BDC

BDC

Backup Domain Controller. In a Windows NT domain, one domain controller is the primary (the PDC) and any other domain controllers are backup ones. Each BDC synchronises regularly with the PDC, and can provide the same services as the PDC. Should the PDC fail then any of the BDCs can be promoted to replace the PDC but this promotion is a manual activity that must be done by an administrator.

From Windows 2000 onwards the concept of PDC and BDC no longer exist (although system administrators still use the terms), and all domain controllers have equal status.