As a system administrator you work hard to make sure it never happens by having as much redundancy as you can but sooner or later you will lose a domain controller which has a role assigned to it.  If you have true redundancy you will still have a backup domain controller.

The only problem is the roles will not just transfer over.  You will need to seize them from the dead controller and give the roles to the backup domain controller.

To seize the roles it is very easy, first login into a working domain controller and go to the command prompt with administration rights.  Then follow the steps below:

1. type “ntdsutil” and press enter
2. type “roles”
3. Next type “connections” when you see “fsmo maintenance:” prompt
4. Type “connect to server <working dc’s name>” at the “server connections:” prompt
5. Enter “role” while at the “fsmo maintenance:” prompt
6. Type “Seize <FSMO Role to be transferred>” you can also use “?” to get a list of commands including all the FSMO roles.
7. Click Yes to the prompt which pops up outside of the command prompt

That’s it, your roles have been seized by the domain controller.