Add a Domain Controller to an existing domain in Windows Server 2016

It is always good proactice to have at least two domain controllers in your Active Directory Domain just in case one goes down. The procedure for adding a domain controller to an existing domain is the same regardless of which Windows Server you have.

This post assumes that your second server is running Windows Server 2016 and is fully patched.

  1. Open Server Manager, then click the Manage option and select Add Roles and Features.
  2. In the wizard, click Next.
  3. In Installation Type select Role-based or feature-based installation radio button and click Next.
  4. In Server Selection leave the only server in the list highlighted and press Next.
  5. In Server Roles check the Active Directory Domain Services box. A dialogue box appears. Click Add Features button.
  6. Back in the main feature screen, click Next. This cycles through to the Features screen. Click Next.
  7. In the AD DS screen, click Next.
  8. Finally, click Install
  9. Once the installation process finishes, you will see a notice telling you that additional steps are required. Click Promote this server to a domain controller to continue.
  10. Leave the Add a domain controller to an existing domain radio button active.
  11. At the bottom of the list of options, you will see <no credentials provided> Click Change.
  12. Enter the username and password of the Administrator account on the AD instance that you first set up. The username should be in the format <domain>\Administrator. Click OK.
  13. You'll now see the Domain field has been populated with the domain that you entered for the user account. Click Next.
  14. Now decide if to make this a read-only domain controller (RODC). If so, check that box in the Options screen, if not, check both the DNS server and Global Catalogue boxes.
  15. Enter a DSRM password and confirm it. Click Next. You'll be shown a warning, just click Next to continue.
  16. In Additional Options choose your original domain controller for the Replicate from field. Click Next.
  17. Leave all of the paths in their default settings, click Next. In Review Options, click Next.
  18. The system will perform a prerequisites check. If that completes satisfactorily, the Install button will become active. Click Install.
  19. Wait for the installation to complete. The computer will reboot.
  20. (optionally) Go back to your original domain controller computer and open Active Directory Users and Computers and you will see that your new DC is listed in the Domain Controllers folder.