3.9. Planning for Upgrades in an Existing Forest
Most of the time, whenever you are trying to upgrade a server farm from one version of Windows to another, you're trying to upgrade within the same forest and more than likely within the same domain. Accordingly, you first have to remember the basic and essential commands to upgrade a domain controller, prep a domain, prep a forest, and prep an environment for a Windows Server 2008 read-only domain controller (RODC). In the following sections, you will examine these processes one at a time, beginning with the forest-level and domain-level prep commands.
3.9.1. Forest and Domain Preparation
Both adprep /forestprep and adprep /domainprep require you to be logged in as an enterprise administrator. ...