This is a topic that often confused me when I first began experimenting with web and email server configuration. So, here is an insanely quick guide to the fully qualified domain name (FQDN):

A FQDN uniquely identifies a single device using DNS. Where the domain zone "" may refer to any number of frontend web servers, "" would refer to the server named "phantom" on the domain. FQDNs are important because they unambiguously point to a single server by name. Web and (especially) email servers often rely heavily on a properly-configured FQDN.

Ensure you've:

  1. Given your server a hostname
  2. Configured an A and/or AAAA DNS records that points to the server's IP address (replace "phantom" and "" with your information, of course!)
  3. Configured your server's /etc/hosts file to reflect the FQDN:
IP address     FQDN                    server's name     phantom

That's FQDN in a nutshell! Not too bad, right?

This written work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

blog comments powered by Disqus