How to Restore Windows Server 2003 Active Directory
Windows Server 2003 OS, we can restore the Active Directory database if it get corrupted / destroyed because of hardware or software failures. We must restore the Active Directory database when objects in Active Directory are changed / deleted.
Tombstone : In Windows Server 2003 there is an option to restore Active Directory objects that have been deleted and are in a "tombstone". These items are hidden from the GUI and await their cleanup by a process called "garbage collection".
Below are the three methods available to restore Active Directory from backup media: Primary Restore, Normal Restore (i.e. Non Authoritative), and Authoritative Restore.
Primary Restore: This rebuilds the first domain controller in a domain when there is no other way to rebuild the domain. Perform a primary restore only when all the domain controllers in the domain are lost, and you want to rebuild the domain from the backup. Members of the Administrators group can perform the primary restore on local computer. On a domain controller, only members of the Domain Admins group can perform this restore
Normal Restore: This reinstates the Active Directory data to the state before the backup, and then updates the data through the normal replication process. Perform a normal restore for a single domain controller to a previously known good state.
Authoritative Restore: This tandem with a normal restore. An authoritative restore marks specific data as current and prevents the replication from overwriting that data. The authoritative data is then replicated through the domain. Perform an authoritative restore for individual object in a domain that has multiple domain controllers. When you perform an authoritative restore, you lose all changes to the restore object that occurred after the backup. You need to use the NTDSUTIL command line utility to perform an authoritative restore. You need to use it in order to mark Active Directory objects as authoritative, so that they receive a higher version recently changed data on other domain controllers does not overwrite System State data during replication.
Example, if you inadvertently delete or modify objects in Active Directory, and those objects were thereafter replicated to other DCs, you will need to authoritatively restore those objects so they are replicated or distributed to the other servers. If you do not authoritatively restore the objects, they will never get replicated or distributed to your other servers because they will appear to be older than the objects currently on your other DCs. Using the NTDSUTIL utility to mark objects for authoritative restore ensures that the data you want to restore gets replicated or distributed throughout your organization.
On the other hand, if your system disk has failed or the Active Directory database is corrupted, then you can simply restore the data normally without using NTDSUTIL. After rebooting the DC, it will receive newer updates from other DCs.