You can use the Windows Server 2008 domain rename process to change the names of your Active Directory domains, and you can also use it to change the structure of the domain trees in your Active Directory forest. This process involves updating the Domain Name System (DNS) and trust infrastructures as well as Group Policy and Service Principal Names (SPNs).

Domain name requirements

The following conditions must be in effect before you can begin a domain rename operation:

• Forest functionality: You can rename domains only in a forest where all of the domain controllers are running Windows Server 2008 or Windows Server 2003 Standard Edition, Windows Server 2008 or Windows Server 2003 Enterprise Edition, or Windows Server 2008 or Windows Server 2003 Datacenter Edition operating systems, and the Active Directory forest functional level has been raised to either Windows Server 2003 or Windows Server 2008. The domain rename operation will not be successful if the forest functional level is set to Windows 2000 native. For more information about forest functional levels and for procedures to determine and set forest functional levels, see Enabling Windows Server 2008 Advanced Features for Active Directory Domain Services (http://go.microsoft.com/fwlink/?LinkID=105303).
• Administrative credentials: You must have Enterprise Admins credentials to perform the various procedures for the domain rename operation. If you are running Microsoft Exchange, the account that you use must also have Full Exchange Administrator credentials.
• Control station: The computer that you use as the control station for the domain rename operation must be a member computer (not a domain controller) running Windows Server 2008 Standard Edition, Windows Server 2008 Enterprise Edition, or Windows Server 2008 Datacenter Edition.
• Distributed File System (DFS) root servers: So that you can rename a domain with domain-based DFS Namespace (DFSN) roots, all DFSN root servers must be running Windows 2000 with Service Pack 3 (SP3), Windows Server 2003, or Windows Server 2008 operating systems.
• Exchange 2003 Service Pack 1 (SP1): If your forest contains Exchange 2003 Service Pack 1 (SP1) servers, you can run the Windows Server 2008 domain rename operation, but you must also use the Exchange Domain Rename Fix-up Tool to update Exchange attributes. For more information, see Microsoft Exchange Server Domain Rename Fixup (XDR-Fixup) (http://go.microsoft.com/fwlink/?LinkID=122982). The document that accompanies this tool describes when and how to perform Exchange-related tasks. To perform a domain rename operation, Exchange must not be installed on any domain controllers. If a domain controller is running Exchange, move the Exchange data off the domain controller and then uninstall Exchange.

Note the following:

• The domain rename operation is not supported in Microsoft Exchange Server 2007 or Exchange Server 2010. DNS domain rename is supported in Exchange Server 2003. However, renaming of the NetBIOS domain name is not supported in any version of Exchange Server. Other non-Microsoft applications might also not support domain rename.

  For more information about other Microsoft applications that are incompatible with domain rename, see article 300684 (http://go.microsoft.com/fwlink/?LinkId=185229) in the Microsoft Knowledge Base.
• You can use "Checklist: Satisfying Domain Rename Requirements" in Appendix C: Checklists for the Domain Rename Operation to make sure that you have met all the necessary requirements for the domain rename operation.

Performing the Domain Rename Operation

This task provides information about performing the domain rename operation. This task describes in detail the procedures that you complete to perform the domain rename operation in your forest. Be sure that you have reviewed and completed every preliminary procedure that applies to your domain rename conditions, as described in Preparing for the Domain Rename Operation.

After you complete all the procedures in this task, the target domain name changes will be effective in your forest. The domain name changes will have propagated toall the domain controllers in your forest, as well as to the member computers in the renamed domains.

A brief period of interruption in your Active Directory forest service occurs during the time when all of the domain controllers in the forest are automatically restarting. The exact point at which the service interruption occurs is indicated in Run Domain Rename Instructions. Except for this brief period of interruption, the Active Directory Domain Services (AD DS) service should continue to be available and function normally throughout the rest of the domain rename process.

References

This article was sourced from the  thread Can you rename Windows 2008 Domain on TechNet Windows Directory Services forum and includes information from the TechNet Library.

• Swaminathan Pattabiraman [MSFT] provided the original answer the rendom.exe tool.
• Jetze Mellema (MVP) provided a pointer to the TechNet articles mashed together above.
• TechNet source articles include Introduction to Administering Active Directory Domain Rename and Performing the Domain Rename Operation.