Solution: Remove the domain controller from the domain. To remove a domain controller from a domain, perform the following steps using an AD DS account that has membership in the following AD DS group: Domain Admins; Log on to the domain controller you want to remove from the domain. Click Start, click Run, type dcpromo, and click OK. Before adding a 2012R2 domain controller to the existing 2008 environment, it is mandatory to update the Active Directory schema to windows server 2012. You must update the schema from the domain controller that hosts the schema operations master role (FSMO). In the previous article, we have set up our first Windows Server 2008 Domain Controller in a New Windows Server 2008 R2. In this article, we will install Additional Domain Controller in an existing Windows Server 2008 R2 domain. 1. You must have administrative credentials on the existing Active Directory domain to add an additional domain controller. So on Windows Server 2008 32bit you have to prepare the forest/domain with the new way remote from Windows Server 2012 or Windows server 2012 R2. With the 64bit version from adprep you can still work on Windows Server 2008 64bit and Windows Server 2008 R2 DCs for the Schema update. Select add a Domain Controller into existing to NICs of all machines in the domain then what will be the best course of action when I am adding this additional 2012 R2 domain controller. Thank you very much for this to Torio I actually used it to convert a Windows 2008 server to a 2012. Step 5: Removing the Windows 2008 R2 domain controller On the Windows 2008 R2 server click Start , Click Run, type dcpromo , then click OK. After the Welcome to the Active Directory Installation Wizard page, be sure to leave the Delete the domain because this server is the last domain controller in the domain unchecked. ADUC may prompt you for further confirmation if the domain controller is a Global Catalog or a FSMO role holder. That's all there is to it. If the domain controller ever comes back online, you must either erase the server and reinstall Windows or perform a forced demotion of the domain controller. I have a forest with 2 domains controllers. Windows 2008r2 . Primary and secondary. The secondary domain controller have crashed completely . It is a virtual machine and it has corrupt data. So , any ideas how force remove the secondary domain controller to add a new one ? Thanks I would have thought the best way to do this is introduce a 2008 r2 fully patched server onto the network, promote it to a domain controller, once its a DC and replicating, then you could start to move all the FSMO roles etc over to it. Would this be the way to go? If there are schema updates mind you it may be slightly more tricky. Tarek Majdalani Windows Server & Edge Security Portal. In a previous article, we have set up our first Active Directory Domain Services (AD DS) using Windows Server 2008.In this article, we are going to see how to set