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3/18/2015 – My Server Cannot Resolve Domains—Why Is That?

Posted by Jamison on 18 03 2015.

This is usually due to an invalid nameserver setting in the /etc/resolv.conf file.


  • Contact your datacenter for suggested nameservers within their network.
  • You can also add a valid public nameserver to /etc/resolv.conf.


What is a name server?

According to the cPanel staff, the word nameserver is used interchangeably for both a piece of software that runs on most web servers, and as a setting in every domain’s DNS (Domain Name System) configuration.

As a piece of a domain’s DNS configuration, nameservers are locations where everyone trying to access your website will go to look up your DNS information. It is very important to note that these are defined both at the domain registrar, and in a domain’s zone file, and that they need to match in both places.

As a piece of software, nameserver references the program that serves DNS information in response to queries. On your cPanel server you can choose between three of the most common nameserver software: Bind, MyDNS, and NSD. Each has advantages and disadvantages, which are outlined for you in the WHM interface.

Why are nameservers important?

Accurate and stable nameservers are vital to your site’s function and uptime. A misconfiguration in your DNS information will make your web traffic improperly routed, resulting in downtime. Make sure that everything is set correctly as well as up and running or else you have downtime


If you choose to start with a fresh install, then here’s how to setup personal nameservers in WHM:


You will need:


A Linux server with cPanel installed, and at least two IPs.
An understanding of how to interact with WHM’s interface.
A base understanding of terminal and command-line interfacing.


To set up a personal nameserver, perform the following steps:


  1. Navigate to the Nameservers section of the Basic cPanel & WHM Setup interface (Home >> Server Configuration >> Basic cPanel & WHM Setup)
  2. Add your nameservers in the available text boxes.
  3. Click Assign IP Address next to each nameserver to assign it an IP address.
  4. Click Add an A entry for this nameserver to allow each nameserver to resolve through DNS.
  5. Click Nameserver Selection under Service Configuration to enable the nameservers.


DNS Propagation

All over the internet there are things called caching nameservers. Caching nameservers do not serve as authoritative for any domains. Rather, they cache DNS lookups, to reduce overall internet traffic and decrease load times.

RDNS (Reverse DNS) or PTR records

If DNS records resolve a domain to an IP address, then reverse (or PTR) records are just the opposite of that: resolving an IP address to a domain. Having your RDNS configured correctly is most crucial to email delivery. For example, if a server you’re sending email to requires that the reverse DNS for the sending IP match the SMTP banner, you will want to make sure that the RDNS for all of your sending IPs match your hostname.

You can use the ‘dig’ command to look up the RDNS of an IP address with the ‘-x’ flag. Your command for looking up the hostname’s IP looked like this:


[~]# dig +short @localhost