This question is about a single domain and single site. In summer of 2007, we upgraded our NT4 domain structure to Windows Server 2003 Active Directory. We're still running Windows Server 2003 R2 SP2 with the latest patches as of today. The Domain and Forest Functional Level were set to Windows Server 2003 interim mode during the migration and for some reason we left it at that mode ever since to be sure that things work without any problem. We have removed all NT4 servers (PDC/BDC) from the network. There are no NT4 or Windows 2000 domain controllers at all. We now want to raise the Domain Functional Level to Windows Server 2003 Native mode but unsure how it is going to affect the client machines. Believe it or not, we still have NT4 workstations and Windows 95 machines, authenticating to the AD domain. Will the Windows Server 2003 Native mode affect our client machines ability to login to the domain?

Hi, Actually, it is called Windows Server 2003 mode, which you can consider to be Windows Server 2003 native mode (although it isn't called that to avoid confusion with Windows 2000 native mode). If you would like to upgrade to Windows Server 2003 Domain Functional level, all the domain controllers should install Windows Server 2003. However, there is no limitation on the clients. The whole range of clients and member servers can still join the domain. The following links can be reference: How to raise Active Directory domain and forest functional levels http://support.microsoft.com/kb/322692 Raising domain and forest functional levels http://technet.microsoft.com/en-us/library/cc781864(WS.10).aspx SolutionBase: Understanding mixed and native modes in Windows Server 2003 http://www.techrepublic.com/article/solutionbase-understanding-mixed-and-native-modes-in-windows-server-2003/5140371 Regards, Cecilia Zhou -------------------------------------------------------------------------------- Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hello, raising DFL/FFL has no effects on client computers. It has only affects on DCs as in your case, all DCs should be 2003 server or higher. Before raising, make sure that all your DCs are 2003 and higher. After raising your DFL, you can raise also your FFL to Windows Server 2003. In this case, all DCs in your forest should be 2003 server or higher. This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. Microsoft Student Partner 2010 / 2011 Microsoft Certified Professional Microsoft Certified Systems Administrator: Security Microsoft Certified Systems Engineer: Security Microsoft Certified Technology Specialist: Windows Server 2008 Active Directory, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Network Infrastructure, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Applications Infrastructure, Configuration Microsoft Certified Technology Specialist: Windows 7, Configuring Microsoft Certified IT Professional: Enterprise Administrator

Thanks to Cecilia and Mr X for your response. That's exactly what we thought; it'll only affect domain controllers but won't affect clients but we weren't 100% sure about it. Since we don't plan to install anything older than Windows Server 2003, we should be ok with this change. Thanks again.

Hi, Appreciate your update and response. I am glad to hear that the information I offered is helpful. If you have any other questions or concerns, please do not hesitate to post in our forum. It is always our pleasure to be of assistance. Have a nice day! Regards, Cecilia Zhou -------------------------------------------------------------------------------- Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.