# Guide to DNS Cluster Configurations

https://www.hostcarts.qa/knowledgebase/article/guide-to-dns-cluster-configurations

## Overview

A DNS cluster is a group of nameservers that share records with each other. This allows you to physically separate nameservers that handle the DNS requests from your cPanel & WHM servers.

- WHM’s [*DNS Cluster*](https://docs.cpanel.net/whm/clusters/dns-cluster/) feature (*WHM >> Home >> Clusters >> DNS Cluster*) **only** provides redundancy for DNS. It does **not** add Apache or any other services to a DNS cluster configuration.
- cPanel DNSOnly allows you to run a dedicated physical nameserver. It **only** replicates DNS zones to your other servers. For more information, read our [cPanel DNSOnly](https://docs.cpanel.net/knowledge-base/dnsonly/cpanel-dnsonly) documentation.

### DNS cluster requirements

To configure your DNS cluster, you must meet the following minimum requirements:

- Clusters **must** include at least two servers.
- You **must** have at least one cPanel & WHM server with cPanel & WHM installed. A DNS cluster that includes multiple cPanel DNSOnly™ servers and cPanel & WHM servers is also acceptable.
- All machines in the DNS cluster **must** have cPanel & WHM or cPanel DNSOnly version 11 or higher installed. Some features may not work with older versions of cPanel & WHM.

## DNS cluster structures

Before you set up your DNS cluster, consider which structure will be the most efficient. The way in which you link each server determines the speed at which your DNS requests resolve.

Important:

- We recommend that you do **not** set up the nameserver to synchronize data to a cPanel & WHM server, because this creates extraneous zones on the cPanel & WHM server. This means that you do **not** need to log in to WHM on the nameserver and set the cPanel & WHM server’s *Synchronize Changes* DNS role. For more information about DNS server roles, read our [*DNS Cluster*](https://docs.cpanel.net/whm/clusters/dns-cluster/#servers-in-your-dns-cluster) documentation.
- If you set a server in a DNS cluster to the *Write-only* role, WHM will **not** check whether a DNS zone exists before you create an account. Because of this, it is possible to create the same domain name on two or more of these servers. If this occurs, the servers compete for updates to that domain.
- **Don’t** link dedicated nameservers to each other, or link dedicated cPanel & WHM servers to each other.

### Use direct links

Your servers function more slowly if multiple steps exist between a cPanel & WHM server and a nameserver. To improve the performance of your servers, link your cPanel & WHM server directly to the DNS servers. This eliminates the steps that each request must perform, and your DNS requests will resolve more quickly.

*A direct link between the web server and each of two nameservers is optimal.*

Note:

In this example, `webserver.example.com` sends DNS information directly to `ns1.example.com` and `ns2.example.com`.

To create this configuration, you will need **one** cPanel & WHM server and **one or more** nameservers.

### Use the primary nameserver as an intermediary

If necessary, place the primary nameserver between the cPanel & WHM server and the secondary nameserver. For each intermediate server that you add, data will transfer three times slower than for a direct link.

*An intermediate nameserver between the web server and secondary nameserver is acceptable.*

To create this configuration, you will need **one** cPanel & WHM server and **at least two** nameservers.

### Use multiple intermediary nameservers

Warning:

We do **not** recommend this method. It can significantly reduce performance.

This configuration uses multiple steps between the cPanel & WHM server and nameservers. In the example below, for `web1.example.com` to communicate with `ns2.example.com`, the information **must** pass through two intermediary servers. This increases the processor load on the servers because the nameserver software updates the DNS information on each step. This configuration slows the servers’ response time considerably.

*If you configure multiple steps between a web server and nameserver, the servers’ performance slows.*

To create this configuration, you will need **at least two** cPanel & WHM servers and **at least two** nameservers.