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cPanel multi-server cluster Print

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Many see cPanel multi server (aka cPanel cluster) as a way to prevent business downtime. The logic goes that even if one server fails, the other servers can keep websites and mail online. But, how true is that?


cPanel multi-server cluster – Do you need it?


As of version 11.56, cPanel offers DNS Cluster for DNS high availability and Configuration Cluster for easier server management. If you already have cPanel servers, here’s how cPanel clusters can help you:


1. DNS cluster – How we configure them to prevent service downtime


cPanel creates 2 name servers for each website created in a server (say, ns1.website.com and ns2.website.com). By default, both these two name servers are created in the same physical machine.


This poses a couple of issues:

  • In the event of a server crash, DNS will stop working. This brings down both website and mail – even if the mail is hosted elsewhere (like Google Apps).
  • If a website needs to be moved to another server due to resource constraints or other reasons, the name servers need to be changed, leading to extensive downtime.


A single website downtime can affect your customer’s business. We help web hosts deliver quick resolution to these issues using our 24/7 US based phone support. Learn More.


To prevent such downtime, we setup central DNS clusters for our customers. The DNS of all websites would be hosted in 2 or more dedicated DNS servers.


This way every website will have the same set of name servers (eg., ns1.webhostingcompany.com, ns2.webhostingcompany.com), and even if one server fails, other servers will ensure that the services are up.


With these DNS clusters, we’ve been able to:

  • Prevent mail bounces using a secondary MX entry for domains, that routes mails to a backup mail server.
  • Avoid web or mail downtime during website migrations to other servers. Since name servers are the same for all domains, there’s no need for complex DNS changes and prevents associated downtime.
  • Reduce customer complaints and support tickets that happen during domain migrations.


Many of the name server clusters we’ve implemented were based on open source BIND servers. cPanel has a similar solution called DNSONLY. With this, cPanel servers can be setup to store DNS records in a remote DNSONLY cluster.


2. Configuration clusters – How we use them to simplify server updates


New security threats emerge every day. Servers should be patched and updated frequently to prevent security issues. When you have multiple servers, logging into each of them and running updates can get pretty tiring, and it’s easy to miss updates.


In our role as Server Specialists for small to large web hosting companies, our engineers monitor all security alerts, keep track of server updates, test them for software conflicts, and apply them as soon as possible.


While manual updates minimize chances of error, there are a few situations where we perform mass server updates:

  • When widespread hacks are reported via a web app or system vulnerability, patches need to be applied ASAP. There isn’t enough time to login to each server and manually do the updates.
  • High priority security channel patches are best applied automatically as they do not conflict with functions.
  • Anti-malware, anti-spam and firewall databases need to be updated as soon as they are available, so as to minimize security issues.

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