DNS Mixed Mode Vs Native Mode

The mode of a domain restricts OS(Operating system) of domain controllers (DCs) in that domain to be run. In a mixed-mode domain, All Windows 2000, Windows Server 2003 and Windows NT domain controllers can run. but In a native-mode domain, Windows 2000 DCs run in windows 2000 domains and Windows Server 2003 domain controllers in windows 2003 domain.

Mixed mode imposes following limitations:

1. The domain cannot contain Universal security groups.

2. Groups in the domain cannot have their scope or type changed.

3. The domain cannot have nested groups (aside from global groups in domain local groups) 4.Account modifications sent to Windows NT BDCs, including password changes, must go through PDC Emulator for the domain.

5. The domain cannot use SID History.

The domain mode can be changed only from mixed to native mode. But not vice-verse.

Only by restoring entire Active Directory environment from a previous backup can go to mixed mode.