In an environment with many people relying on server access you never want down time because of a hardware failure. To help ensure your Domain Controller is always accessible, you’ll need at least two or more Domain Controllers. This is true with other services too as you don’t want a hardware failure taking out DHCP, Exchange or file servers. I’ll show you here how to add additional Domain Controllers to your network.

In this guide I’ll be presuming you’ve got a fresh Server 2016 install, have a Static IP and have added it to the domain. If you’ve added your Server to Server Manager, you will be able to do all of this remotely by going All Servers, Right click on your server and go Add Roles and Features.

Additional Domain Controllers Setup

On the Server you want to add, open Server Manager and click on Add roles and features.

1. Click Next until you’re on Server Roles and tick Active Directory Domain Services
   
2. Click Add Features on the box that pops up
3. Now, Click Next until you’re on the Confirmation page then click Install.
   
4. After it’s complete, click on Promote this server to a domain controller.
   

The Active Directory Domain Services Configuration Wizard will pop up, follow these steps.

1. Make sure Add a domain controller to an existing domain is checked and that the domain name is correct. Click Next.
2. Type in your DSRM password and click Next.
3. Ignore the DNS Delegation Warning, click Next until you’re on the Prerequisites Check page and then click Install.

The server will restart after a minute and you’ll have a second Domain Controller now up and running. You can shut down your old Domain Controller and try to log in to a client computer to test if the new Domain Controller is working (Remember, DHCP is still only running on the old Domain Controller).