How to Select the Appropriate Restore Method?

You select the appropriate restore method by considering:

Circumstances and characteristics of the failure. The two major categories of failure, From an Active Directory perspective, are Active Directory data corruption and hardware failure.

Active Directory data corruption occurs when the directory contains corrupt data that has been replicated to all domain controllers or when a large portion of the Active Directory hierarchy has been changed accidentally (such as deletion of an OU) and this change has replicated to other domain controllers.