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.