DNS Cluster v86

Valid for versions 86 through the latest version

Version:

82

84

86


Overview

A DNS cluster is a group of nameservers that share records, which allows you to physically separate nameservers that handle the DNS requests from your web servers. This interface allows you to configure a DNS cluster and add servers to an existing DNS cluster.

Note:

For more information about the types of DNS cluster configuration and why you may wish to use a DNS cluster, read our Guide to DNS Cluster Configurations 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 web 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.
Note:
  • WHM’s DNS Cluster feature only provides redundancy for DNS. It does not add Apache or any other services to a DNS cluster configuration.
  • 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.
  • cPanel DNSOnly software allows you to run a dedicated physical nameserver. It is essentially the “bare-bones” version of cPanel & WHM, which only replicates DNS zones to your other servers. Only install cPanel DNSOnly on nameservers that have no previous content on them. You can download the cPanel DNSOnly software for free.

DNSSEC

cPanel & WHM supports DNS Security Extensions (DNSSEC) in DNS clusters. PowerDNS servers with domains that have DNSSEC configured can configure DNS clusters. For more information about DNSSEC, read our How to Use cPanel’s PowerDNS and Zone Editor documentation.

Warning:

All servers in the DNS cluster must run PowerDNS if domains that use DNSSEC exist in that cluster.

DNS Clustering

To modify DNS cluster settings, select whether to manage your DNS clusters as the root user or as a reseller from the Managing DNS Cluster as: menu.

Important:
  • Users must possess the DNS Clustering Account Creation Limit (ACL) privilege to view the DNS Clustering section of this interface.
  • Users who possess the All ACL privilege can add their own custom DNS servers to a cluster.
    • Users with this ACL can also make changes to existing cluster members.
    • Before adding custom DNS servers or changing existing cluster members, select the root option from the Managing DNS Cluster as: menu.
  • For more information about these ACLs, read our Edit Reseller Nameservers and Privileges documentation.

Modify Cluster Status

To enable or disable DNS clustering in WHM, perform the following steps:

  1. Select the desired option under the Global DNS Cluster Options heading:
    • Select Enable DNS clustering to enable DNS clusters.
    • Select Disable DNS clustering to disable DNS clusters.
  2. Click Change. A confirmation message will appear.
  3. Click Return to Cluster Status.
Important:

After you enable the DNS Cluster feature, specify which servers you wish to include in the DNS cluster.

  • You must sync each web server to its DNS servers.
  • You do not need to link dedicated DNS servers to each other, or link dedicated web servers to each other.

Global Cluster Options

The Failure threshold for cluster members setting allows you to specify the number of dnsadmin commands that may fail before WHM disables an unresponsive DNS cluster member.

Note:
  • We recommend that you disable unresponsive DNS cluster members in order to improve the performance of your server.
  • You must enable DNS clustering in order to view the Global Cluster Options section of this interface.

To configure the Failure threshold for cluster members setting, perform the following steps:

  1. Select an option from the Global Cluster Options section:
    • Select 10 (Default) to use the default option, which allows cluster members to fail up to ten dnsadmin commands.
      Note:

      We recommend that you use this option.

    • Select the second option to enter a custom failure threshold.
      Note:

      If server down times or network interruptions are common in your hosting environment, we recommend that you increase the failure number count so that the system does not mark certain cluster members as offline. This may also increase server and network load because the system may repeatedly send some DNS requests.

    • Select Keep all cluster members online at all times if you wish to keep all of the servers in your DNS cluster continuously online, regardless of the number of failed dnsadmin commands.
  2. If you wish for WHM to notify you when it disables an unresponsive member in your DNS cluster, select Receive a notification when WHM disables an unresponsive cluster member.
    Important:
    You must manually reenable a disabled cluster member.
  3. Click Change. A confirmation message will display.
  4. Click Return to Cluster Status.
Important:

If a cluster member in the sync role is offline for an extended period of time, resynchronize the other server’s zones. This ensures that the cluster member is up-to-date.

Unique DNS Clustering

Warning:

This option only appears if you manage your DNS cluster as a reseller user.

By default, WHM uses the DNS servers that reside in the root user or root-enabled reseller’s cluster. To add a different DNS server to the cluster, enable this option.

  • To enable this option, click Enable unique DNS clustering for accounts owned by username.
  • To enable this option, click Disable unique DNS clustering for accounts owned by username.
Note:
  • username represents the reseller user.
  • Resellers can only change a DNS server’s role to Synchronize or Write-only if the root user adds that server to the DNS cluster.

Servers in your DNS cluster

This section allows you to view, add, and delete servers from your DNS cluster.

