Sometimes one of Microsoft's 'single point of failure' problems bites back, and a dead DC which was housing the 5 FSMO roles is one of the most irksome. The obvious solution is to restore a working backup, but sometimes that might not be immediately possible - dead hardware, corrupt backup, need to get it working 'right now' and so on.
Assuming [!] one has other DCs available, then this bit of Powershell will force the FSMO roles to a new DC.
$fsmoRoles = @('SchemaMaster','DomainNamingMaster','InfrastructureMaster','PDCEmulator','RIDMaster' )
$targetDC = Get-ADDomainController -Identity FQDN-of-dead-DC
Move-ADDirectoryServerOperationMasterRole ` -Identity $targetDC ` -OperationMasterRole $fsmoRoles ` -Confirm:$false ` -WhatIf
Note the '- WhatIf' flag which shows what would happen but does not actually execute it, so it returns this:
What if: Moves the specified operation master (FSMO) role to the specified directory server.
What if: Moves the specified operation master (FSMO) role to the specified directory server.
What if: Moves the specified operation master (FSMO) role to the specified directory server.
What if: Moves the specified operation master (FSMO) role to the specified directory server.
What if: Moves the specified operation master (FSMO) role to the specified directory server.
PS C:WINDOWSsystem32>
If you are happy with this then replace the -WhatIf with a -Force, and then execute the command.
Test for the correct migration of all FSMO roles with
Get-ADDomainController -Filter * | Select-Object ` HostName, Site, OperatingSystem
and
dsquery server -forest
Finally, clean up the debris..
Delete the old DC from ADSS
Delete any old DNS records
Run dcdiag /v /fix to fix any remaining errors.
See also..