A. You can use Ntdsutil to check the AD database. You must have booted into Directory Services Restore Mode. (At boot time, press F8 and select Directory Services Restore Mode.) Start Ntdsutil. With Windows Server 2008 and later, you must first select an active instance via the Activate Instance NTDS option, which loads the directory service; although, if others were present, they could be activated instead. Access the File Maintenance section via the Files command, and run the Integrity check. You can also perform a Semantic check via the Semantic Database Analysis module