The Servers in your DNS cluster table displays the following information about each server in your DNS cluster:

Column Description
Hostname The server’s hostname.
IP address The server’s IP address.
Username The WHM username that you used when you configured this server in the DNS cluster. Typically, this is either root or the username of a reseller account.
Type The type of server: cPanel, SoftLayer, or VPS.NET.
Status The version of cPanel & WHM that the server currently runs, and an icon that indicates the server’s status.
  • If your server doesn’t run PowerDNS, this column displays a warning message instead of the cPanel & WHM version. This message notifies you that you must update your server to use PowerDNS if you wish to use DNSSEC clustering. To update your server to use PowerDNS, click the Upgrade link.
Server Type The server’s nameserver software.
DNS role The server’s DNS role. You can choose from the following options:
  • Standalone — This method fetches DNS records from the remote server, but does not write records from the local server to the remote server.
  • Synchronize — This method synchronizes records between the local server and the remote server. Most administrators use this setting.
  • Write-only — This method pushes the local server’s records to write to the remote server, but does not query records from the remote server to write to the local server.
Important:
A Write-only server pushes records to the remote server without conflict resolution or checks. Two Write-only servers that attempt to write changes to a matching record on the same remote DNS server will cause a conflict and may corrupt data.
You can use the menu in this column to change a server’s DNS role.
Actions You can use the icons in this column to modify a DNS cluster server or to delete a server from the DNS cluster.

Add a new server to the cluster

To add a a cPanel & WHM or cPanel DNSOnly server to the DNS cluster, perform the following steps:

  1. Select the server type from the Backend Type menu.

    Note:

    To enable DNS clustering with SoftLayer or VPS.NET, you must first obtain an API username and key from VPS.net or SoftLayer. Then, choose SoftLayer or VPS.NET from the Type menu.

  2. Click Configure. The cPanel DNS Remote Configuration interface will appear.

  3. Enter the hostname or IP address of the nameserver that you wish to link in the Remote cPanel & WHM DNS host text box.

  4. Enter the WHM username for the nameserver in the Remote server username text box.

  5. Enter the nameserver’s API token hash or remote access key in the Remote server access hash text box.

    • Enter an API token hash that you saved on your workstation or create a new API token in WHM’s Manage API Tokens interface (WHM >> Home >> Development >> Manage API Tokens).
      Warning:

      Make certain that after you create an API token, you save the token hash to a safe location on your workstation so that you can use it with other features. The API Tokens table in WHM’s Manage API Tokens interface only displays the API tokens’ names, rather than the tokens’ hashes.

    • You can find the server’s remote access key in WHM’s Remote Access Key interface (WHM >> Home >> Clusters >> Remote Access Key).
      Note:

      We deprecated WHM’s Remote Access Key feature in cPanel & WHM version 64. We strongly recommend that you use API tokens instead.

  6. Select Setup Reverse Trust Relationship for WHM to automatically configure the DNS cluster on the remote server.

    Note:

    If you select this option, you will not need to log in to WHM’s DNS Cluster interface on the remote server. However, you may do so if you wish to modify the remote server’s DNS cluster configuration.

  7. Select Synchronize Zones Immediately if you want to synchronize the new server with the other nameservers in your cluster.

  8. Select Debug mode if you want WHM to record DNS clustering transactions in the /usr/local/cpanel/logs/error_log file.

  9. Select an option from the DNS Role menu to specify the server’s DNS role.

  10. Click Submit to save your settings. When you return to the DNS Cluster interface, the remote server will appear in the Servers in your DNS Cluster table.

  11. Use WHM’s Synchronize DNS Records interface (WHM >> Home >> DNS Functions >> Synchronize DNS Records) to manually synchronize the new DNS server with the DNS cluster.

    Important:

    We recommend that you do not set up the nameserver to synchronize data to a web server, because this creates extraneous zones on the web server. This means that you do not need to log in to WHM on the nameserver and set the web server’s DNS role to Synchronize changes.

Test the clustered server

To confirm that the new server exists in the cluster, perform the following steps:

  1. Log in to your server via SSH.
  2. Run the following command, where example.com represents the server name and ip represents the server’s IP address:
dig +short example.com @ip

Delete a server from a DNS cluster

Important:
  • You must delete a server from a DNS zone before you add a replacement server to the DNS cluster. You cannot have two servers with the same hostname in a DNS cluster.
  • If you remove a server from a DNS cluster, the records will no longer synchronize with the other servers in the DNS cluster. The records on the deleted server will also no longer exist on the servers that remain in the DNS cluster.

To remove a cPanel & WHM or cPanel DNSOnly server from a DNS cluster, perform the following steps:

  1. Log in to the server that you wish to remove from the DNS cluster.
  2. Navigate to the DNS Cluster interface.
  3. In the Modify Cluster Status text box, select Disable DNS Clustering.
  4. Click Change.
  5. Click Return to Cluster Status.
  6. Log in to the servers that remain in the cluster.
  7. Navigate to the DNS Cluster interface (WHM >> Home >> Clusters >> DNS Cluster).
  8. Locate the server that you wish to delete.
  9. Click the x icon () under the Actions heading.

When you return to the DNS Cluster interface, the server will no longer appear in the list of servers in the DNS cluster.

Edit a server in a DNS Cluster

You can change a server’s DNS role or edit the server’s configuration settings at any time.

To edit a server’s DNS role, perform the following steps:

  1. Locate the server that you wish to edit.
  2. In the DNS Role menu, select a new role for the server.
  3. Click the save icon () to save your changes.

To edit a server’s configuration settings, perform the following steps:

  1. Locate the server you wish to edit.
  2. Click the edit icon () under the Actions heading. The cPanel DNS Remote Configuration interface will appear.
  3. After you make your changes to the server’s settings, click Submit.

Additional Documentation