How do we Backup Active Directory?
Backing up Active Directory is necessary to maintain an Active Directory database. You can back up Active Directory by employing the Graphical User Interface (that is, GUI) and command-line tools which the Windows Server 2003 family offers.
You often backup the system state data on domain controllers and hence you can restore the most present data. By establishing a customary backup schedule, you have a better possibility of recovering data whenever required.
To make sure a good backup comprises at least the system state data and contents of the system disk, you should be aware of the tombstone life-time. By default, the tombstone is of 60 days. Any backup more than 60 days is not a good backup. Plan to backup as a minimum of two domain controllers in each domain, one of at least one backup to allow an authoritative restore of the data whenever required.