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.