Question

What are the necessary conditions and permissions required to raise domain or forest functional levels?

Answer 1

Functional levels are an extension of the mixed mode and the native mode concepts that were introduced in Microsoft Windows 2000 Server to activate new Active Directory features. Some additional Active Directory features are available when all the domain controllers are running the newest Windows Server version in a domain or in a forest, and when the administrator activates the corresponding functional level in the domain or in the forest.



To activate the newest domain features, all the domain controllers must be running the newest Windows Server operating system version in the domain. If this requirement is met, the administrator can raise the domain functional level.

To activate the newest forest-wide features, all the domain controllers in the forest must be running the Windows Server operating system version that corresponds to the desired forest functional level. Additionally, the current domain functional level must already be at the newest level. If these requirements are met, the administrator can raise the forest functional level.



Generally, the changes to the domain and forest functional levels are irreversible. If the change can be undone, a forest recovery must be used. With the Windows Server 2008 R2 operating system, the changes to domain functional levels and to forest functional levels can be rolled back.

Note The newest domain functional levels and the newest forest functional levels affect only the way that the domain controllers operate together as a group. The clients that interact with the domain or with the forest are unaffected. Additionally, applications are unaffected by changes to the domain functional levels or to the forest functional levels. However, applications can take advantage of the newest domain features and of the newest forest features.