FQDN (Fully Qualified Domain Name): What It Is, Examples, and More

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A fully qualified domain name (FQDN) is a part of the uniform resource locator (URL). As the name suggests, it is the full name of an entity in the internet framework, including a host and a computer.

This article will explain the fully qualified domain name’s definition, examples, and functions. Then, we will walk you through how to find an FQDN on the three most commonly used operating systems – Windows, macOS, and Linux.

A fully-qualified domain name (FQDN) is a complete domain name that specifies the exact location of a computer or a host on the internet. It consists of the hostname and domain name.

Examples of an FQDN

A fully qualified domain name, also known as an absolute domain name, specifies all domain levels written in the hostname.domain.tld format. For example, a mail server of yahoo.com would be mail.yahoo.com. Other examples include www.wordpress.org and news.bbc.co.uk.

The structure of a fully qualified domain name (FQDN), consisting of the protocol, subdomain, domain name, and top-level domain

Let’s explore each element on an FQDN hierarchy:

  • Hostname. It is a label assigned to a server service available on a network. A DNS server uses a hostname to make an IP address easy to remember. Examples of a hostname are “www” in www.hostinger.com and “en” in en.wikipedia.org.
  • Subdomain. This part is located on the left side of a second-level domain and sometimes indicates a section of a larger domain. For instance, support.hostinger.com is a part of hostinger.com, and the word “support” is the subdomain. Note that not all domains have this element.
  • A domain name. It consists of a second-level and a top-level (TLD) domain. For example, in hostinger.com, “hostinger” is the second-level domain, and “.com” is the TLD.

The maximum hostname and fully qualified domain name length is 63 bytes per label and 255 bytes per FQDN.

Important! Fully qualified domain names need a final dot or a trailing period at the right end to indicate the end of the name, such as www.hostinger.com. However, web browsers today usually assume there is a dot already and ensure you always have an FQDN.

What Is a Partially Qualified Domain Name?

Like an FQDN, a partially qualified domain name (PQDN) also indicates a web address but only includes a hostname or a domain name.

Generally, website developers configure their sites’ DNS to redirect visitors to the same page whether they type the FQDN or PQDN.

For example, if you type hostinger.com or www.hostinger.com, you will land on https://hostinger.com – the URL for our homepage. PQDNs are usually favorable since they are shorter, helping visitors find the site easier.

When to Use an FQDN

FQDNs are usually used in any interaction on the internet as they are easier to remember than IP addresses. Below are several scenarios of when to use an FQDN:

  • Getting an SSL certificate. A secure sockets layer (SSL) protects a connection between a web server and a browser. An SSL certificate is issued to an FQDN, so you may not be able to use SSL services properly without it.
  • Connecting to a remote host. You can make a remote host or a virtual machine by specifying any FQDN, enabling the DNS to look at its DNS table and locate the server. If you use only the hostname to connect to a server, your application may not be able to resolve the hostname.
  • Accessing a specific domain service or protocol. Activities transferring information across a network generally involve the DNS, including pointing to an FQDN. An example is when you connect to a File Transfer Protocol (FTP) or an email server.
  • Migrating to a new server. If you want to migrate your service to a server with a different IP address, using an FQDN instead of an IP address lets you quickly change the DNS record and reduce outages in the IP address changes.

Where to Find an FQDN

Follow the steps below to find an FQDN on any desktop for Windows users:

  1. Go to the Start Menu button and type “device name”. Click the View Your PC Name menu.
  2. Select Advanced system settings, and you should see the Full Computer Name section – that’s the FQDN.
The full computer name in Windows' system properties

Alternatively, use a simple command by right-clicking on the Start Menu and selecting Windows Terminal. Then, enter the ipconfig /all command to reveal a complete Windows IP configuration, including the hostname, primary DNS suffix, and connection-specific DNS Suffix.

The FQDN information in Windows Terminal after entering the ipconfig :all command

For macOS users, click the System Preferences icon in the Dock or navigate to the Apple menu at the left top, select System Preferences, and choose Sharing.

At the top, you should see an FQDN and a connection-specific DNS suffix under the Computer Name section.

The FQDN detail in the macOS' System Preferences

Meanwhile, Linux users can find FQDN by entering the hostname –fqdn command line in the Terminal. To open the Terminal, press CTRL + ALT + T or search for it by clicking the Dash icon, typing “terminal” in the search box, and selecting the Terminal application.

A command line in Terminal to find FQDN in Linux

Conclusion

A fully qualified domain name (FQDN) enables a specific computer or a server on the internet to be uniquely identified within the domain name system (DNS).

This full domain name contains:

  • Hostname
  • Subdomain (if any)
  • Second-level domain
  • Top-level domain (TLD)
  • Trailing period

Unlike fully qualified domain names, including complete levels of a domain, partially qualified domain names (PQDNs) consist of only the hostname or domain name – a second-level domain and a TLD. Since it is shorter, a PQDN helps people remember the address much more quickly.

FQDNs are essential when you want to obtain an SSL certificate, migrate to a different server, or connect to a remote host or a virtual machine.Where to find an FQDN will depend on your operating system. For example, Windows and Linux-based users can check it using the Terminal, while Apple stores FQDNs on the System Preferences panel.

We hope this article helps you understand FQDN. If you’re planning to buy a domain name, make sure to purchase it from a reliable registrar such as Hostinger. Let us know if you have any questions by leaving comments below.

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Maulidina Marlita

Lidin is a Writer for Hostinger’s Content team. With a passion for digital marketing and writing, she is excited to share her knowledge with people around the globe. When she’s not writing, you can find her editing videos.