All the servers on the network run Windows Server 2003 server and all the client computers run
Windows XP.
The network contains three domain controllers named ABC-DC1, ABC-DC2 and ABC-DC3. The
System State Data of each domain controller is backed up on a nightly basis.
Recently an organizational unit (OU) has been mistakenly deleted from the AD.
What is the quickest way to restore the deleted OU?

A.
Reboot the domain controller in Safe Mode then use Windows Backup.

B.
Reboot the domain controller in Directory Services Restore Mode then perform an authoritative
restore of the subtree where the OU was deleted using the Ntdsutil utility.

C.
Reboot the domain controller in Directory Services Restore Mode then perform a non-authoritative restore of the subtree where the OU was deleted using the Ntdsutil utility.

D.
Reboot the domain controller using the Last Known Good Configuration.

E.
Use Active Directory Sites and Services to force replication from another domain controller.

Explanation:
To restore a deleted OU, you need to first restart a domain controller in Directory
Services Restore Mode. Restarting in Directory Services Restore Mode takes the domain
controller offline. In this mode, the server is not functioning as a domain controller.
You need to then use the Ntdsutil utility to perform an authoritative restore operation of the
appropriate subtree. NTDSUTIL is used to tell Active Directory not to over-write the OU that you
wish to recover.
In case an OU is deleted from your Windows Server 2003 Active Directory, you cannot use a
normal restore because it will not work under these circumstances. What will happen is that other
Windows 2003 domain controllers will have later Update System Number and over write the
restore, and delete the OU, so you are back where you started. What you need in this situation is
the Directory Restore option from the F8 menu.
To prepare for a Directory Service Restore, first complete a normal restore and take the Windows
Server 2003 offline. Then reboot, select the special Directory Service Restore mode at the F8
menu. Next run NTDSUTIL to tell Active Directory not to over-write the OU that you wish to
recover.
Reference: Introduction to Boot Options for Windows Server 2003 / 4. Directory Services Restore -NTDSUTIL

http://www.computerperformance.co.uk/w2k3/disaster_recovery_boot.htm#Directory_Services_Re
store_-_NTDSUTIL