A domain controller (DC) is a server computer that responds to authentication requests. It participates in the replication and contains a complete copy of all directory information for their domain. If your environment requires high availability of IT systems when one DC fails, another takes over to ensure successful login, etc. Please see this guide for how to set up VMs in Hyper in order to have Domain Controllers running on Virtual Machines, and “Post OS configure Windows Server 2019 Properties, and how to Setup and configure a DC. In this article, you will learn how to add a second Domain Controller.

If you wish to install an additional domain controller to balance the load and increase fault tolerance. This how-to guide describes the steps needed to add a domain controller to your existing Active Directory (AD) environment.

Also, see How to add a new Domain Controller to an Existing Domain, How to setup a Third-Party DNS Server on a Linux Server, and how to Setup a Domain Controller as Recommended by Microsoft.

Add a second Domain Controller

Kindly follow the steps discussed below to add an additional DC to your domain. You will have to install the AD DS role and promote it as a Domain Controller.

Add a domain controller into an existing domain

Note: You can decide to join this server to the domain before promoting it as a domain controller.

But in my case, I did not join the second Domain Controller to the domain previously. Because, when adding a new domain controller into an existing domain, this action will be performed by default.

If you previously joined the Server to the Domain before promoting it, it will move the computer object out of the computer OU to the Domain Controller OU (Container) Next click on Change to enter the credential needed to join the domain.

You may encounter an error in this stage if you are using the default administrator account.

Create a new account and add the user as a member of the domain Administrator. This works! Remember to uncheck the Domain Name System Here (DNS) server. We do not need it as there is an existing DNS server.

Please see Fix Outlook Not Responding and Outlook Crashing or freezing, Domain Join: How to join a computer to the Domain, and how to fix “Error: An Active Directory could not be contacted or cannot find domain because it is nonexistent“.

Specify Replication Server

Under Additional Options, select “Replicate from” using the drop-down button to specify the DC to replicate from.

Under paths, you can decide to store them in a different location as best practice. I will leave them as default.

Under the review Option, click on next as this gives you an opportunity to review what you have done.

Here it will perform the prerequisite checks and if it passes, it will prompt you to install Active Directory Domain Services.

After installation, the computer will reboot. Now both DCs are global catalogs and can respond to user queries.

That is all 🙂 Verify the replication from Active Directory Sites and Services. I will be blogging on how to perform manual replication and testing if replication works. Keep an eye on this site for this.

Please see how to fix “The trust relationship between this workstation and the primary domain failed“, how to Integrate TestRail with Cypress, and how to Fix Python was not found run without arguments to install from the Microsoft Store.

I hope you found this blog post helpful on how to add a second Domain Controller. If you have any questions, please let me know in the comment session.