1.10 Domain modes

There are two domain modes: mixed mode and native mode. Mixed mode is the default mode and is used when a new domain is created or when a Windows NT 4.0 PDC is upgraded to Windows 2000. Mixed mode implies that there are NT 4.0 backup DCs in the domain. One of the Windows 2000 DCs takes the FSMO role of PDC Emulator and acts as a Windows 2000 PDC in the eyes of the down-level clients and BDCs. This is quite important, because it allows Windows NT 4.0 operations to be maintained while the domain is migrated to Windows 2000. It is important to remember that in a mixed-mode environment there may be down-level BDCs. In an effort to reduce domains and consolidate resources, these BDCs use a SAM DB with the same limitation as a Windows NT 4.0 its 65-MB size.

The groups in the domain use Windows NT 4.0 behavior when operating in mixed mode, which means that groups cannot be nested. In addition, security universal groups are not available in mixed mode. When all the down-level clients and BDCs have been upgraded to Windows 2000, the domain can be switched over to native mode. This is a one-shot operation, which cannot be undone. Once in native mode, the groups can be nested, and universal groups are available. In native mode it is also possible to have Windows NT 4.0 member servers; however, Windows NT 4.0 BDCs are no longer accepted in the domain. It...