I would like to deepen my knowledge in backup and recovery strategies. Therefore I did some research and read some articles about backing up and recovering domain controllers, but there are some things I don't fully understand, because most articles assume, that there are at least two domain controllers.
Why does everyone recommend at least two domain controllers? What exactly are the risks of only having one domain controller in a small company, where the time for the restore process is not important compared to the costs of a second server? Will there be real additional risks for the data stored in the Active Directory or is the recommendation only based on the risk of a longer downtime?
Will the problems mentioned by Microsoft (http://technet.microsoft.com/en-us/library/cc535164.aspx
), regarding “Restoration of a relative identifier (RID) master can result in corruption of the Active Directory database.” and “Restoration of the schema master (SID) can result in orphaned objects.” will affect a single domain controller or is this only a problem with more than one domain controller? What exactly will cause those problems?
If I want to restore a single domain controller, is there anything to do besides restoring a backup I did with backup software with an online-image-feature? As far as I understand an unauthoritative system state restore won’t provide any additional data and is only useful if the server is still in a working condition and something was damaged or deleted in the active directory. And an authoritative system state restore is not needed for a single domain controller (and should never be needed if you use recommended restore procedures).
Is there anything additional to consider regarding the backup and recovery of a domain controller, if Exchange 2010 is installed on the same server? I know about the Exchange database and logfiles, but will it affect the strategy for backup and recovery of the DC/AD part?