Backup Exec FAQ

If you are restoring Active Directory data, you will generally be restoring it for one of two reasons:

• You are restoring an entire domain controller, and you need some Active Directory data for it to start up correctly
• You need to restore all or part of your Active Directory data to a prior state, such as if you've accidentally deleted an organisational unit

In the second case you need to perform an authoritative restore, in the first a non-authoritative restore is adequate. 

When Active Directory starts up it takes various steps to ensure that the data it contains is consistent. Normally when a domain controller starts it connects to other domain controllers to ensure that it receives any updates that have occurred in the time the domain controller has been down. In order to do this it must have some Active Directory data to start with, which is why data needs to be restored to a domain controller as part of a disaster recovery.

An authoritative restore allows Active Directory data to be restored, and then have its sequence number incremented, to make it appear to be newer than it actually is. If you perform an authoritative restore on a domain controller then restart it, it will tell other domain controllers that it has the latest updates, and they will replicate data from the restored copy of Active Directory.

So what scenarios require what sort of restore?

• If you have only one domain controller and are performing a disaster recovery on it, there is no need to perform an authoritative restore. There is only one copy of Active Directory data, so no update sequences occur anyway.
• If you have more than one domain controller and are performing a disaster recovery on one domain controller, there is no need to perform an authoritative restore. When the restored domain controller restarts it will receive the latest data from another domain controller.
• If you have more than one domain controller and are performing a disaster recovery on all your domain controller, there is no need to perform an authoritative restore. When the restored domain controllers restart they will automatically negotiate the latest data.
• If you are restoring old Active Directory data and want to revert to the old data, you need to perform an authoritative restore.

Last update : 20-11-2007 14:32

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