This post will show the proper use of ADPREP and what to expect when you are running it. ADPREP is broken down into four stages with Windows Server 2008, instead of the two that most of you may be familiar with when you upgraded to Windows Server 2003. The four steps include Forest Preparation, Domain Preparation, Group Policy Preparation and Read-Only Domain Controller (RODC) Preparation (which you have to run if you want to add a RODC to your environment). You will use ADPREP.exe to perform all of these steps.

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