For pre-W2K clients, the PDC emulator acts as a Windows NT PDC. It processes password changes from clients and replicates updates to the BDCs.

In native-mode, the PDC emulator receives preferential replication of password changes performed by other DCs in the domain. If a password was recently changed, that change takes time to replicate to every DC in the domain. If a logon authentication fails at another DC due to a bad password, that DC will forward the authentication request to the PDC emulator before rejecting the log on attempt.