When a directory server crashes, its connection to the replication server is lost. Recent changes that the directory server has processed and committed to its database might not yet have been transmitted to any replication server.
When a directory server restarts, therefore, it must compare its state with the server state of the replication servers to which the directory server connects. If the directory server detects that changes are missing and not yet sent to a replication server, the directory server constructs fake operations from historical information. The directory server sends these fake operations to its replication server.
Because teh local server state is not saved after each operation, the directory server cannot trust its saved server state after a crash. Instead, it recalculates its server update state, based on historical information.