FQDN Definition: What is a Fully Qualified Domain Name?

When discussing domain names, you may hear the phrase fully qualified domain name (FQDN) a few times. However, do you (really) know what it means or what it’s used for?

The FQDN definition is confusing if you’re unfamiliar with technology and software terminology. That’s why we’ve created an easy-to-follow guide where we’ll cover everything you need to know about FQDNs:

Let’s get started!

What is a fully qualified domain name?

An FQDN provides the necessary attributes to identify a website’s location online. It’s a complete domain name that includes the hostname, the domain, and the top-level domain (TLD).

Before explaining the FQDN structure in-depth, let’s clarify what a domain name is.

A domain name is simply the text people type in a web browser to visit a website. If you want to go to YouTube, you’ll write youtube.com in your browser, right? Well, that’s YouTube’s domain name.

Youtube’s FQDN would be www.youtube.com. This domain name identifies and locates precisely the website in the internet framework. It provides the exact location of an object (in this case, a website) within the Domain Name System (DNS).

The DNS is known as the phonebook of the internet. Whenever you type a domain name in your browser, the DNS translates words (youtube.com) into a complex IP address (e.g., 208.65.153.253).

Your computer 💻 understands this numerical code and takes you to the right website or the online content you’re looking for.

The structure of an FQDN

An FQDN divides into the:

Hostname: the FQDN hostname specifies the services, protocols, or subdomains of a website. The conventional hostname for your site is www. You’ll use the prefix mail. if you want to host an email service on your website. E.g., mail.mywebsite or www.mywebsite.
Domain: the domain is your site’s address name. It’s located between the hostname and the TLD. E.g., mywebsite.
Top Level Domain (TLD): the TLD is the last segment of a domain name. E.g., .com or .org.
Trailing period: although you don’t need to write a period after typing a URL in a web browser, an FQDN should end with a trailing period to indicate that the previous string is the TLD. E.g., www.mywebsite.com.

As explained above, these are all valid FQDNs:

www.mywebsite.com
www.mywebsite.org
mail.mywebsite.com
mail.mywebsite.org

A Fully Qualified Domain Name is much more reliable than an IP address because it specifies an organization’s entire domain name hierarchy, which helps prevent DNS name resolution issues.

FQDN examples

Now that you know what a Fully Qualified Domain Name is and its structure, it’s time to look at some examples.

See this FQDN example of a jewelry business website: www.diamondsjewelry.co.

It includes a:

Hostname: www.
Domain: diamondsjewelry.
TLD: .co.
Trailing period.

Find below a list of FQDNs generated with the domain name generator DomainWheel.

www.mybusinesses.blog
www.myonlinecocenter.com
www.myhomebusiness.info
www.companycenter.info
www.companytech.org
www.onlineatelierlive.org
www.onlinemarket.blog
www.onlinemart.blog
www.onlinestoredesign.net
www.onlinestorehome.net

What is a partially qualified domain name (PQDN)?

A partially qualified domain name or PQDN only specifies the domain name of a website address, without the hostname.

Let’s take DomainWheel as an example:

https://www.domainwheel.com/ is the DomainWheel URL.
www.domainwheel.com is the DomainWheel FQDN.
domainwheel.com is the DomainWheel PQDN.

To visit this site, you must type domainwheel.com in a web browser. This is a PQDN, though it is more commonly referred to as a company domain name.

So, can you access a website only by writing a PQDN? Absolutely. Generally, programmers and website engineers design sites so users can see the content they’re looking for regardless of whether they type an FQDN or a PQDN in the browser’s search bar.

PQDN vs. FQDN

The main difference between a Partially Qualified Domain Name and a Fully Qualified Domain Name is that PQDNs are shorter than FQDNs. It requires fewer characters to represent the entire domain name in a URL.

PQDNs are:

Easier to type than FQDNs
Catchier than FQDNs
More memorable than FQDNs

However, there are certain situations where you need an FQDN for your site. Read on to discover why having an FQDN for your website is essential.

Do I need an FQDN for my website?

When you create a website, 🎨 you must choose an available domain name that fits your brand and marketing strategy.

But what about a Fully Qualified Domain Name? Do you need one? If so, where can you find it?

If you’ve read this far, you should know the answer to these questions: you need an FQDN to make your website accessible to users. If your site is visible online, you already have an FQDN.

To find your website’s FQDN, check the address bar in your browser. Generally, you’ll see a PQDN, like example.com. Add the hostname to that domain (www. for websites), and you’ll discover your FQDN: www.example.com.

Having an FQDN is crucial to complete several processes on your website.

Here are two key benefits of using an FQDN for your site:

An FQDN facilitates access to separate resources

If you run an online business, you may want to use the same domain name for your website content and other resources. For example, an email server or a mobile app.

Let’s say you own a photography company called Photography Home. Your domain name is photographyhome.org:

Your site’s FQDN is www.photographyhome.org. By typing this, your customers can access your homepage.
They can access your mail server at mail.photographyhome.org.
And they can access your mobile app at app.photographyhome.org.

If you use separate Fully Qualified Domain Names for different resources, your customers can visit your site’s email server or app without going to the homepage. Just by adding the word mail. or app. as a sub-domain (instead of www.), you’ll redirect users to the page they expect to see.

It’s all about making customers’ life easier! 😎

An FQDN is vital for obtaining SSL certificates

Security Socket Layers (SSL) certificates 🔒️ are necessary for online businesses, especially if they need to transmit sensitive data. They secure websites and protect users against unauthorized access.

The only way to get SSL certificates is to have a Fully Qualified Domain Name, given that SSL certificates are assigned to FQDNs.

SSL certificates aren’t only beneficial for security reasons but also help with improving site speed and SEO.

Final thoughts 🏁

FQDN is one of many acronyms used when talking about domain names. It’s just another way to refer to a domain name that includes every piece of information about it.

👉 The structure of a Fully Qualified Domain Name is as follows:

Hostname
Domain name
TLD
Trailing period

Although you don’t need a Fully Qualified Domain Name to find a website online, this domain name is important in some scenarios. For instance, to facilitate access to different resources for your customers and to obtain SSL certificates.

The good news is that you don’t need to do anything special to get a Fully Qualified Domain Name. All you need to do is buy web hosting with a domain name and your web host will make sure your FQDN is fully set up.

Want to find the perfect name for your website? Check out our guide to choosing a domain name and then take a look at our roundup of the best domain name registrars to lock in your selection!