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.

What is FQDN?

The popular acronym FQDN stands for Fully Qualified Domain Name. It represents the fullest possible domain name of a host or a computer on the internet. In addition, it could be related to a website or to a server. 

As you probably know, the Domain Name System (DNS) is decentralized, and it is built in a very precise hierarchical order. The Root is the beginning and above everything else, and one level below is the Top-Level Domain (TLD). The following component in the hierarchical order is the domain, and finally, the last important element is the precise hostname.

• FQDN Syntax

Here you can see the syntax of it:

[hostname].[domain].[tld]

It can also include a subdomain. Yet, you should know that the subdomain is not the hostname. It is just a part of the domain. 

• FQDN Example

Let’s see an example of FQDN using cloudns.net. We read it from right to left.

www.cloudns.net

First is “.net“, which is the Top-Level Domain (TLD). 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.

Structure and elements of FQDN

The Fully Qualified Domain Name (FQDN) actually has a very simple and easy-to-understand structure and three main elements. So, let’s explain a little bit more about them:

TLD (Top-Level Domain): It is shown with all of the standard extensions that are located at the very end of an FQDN. They usually are very short, and their length is just 2 or 3 letters. Some popular examples are .com, .edu, .uk, etc. Of course, in the present days, you can find TLDs that are a little bit longer than that. For instance, there are .systems, .company, etc.

Domain: It stands exactly after the Top Level Domain (TLD) and is very well-known, and regular users are familiar with it. Here is a simple illustration – example.com.

Hostname: You can also identify it with ease. It is represented by the symbols at the very beginning of the Fully Qualified Domain Name (FQDN). Here a widespread and familiar example is www in www.example.com. Some domain owners could create different hostnames based on the need of their domain name. Each of them is going to be related to the domain. Several examples of such different hostnames are:

• www.example.com
• ftp.example.com
• mail.example.com

What is PQDN?

The short acronym PQDN stands for Partially Qualified Domain Name and it simply represents an FQDN (Fully Qualified Domain Name) with a missing part. It does not include all of the elements that provide the precise position on the DNS hierarchy. It is just a part of the complete domain name. 

To make things more simple, let’s use the ClouDNS domain name again for an illustration. The PQDN is, for example, “cloudns.net“. In this one, we don’t have the host “www.“.

Many users use PQDN daily without even knowing it. The reason for that is simple. PQDN is more accessible and easy to use. In addition, it is shorter, which makes daily searches quicker and easier.

If you are searching for a fast and secure DNS service – the best choice is the Anycast DNS!

How to make a FQDN lookup?

You can perform an FQDN lookup on your computer with any of the popular operating systems (OS).

Windows 10

Here is how to see the FQDN on a Windows 10 device:

1. Click on the Start menu, type “Control Panel,” and click it. 
2. Inside the Control Panel, find “System” and open it. 
3. Inside the System, look for “Device specifications” and search for the “Full Computer Name.” 
4. There is the FQDN. 

macOS 

If you are using macOS, follow these next steps to find the FQDN.

1. Open the Terminal application.
2. Inside, type the following command: “hostname -f” and press the Enter button. The option “-f” means full. 
3. You will see the FQDN. 

Linux 

If you are a Linux user, you can find the FQDN similar to the macOS.

1. Open the Terminal application. 
2. Inside, type the following command: “hostname -A” and press the Enter button.
3. You will see the FQDN. 

Why do you need FQDN?

Here are some of the main cases when FQDN comes in hand:

• 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.

Conclusion

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. 

Tags: domain, domain names, FQDN, fully qualified domain name, pqdn Last modified: February 13, 2023