Forest Functional Level:-

Lowest domain functional level determines the highest functional level of the forest.


Windows server 2000 Functional level:

•  All domain controller must be domain functionality of server 2000 native or above.
• Basic Active directory functionality.

Windows server 2003 Functional level:

• All domain controller must be functionality of server 2003 or above.
• New Features

1. Forest trust.
2. Rename the domains
3. Linked value replication( only the changes can be replicated instead of entire group)
4. Improved knowledge consistency checker
5. Convert a intorg person object to a user object and reverse
6. It supports only windows server 2008 RODC.
7. Deactivation of attributes and classes in the schema.

Windows server 2008 Functional Level:

• All domain controller must be functionality of server 2008 or above.

Windows server 2008R2  Functional Level:

• All domain controller must be functionality of server 2008R2 or above.
• It supports Active directory Recyclibin.