Include SystemState during backup of a DC (and do so for each DC)
if you are using the built-in ntbackup. If you are using a third-party
backup software read their docs to see how to get a consistent system
state backup. Note that there really is no such thing as a backup of
Active Diirectory service. One can backup the instance of the Active
Directory data on DC1, or on DC2, etc. and the restored needs to
be back to the same DC.
