Introduction
Domain Controller (DC) is a server that responds to authentication and authorization request. When user logs into the domain the DC checks their username, password and other credentials to either allow or deny for that user.
Why need an additional Domain Controller?
Most organizations can work with one domain controller but for a critical environment, the organization needs to have a backup. Additional domain controller provides fault tolerance. They replicate the Active Directory information and the backup server kicks in if the primary server fails.
Prerequisites before installing Active Directory on a secondary server
- Configure static IP address
- Assign computer name
- Change the DNS to your primary server IP address
Ensure your secondary server can communicate with the primary server and ping the primary server. In my case, ping ad1.techyul.com
Step 1: Installing roles and features
Click on Add roles and features from Server Manager
Click Next on this page
Leave the radio button on Role-based or feature-based installation on the installation page and click Next
Select the server to install Active Directory roles. In my case, I am installing it on the local server. Click Next
Check the Active Directory Domain Services box and click Add Features from the pop-up
Click Next after selecting the Active Directory Domain Services
Click Next from Select features page
Click Next again
In this section, you need to review the options and click Install.
Note: Choosing “Restart the destination server automatically if require” is optional
Wait for the installation to complete. It may take a few seconds to a few minutes
Step 2: Promote the server to a domain controller
Click on Promote this server to a domain controller link
Leave the deployment method to Add a domain controller to an existing domain
Click on Change and type your credentials of your primary domain controller, AD1
Type your credentials of the primary server. In my case, it’s AD1 and click OK
It will pull your domain. After confirming your domain click Next
Verify that Domain Name System (DNS) server and Global Catalog (GC) are selected. Type your recovery password and click Next
Ignore the DNS server error and click Next
Select the server where you want to replicate from. In my case, its AD1.techyul.com and click Next
Leave the Paths default and click Next
Review your configuration and click Next
In this step, the server checks all the prerequisites. If the prerequisite pass, click Install
Wait for the installation to complete. It may take a few minutes. The server will reboot after the installation complete
Now sign in as Domain Administrator
Step 3: Verify additional domain controller
Select Active Directory Users and Computers from Tools in Server Manager
Expand domain.local (techyul.com) and select Domain Controllers. You can find both DC here (AD1 and AD2)
Step 4: Change IP addresses
Make your Preferred DNS server IP of your AD2 IP address. Your Alternative DNS server IP should be your primary Domain Controller. In my case, the IP address of AD1
Sign in to your primary domain controller. Your Alternate DNS server IP should be your secondary server IP address. In my case, the IP address of AD2
Conclusion
We need a secondary domain controller for fault tolerance. Your IT team keeps working on recovering the primary domain controller but the organization needs access to important domain resources until your primary server goes live.
Thank you for reading, I hope you like this article please leave a comment if you have any questions.
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