When you have renamed a domain there will be some registry keys left with the old domain name under HKLM\System\CCS\Services\NTDS\Parameters

Name: “Configuration NC”
Type: reg_sz
Value: CN=Configuration,DC=oldname,DC=com

Name: “Machine DN Name”
Type: reg_sz
Value: CN=NTDS Settings,……,CN=Configuration,DC=oldname,DC=com

Name: “Src Srv objectGuid”
Type: reg_binary
Value: <some_DC>.oldname.com

Those keys where created by LSASS.exe when the DC was created with DCPROMO. Rendom.exe will not modify them. They are not vital and are not in use. You can update those keys for consistency if you like.

Credit to Ned Pyle at AskDS for the information.