When a domain contains more than one domain controller, Active Directory replicates directory objects, such as users, groups, organizational units, and computers, to all the domain controllers in that domain. Authoritative restore is a method to recover objects and containers that have been deleted for AD DS. An authoritative restore marks specific data as current and prevents the replication from overwriting that data. The authoritative data is then replicated throughout the domain.
The process for performing an authoritative restore of AD is the same as a Non-authoritative restore except for one step. After the restore of AD is complete in DSRM and then, before restarting, you manually run Ntdsutil, and the mark the object that you want to restore as Authoritative.
This video tutorial shows how to perform backup DC and Authoritative Domain Controller Restore for Windows Server 2008 and Windows Server 2008 R2.