After you create a domain, you should create an additional domain controller in the domain to provide fault tolerance and load balancing for Active Directory.

To add a domain controller to an existing domain, run Dcpromo.exe to start the Active Directory Installation wizard. Complete the wizard by using the information in the following table.

On this wizard page Do this
Domain Controller Type Click Additional domain controller for an existing domain.
Network Credentials Specify the user name, password, and domain name of a user account that has rights to create domain controllers in Active Directory.
Additional Domain Controller Specify the DNS name of the existing domain for which this computer will become an additional domain controller.
Database and Log Locations Specify locations for the Active Directory database and log files.
Shared System Volume Specify the location for the shared system volume.

After you finish specifying the installation information, the Active Directory Installation wizard converts the computer to a domain controller, replicates Active Directory from an existing domain controller, converts the computer to a domain controller, and adds the Active Directory consoles to the Administrative Tools menu on that computer.