Reference: HA Synchronization

If you have enabled configuration synchronization on both peers in an HA pair, most of the configuration settings you configure on one peer will automatically sync to the other peer upon commit. To avoid configuration conflicts, always make configuration changes on the active (active/passive) or active-primary (active/active) peer and wait for the changes to sync to the peer before making any additional configuration changes.
Only committed configurations synchronize between HA peers. Any configuration in the commit queue at the time of an HA sync will not be synchronized.
The following topics identify which configuration settings you must configure on each firewall independently (these settings are not synchronized from the HA peer).

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