A. When you start the domain controller (DC) in Directory Restore mode, the DC sets the environment variable safeboot_option to "dsrepair." If you want to check something in ntdsutil that is allowed only in Directory Restore mode, you can "trick" the program by typing the following statement at a command prompt:

                              set SAFEBOOT_OPTION=DSREPAIR                              

Don't use this approach on a live or important machine because it could result in system damage if you try to perform system modifications when the system isn't in Directory Restore mode.