’s why having different build versions stops HA sync from working automatically—the two units must be on identical builds to exchange and apply the config and state reliably.

In contrast, forcing synchronization manually simply tries to sync once the builds are compatible; forcing a failover changes which unit is active but doesn’t inherently prevent subsequent sync once both sides match; a configuration change on the primary will be pushed to the secondary automatically when the build versions align. To resolve the issue, align both units to the same build/version, then the automatic HA synchronization can operate normally.