Enabling Windows Server 2003 Functional Levels in a Mixed Windows 2000 Environment

  • Article

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

If your Windows 2000 forest includes one or more domains that contain Windows NT 4.0–based domain controllers, those domains are in Windows 2000 mixed mode. Domains that include only Windows 2000–based domain controllers might be in Windows 2000 mixed mode or native mode. Functional levels in a mixed Windows 2000 forest are set by default when you deploy the first Windows Server 2003–based domain controller.

For more information about deploying Windows Server 2003 in a mixed Windows 2000 environment, see "Upgrading from Windows 2000 Domains to Windows Server 2003 Domains" in this book.

You can introduce a Windows Server 2003–based domain controller in a mixed environment in one of two ways:

  • By installing a new Windows Server 2003–based domain controller.

  • By upgrading an existing Windows 2000 domain controller in the forest to Windows Server 2003.

Functional levels are set at the following levels by default, and remain at these levels until they are raised manually:

  • Windows 2000 mixed or Windows 2000 native domain functional level, depending on whether the domain was in mixed mode or native mode prior to the upgrade.

  • Windows 2000 forest functional level.

If the domain functional level is set to Windows 2000 mixed after the initial upgrade, the domain must remain at that level for as long as Windows NT 4.0–based domain controllers are in the domain. If you upgrade all Windows NT 4.0–based domain controllers to either Windows 2000 or Windows Server 2003 and decommission the Windows NT 4.0–based domain controllers that you do not intend to upgrade, you can raise the domain functional level to Windows 2000 native.

If the domain functional level is set to Windows 2000 native after the initial upgrade, the domain must remain at that level for as long as Windows 2000–based domain controllers are operating in the domain.

Note

  • This also applies to Windows NT 4.0 environments in which you intend to deploy one or more Windows 2000 domain controllers in the future. After the initial upgrade, the domain must remain at a functional level of Windows 2000 mixed.

After you upgrade all Windows 2000–based domain controllers to Windows Server 2003, you can raise the functional levels of the domains in the forest to Windows Server 2003. Before you raise the domain functional level, you must verify that no Windows NT 4.0–based domain controllers remain in the domain. For more information about identifying Windows NT 4.0–based domain controllers in a domain, see "Enabling Windows Server 2003 Functional Levels in a Windows NT 4.0 Environment" earlier in this chapter.

If all domain controllers in the domain are running Windows Server 2003, you can raise the domain functional level from Windows 2000 mixed to Windows Server 2003 directly. Alternatively, you can raise the functional level step by step — from Windows 2000 mixed to Windows 2000 native and then to Windows Server 2003.

After you upgrade all domain controllers in the forest to Windows Server 2003 and raise all domains to the Windows 2000 native or Windows Server 2003 functional level, you can raise the forest functional level to Windows Server 2003. This automatically raises the functional level of any remaining domains that are operating at the Windows 2000 native functional level to Windows Server 2003.