from RT#15534: Kea API - Statistics & HA - Inaccurate Counters and Unable to get HA
I'm unsure why this is, but the statistics for my subnets in Kea aren't right when I query each server in HA. It seems the active server returns the correct statistics, but then the backup one returns its last known best statistics
HA uses commands in the Lease Commands hook library to send lease updates to peer(s). These commands do not (yet) update the local statistics, thus adding, updating (state), or deleting a lease via these commands does NOT update the related lease statistics. . Thus in an HA pair (or any other multi-server setup), the number of assigned leases reflects the number of addresses assigned by THAT peer.