As important as DNS is to web hosting, it is a good idea to make it redundant when possible. If you have two or more cPanel servers, you can use cPanel’s DNS clustering to lower the risk of a DNS failure on a nameserver taking down all of your sites. Here’s how to set that up:
Step One: Enable Clustering For Each Server
First, click over to Configure Cluster in WHM on each server. In the Modify Cluster Status box, select Enable DNS clustering. Click the Change button.
Step Two: Configure The Primary Nameserver
On the first server, scroll down to Add a new server to the cluster. The type will be cpanel. Click Configure. This will take you to the cPanel DNS Remote Configuration page.
In Remote cPanel & WHM DNS service, put the hostname or IP address of the second nameserver. Next, in Remote server username, put the username of the nameserver. While this can sometimes be reseller, in most cases it will be root.
In the next area, Remote server access hash, you will need to put the ssh public key of the other server. To find that key, go to the Manage root’s SSH Keys page in the second server’s WHM. Click Generate a New Key. On the next page, leave the password blank and click the Generate Key button. cPanel will issue a warning about the security of an SSH key without a password, but unfortunately it is needed for this sort of automation. (It is only a security risk if someone gains root access to your server, by which point your server’s security will already have been compromised.)
Still on the second server, click back to Manage root’s SSH Keys. Then click View/Download Key under the Public Keys: heading. This will take you to the key which you will then copy back to the first server, in the Remote server access hash field.
Uncheck the Setup Reverse Trust Relationship checkbox.
Set the DNS role of the server to Write-only. Click Submit.
Step Three: Repeat Step Two, Only Backwards
Step Three is going through the same process as Step Two, only reversing the servers. Also, role of the server should be set to Standalone instead of Write-Only.
Adding DNS Zones
There is one quirk of this system: DNS zones for domains will have to be added on the Write-Only server. So when creating cPanel accounts on the Standalone server, make sure to add the DNS for the domain to the Write-Only server.