1. Overview
A DNS cluster is a group of authoritative nameservers that share DNS records with each other. This allows DNS services to be separated from your cPanel & WHM servers, improving redundancy and performance.
WHM’s DNS Cluster feature (WHM » Home » Clusters » DNS Cluster) provides DNS redundancy only. It does not replicate Apache or other services.
cPanel DNSOnly® allows you to run dedicated nameservers that replicate DNS zones across your servers.
Before using this guide, you must have already configured nameservers.
2. DNS Cluster Requirements
- A minimum of two servers is required.
- At least one server must run cPanel & WHM.
- All servers must run cPanel & WHM or DNSOnly version 11 or later.
3. DNS Cluster Structures
The structure you choose affects DNS resolution speed and reliability.
Important: Do not configure a nameserver to synchronize data back to a cPanel & WHM server. This creates unnecessary DNS zones.
Warning: Servers set to the Write-only role do not check for existing DNS zones. This may result in duplicate domains across servers.
Recommendation: Do not link dedicated nameservers to each other, and do not link cPanel & WHM servers to each other.
4. Add Trusted IP Addresses
The file /etc/ips.dnsmaster contains the list of trusted nameserver IPs. If a nameserver’s IP is not listed, users may encounter issues when creating addon or parked domains.
To add additional trusted IPs, use:
WHM » Home » IP Functions » Configure Remote Service IPsor manually add them to /etc/ips.remotedns.
Note: Remote DNS servers must be added manually.
5. Use Direct Links
For best performance, link your cPanel & WHM server directly to each nameserver. This reduces the number of steps required for DNS updates and speeds up resolution.
To create this structure, you need one cPanel & WHM server and one or more nameservers.
Note: When adding a nameserver, you must log in to that server and obtain an API token.
6. Use the Primary Nameserver as an Intermediary
If necessary, you may place the primary nameserver between the cPanel & WHM server and the secondary nameserver. Each intermediary slows data transfer by a factor of three.
To create this structure, you need one cPanel & WHM server and at least two nameservers.
7. Use Multiple Intermediary Nameservers (Not Recommended)
Warning: This configuration significantly reduces performance.
Multiple intermediary servers increase processor load and slow DNS updates.
To create this structure, you need at least two cPanel & WHM servers and at least two nameservers.
8. Reverse Trust Relationship
A Reverse Trust relationship must be established between each server in the DNS cluster. This allows servers to securely share DNS records.
Each server must have an API token.
Configure Reverse Trust in:
WHM » Home » Clusters » DNS ClusterCreate API tokens in:
WHM » Home » Development » Manage API TokensTo verify trust between servers, use WHM API 1’s cluster_member_has_trust_with function.
Note: Use the DNS Clustering ACL privilege when creating API tokens.
Note: DNSOnly servers and servers using the Write-only role do not require Reverse Trust.
9. Conclusion
A properly configured DNS cluster improves redundancy, performance, and reliability. By choosing the right structure, adding trusted IPs, using direct links, and establishing Reverse Trust relationships, you can build a secure and efficient DNS infrastructure for your cPanel & WHM environment.