If all your nameservers point to one server and it goes down, every domain stops resolving, including email. A DNS cluster copies zones from your cPanel servers to other servers, usually dedicated cPanel DNSOnly machines, so DNS stays up when a web server fails.
MdmHost manages these settings on its hosting plans. This guide is for administrators of their own cPanel VPS or dedicated server with root access.
Before you start
- Root access to every server involved.
- At least one extra server for DNS, ideally in another data centre, running cPanel DNSOnly (free) or full cPanel.
- Your nameserver hostnames, for example
ns1.yourbrand.comandns2.yourbrand.com, with glue records at the registrar (see private nameservers).
Create an API token on the remote server
- On the DNS server, log in to WHM as root.
- Go to Development → Manage API Tokens and generate a token with Clustering privileges (or all privileges on a DNSOnly server).
- Copy the token.
Enable clustering on the web server
- On the cPanel web server, go to WHM → Clusters → DNS Cluster.
- Click Enable DNS Clustering and save.
- Under Add a new server to the cluster, choose cPanel as backend type and click Configure.
- Enter the remote hostname,
rootas username and the API token. - Choose the DNS role (below) and submit.
DNS roles
| Role | Behaviour |
|---|---|
| Synchronize changes | Changes on this server are pushed to the remote, and the remote can push back. Typical for DNSOnly servers. |
| Write-only | This server pushes zones to the remote but does not receive changes. |
| Standalone | No synchronisation; used only for lookups. |
Add the reverse link on the DNS server too if you want two-way synchronisation.
Synchronise existing zones
New zones sync automatically. Push existing ones with WHM → DNS Functions → Synchronize DNS Records, choosing Synchronize all zones.
Tip: Point ns1 to one server and ns2 to another, in different networks. That is the whole point of a cluster.
Check the cluster
dig @ns1.yourbrand.com example.com SOA +short
dig @ns2.yourbrand.com example.com SOA +shortBoth should return the same serial. Edits in Zone Manager should appear on every server within seconds.
Troubleshooting
Zones not syncing
Check the remote server is reachable on port 2087 and the token is valid. DNS Cluster shows the status of each link.
"Zone already exists" conflicts
Two servers own the same domain. Remove the stale zone on the server that should not host it.
Frequently asked questions
Is cPanel DNSOnly free?
Yes, cPanel DNSOnly is a free edition meant for DNS cluster nodes.
Can I use a cluster with external DNS providers?
Not with the built-in cluster. For external providers, use their API or secondary DNS (zone transfer) features.
Do resellers need to do anything?
No. Reseller and customer zones are synchronised automatically once the cluster is set up.
How many DNS servers do I need?
Two nameservers on separate servers and networks is the minimum; three gives extra resilience for larger setups.