Your company has anActive Directory domainthat runs Windows Server 2008 R2.
The Sales OU containsan OU for Computers, an OU for Groupsand an OU for Users.
You perform nightly backups. An administrator deletes the Groups OU.
Youneed to restore the Groups OU without affecting users and computers in the Sales OU.
What should you do?

A.
Perform an authoritative restore of the Sales OU.

B.
Perform a non-authoritative restore of the Sales OU.

C.
Perform an authoritative restore of the Groups OU.

D.
Perform a non-authoritative restore of the GroupsOU.

Explanation:
Answer.Perform an authoritative restore of the Groups OU.
http://technet.microsoft.com/en-us/library/cc816878%28v=ws.10%29.aspx
Performing Authoritative Restore of Active Directory Objects
An authoritative restoreprocess returns a designated, deleted Active Directory object or container of objects
to its predeletion state at the time when it was backed up. For example, you might have to perform an
authoritative restore if an administrator inadvertently deletes an organizational unit (OU) that contains a large
number of users. In most cases, there are two partsto the authoritative restore process: a nonauthoritative
restore from backup, followed by an authoritative restore of the deleted objects. If you perform a
nonauthoritative restorefrom backup only, the deleted OU is not restored because the restored domain
controller is updated after the restore process to the current status of its replication partners, which have
deleted the OU. To recover the deleted OU, after you perform nonauthoritative restore from backup and before
allowing replication to occur, you must perform an authoritative restore procedure. During the authoritative
restore procedure, you mark the OU as authoritativeand let the replication process restore it to all the other
domain controllers in the domain. After an authoritative restore, you also restore group memberships, if
necessary.