Domain upgrade scenarios

In a domain upgrade, you convert a Windows NT® domain controller to an Active Directory domain controller. During an upgrade, the primary domain controller is unavailable briefly.

These topics describe several scenarios in which one or more Windows NT domains are upgraded to Active Directory domains by using the in-place upgrade procedure defined by Microsoft. If your site is not using this procedure, see Domain migration scenarios.
Note: References to upgrading a domain refer to upgrading the primary domain controller of that domain.