The PDC emulator processes password changes from earlier-version clients and other domain controllers on a best-effort basis; ...

The PDC emulator processes password changes from earlier-version clients and other domain controllers on a best-effort basis; handles password authentication requests involving passwords that have recently changed and not yet been replicated throughout the domain; and, by default, synchronizes time. If the domain controller {0} cannot connect to the PDC emulator, domain controller {0} cannot process authentication requests, it may not be able to synchronize time, and password updates cannot be replicated to it.