How to promote Windows Server 2008 to Domain Controller and Join an Existing Domain
1. Click Start > Run > type DCPROMO and click OK
2. Click Next
3. Click Next
4. Select Existing Forest and Add a domain controller to an existing domain then click Next
NOTE: If the server you are promoting is going to be the first domain controller, select Create a new domain in a new forest.
NOTE: If the server you are promoting is going to be the first domain controller, select Create a new domain in a new forest.
5. Type the name of the domain in the forest where you plan to install this domain controller then click Next
6. Click Next
7. Wait
8. Click Next
9. Check Global Catelog checkbox if you want the server to be a global catelog server. Click Next
10. Select Transfer the infrastructure master role to this domain controller.
11. Wait
12. Click Yes
13. Go with the default location for the database and click Next
14. Create the Restore Mode Administrator Password and click Next
15. Verify the information in the summary and click Next
16. Wait for the wizard to configure Active Directory Domain Service
17. Click Finish