Answer:
PDC emulator master.
Explanation:
The PDC or primary domain control emulator master is the primary domain control for windows NT and other pre-windows operating system like windows 2000, windows 98, windows 95. It help the windows NT4.0 to authenticate and process passwords, since it can inter-replicate passwords from other domain controls in an active directory. It is the first server used as a domain control in a domain and can only be allowed in one domain control at a time in an active directory.