What is FQDN? What does FQDN do?

FQDN, another hard-to-pronounce abbreviation. You don’t really need to know it to get a domain and set it up, but for the more curious of you, here it is.


FQDN means Fully Qualified Domain Name. It is the fullest possible domain name of a host or a computer, on the internet. Here you can see the syntax of it:


It can also include a subdomain. The subdomain is not the hostname. It is just a part of the domain. 

Let’s see an example with Cloudns.net. We read it from right to left.


First is “.net”, which is the top-level domain. Then it follows the domain name “cloudns”, and the last is the hostname “www.”. 

The hostname can show a specific service or protocol for the domain like “mail” or “ftp”.

The FQDN serves to show the exact location of an object inside the DNS hierarchy.


PQDN is Partially Qualified Domain Name. It is just a part of the complete domain name. Let’s use our domain name again. The PQDN is, for example, “cloudns.net”. In this one, we don’t have the host “www.”.

How to make a FQDN lookup?

You can perform a FQDN lookup on your computer with any of the popular OS.

Windows 10. Go to “control panel” and click “system.” You will see it next to the “Full Computer Name.”

MacOS – Open the terminal, type “hostname –f”, and then press the enter button. You will see the FQDN.

Linux – similar to the MacOS, open the terminal, but this time type “hostname –A”.

Why do you need FQDN?

You will need FQDN to make a device accessible on the internet. You will use it to configure your DNS and get an IP address.

Another use case is when you want to get an SSL certificate. Today, almost every site has one, and you need to provide the FQDN to obtain it.

Remote Access. The DNS server will perform a lookup in its registers and resolve the FQDN to the correspondent IP address.

Access a protocol or a service. If you want to use a FTP for example, you will need the Fully Qualified Domain Name or IP. Also, for setting up email for specific applications, you will need it.


Fully Qualified Domain Name is used all the time, even if you don’t see it directly. It is the full identifier of the domain names.