During demotion of this domain controller, one or more Domain Name System (DNS) records did not get removed.
Sample Event:
The deregistration of some DNS domain controller locator records was aborted at the time of this domain controller demotion because the DNS deregistrations took too long.
Manually delete the DNS records listed in the file '%SystemRoot%\System32\Config\Netlogon.dns' from the DNS database.
For more information, see:
Microsoft Help and Support for Microsoft Windows Server 2008 and above
Microsoft Knowledge Base