Event Message:

The server computer name and computer name both claim to be the primary domain controller for the name domain. One of the servers should be demoted or removed from the domain.

Source

Event Log

Event ID

Event Type

NetLogon

System

5512

Error

Explanation:

Each domain should have only one primary domain controller (PDC). Two PDCs exist in the domain because one of the PDCs stopped working for an extended period. A backup domain controller (BDC) was then promoted to PDC. Now the original PDC is working again.

User Action:

Demote one of the PDCs.