Windows 2000 domains have two modes: mixed and native. Mixed-mode domains let Windows NT 4.0 BDCs participate in a Win2K domain.
In a native mode domain, only Win2K-based domain controllers (DCs) can participate in the domain. In addition, NT 4.0-based BDCs can�t act as DCs. Switching to native mode lets you use the new universal groups, which you can nest inside one another (unlike global groups). NetBIOS-based clients can still use their NetBIOS domain names to log on, even in native mode.
To switch a Win2K domain to native mode, perform the following steps.
Check all the DCs in the domain. Reboot DCs that display Native Mode. Rebooting the DCs might take 15 minutes or longer.
If you can�t contact a DC (e.g., if the DC is in a remote site and connects only periodically), the remote DC will switch to native mode the next time replication occurs.