What Is A Fully Qualified Domain Name?

What Is A Fully Qualified Domain Name?

In the landscape of domain names, there’s a lot going on. We have DNS records, top-level domains, second-level domains, sub-domains, and a lot more.

There’s no shortage of confusing terminology that can trip up beginners. Luckily, you don’t need to know all of this to buy a domain name and set up a website. But, still these terms come up and you want to know what they’re all about.

One term you’ll come across is Fully Qualified Domain Name, or FQDN. Below we’ll highlight why knowing your FQDN is useful, what it can be used for, and some examples of what it looks like.

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What Is a Fully Qualified Domain Name?

The term Fully Qualified Domain Name is actually pretty literal. Essentially, it’s the complete domain name of a computer, or host, on the Internet. It’s composed of a few different elements.

Here’s how it breaks down:


In some cases a subdomain can also be included as well. Like any other domain name, we read it from right to left.

For example, here’s how we break down the Fully Qualified Domain Name, www.hostgator.com.The first part (‘www’) is the host name. The second part (‘hostgator’) is the domain name. The last part (‘com’) is the TLD (top-level domain).

The final element of a FQDN is the final period at the end. However, almost every browser doesn’t require you enter this period and it’s instead implied by the system. You can try adding a period yourself to the end of any domain, and you’ll see that it doesn’t alter the path of the domain in any way. Interesting, right?

You can think of a Fully Qualified Domain Name as an address. The goal of this address is to designate the location within the DNS system. With a FQDN the location of a website, or other online entity has its own unique identifier and location.

Below we review a few more examples to help you better understand how a FQDN breaks down.

Examples of a Fully Qualified Domain Name

A fully qualified domain name is always written in a specific format.

If you’re a Gmail user, then you’ve no doubt seen this one, ‘mail.google.com’.

Or, how about this one, ‘en.wikipedia.org’? In this case, the host name is ‘en’, which specifies the English version of the host.

It’s funny, but most domain names aren’t technically fully qualified. For example,  ‘amazon.com’ isn’t technically fully qualified because we’re not 100% sure of the host name, even though most browsers assume the host name is ‘www’.

How Are Fully Qualified Domain Names Used?

If you want to make a website, computer, or any device accessible via an Internet network, then you’re going to need an FQDN. However, you’ll also need to interface with the DNS records, so the location of that device, or website, can be found.

FQDNs are one of the most essential components of how the Internet and domains are organized. For that reason they have a wide variety of applications, that extend beyond letting your website or device be available to the Internet.

But, beyond that one of the most common reasons you’ll need to know your FQDN is for obtaining an SSL certificate.

Today, especially with the recent Google shift, an SSL certificate is becoming a necessity. To actually obtain an SSL certificate and secure your site you’re going to need a Fully Qualified Domain Name.

Also, if you’re connecting to your host remotely, then you’ll most likely need your FQDN to remotely connect. For example, if you’re connecting over FTP then you’ll need the FQDN or the IP address to access the server.

How Do You Find Your Fully Qualified Domain Name?

Locating your FQDN address for your website is easy: just look at the address bar in your browser. You’re probably amazed at the frequency you’ve been interacting with Fully Qualified Domain Names, without even realizing it!

But, beyond a website’s domain, both your computer and server have their own unique FQDN as well.

Here’s how you locate your machine’s FQDN:

  • For Mac users: Open up Terminal and type in ‘hostname –f’. This will return your FQDN.
  • For Windows users: You can find your FQDN within your system settings. First navigate to your ‘Control Panel’ and locate ‘System and Security’. From here select ‘System’ and you’ll find your FQDN listed on this screen.

What is a Partially Qualified Domain Name?

Another term you might have come across is PQDN, or a Partially Qualified Domain Name. This is similar to a FQDN, but the domain isn’t fully specified. Typically, this will refer to a portion of the domain name, but you won’t have every detail to specify it completely.

This was mentioned briefly above in the example ‘amazon.com’. Although the web host will guess the ‘www.’ aspect, it still isn’t fully specified.

Typically, a PQDN is used for convenience in very specified contexts, like leaving out the ‘www’ portion.

But, it’s important to understand that a FQDN and PQDN aren’t the same thing. With a FQDN you have the entire path of the host, but with a PQDN you only have a small-specified portion that works within a specific context, because the additional host details are contained within the system. Like a web browser intuiting the ‘www’ portion of a web address.

Have You Located Your FQDN?

Hopefully, you have a better understanding of what a Fully Qualified Domain Name is and the instances in which they’re used. When you create a domain name, or transfer it to a new host, you’ll want to know how a FQDN works in the bigger picture.  

Kevin Wood writes about technology and human potential. You can find him at his virtual homes Wooden Writing and Counter Culturist.