You must be a member of the Domain Admins group.
Reboot will be required
To rename a DC with the name from MY-SERVER in the PMLAB.LOCAL domain to DC-SERVER follow the next steps:
1. Open Command Prompt and type:
NETDOM computername MY-SERVER.PMLAB.LOCAL /add:DC-SERVER.PMLAB.LOCAL
This command will update the service principal name (SPN) attributes in Active Directory for this computer account, and register DNS resource records for the new computer name. The SPN value of the computer account must be replicated to all DCs for the domain, and the DNS resource records for the new computer name must be distributed to all the authoritative DNS servers for the domain name. If the updates and registrations have not occurred prior to removing the old computer name, then some clients may be unable to locate this computer using the new or old name. Therefore, it’s very important to wait till the Active Directory replication finishes a replication cycle. You can check that by using tools such as REPADMIN and REPLMON.
You can verify the new name was indeed added to the computer object by viewing it through ADSIEDIT.MSC (which, for Windows Server 2008, is installed by default). Navigate to the computer object and right-click it. Select Properties:
Scroll down in the list of available attributes till you reach the attribute called msDS-AdditionalDnsHostName.
2. Ensure the computer account updates and DNS registrations are completed, then type:
NETDOM computername MY-SERVER.PMLAB.LOCAL /makeprimary:DC-SERVER.PMLAB.LOCAL
Again, you can inspect the change with ADSIEDIT.MSC. Scroll down in the list of available attributes for the computer object (notice how the server now appears with the new name) till you reach the attribute called msDS-AdditionalDnsHostName.
Notice that the old name should appear in the attribute’s properties.
3. Restart the computer.
4. From the command prompt, type:
NETDOM computername DC-SERVER.PETRI.LOCAL /remove:MY-SERVER.PMLAB.LOCAL
5. Make sure that the changes have successfully been replicated to all the DCs.
Adapted from Perti IT Knowledge base