howtouselinux

Understanding FQDN with Examples

Table of Contents

A Fully Qualified Domain Name (FQDN) is the complete domain name of a specific computer, or host, online. A FQDN gives its precise location in the hierarchy of DNS records. It is the complete address for websites and other computers and entities accessing the Internet resolving to the root domain.

An FQDN is comprised of several elements: a hostname and a domain name. These elements are separated by a period.

Example of an FQDN

The following example clarifies the structure of a fully qualified domain name:

www.howtouselinux.com.

[Host name].[Domain].[TLD].[Root]

In a name server’s directory, the dot on the far right is always included in the FQDN.

  • The “host” or “hostname” part is www
  • The “domain” part is howtouselinux.com
  • The FQDN is www.howtouselinux.com.

Here is another example of FQDN. Some clarifications about the terminology; consider this example: foo.example.com

  • The “host” or “hostname” part is foo
  • The “domain” part is example.com
  • The FQDN is foo.example.com

Structure of FQDN

The structure of an FQDN is predefined by the domain name system (DNS). The names of the individual levels in the domain name area are called “labels” and are separated from one another by dots. Each label must consist of 1 to 63 characters and the total FQDN may not exceed 255 characters in total. Only letters, numbers, or dashes can be used. Each label has to have either a letter or a number at the beginning.

The fully qualified domain name consists of three or more labels: The top level domain, the domain names, optional subdomains, and the host name. I

Take www.howtouselinux.com, for example. The first element and domain level of the FQDN is the top level domain (TLD), which, in this case, is “.com.” Within the TLD, howtouselinux is the assigned domain name/second-level domain. Lastly, “www.” is the hostname.

How to find your domain’s FQDN

When you’re working with a domain name, it’s important to understand what a Fully Qualified Domain Name is and how to find it. Your FQDN is the complete address of your site, including the hostname and top-level domain. It’s used to identify your site on the internet and can be useful for troubleshooting purposes.

To find your FQDN, open a terminal window and run the following command:  nslookup yourdomain.com . The output will show you the full address of your website. You can also use this command to troubleshoot problems with your site or email service.

Why does my domain need a FQDN ?

Your FQDN is essential for identifying your website on the internet. It’s also necessary for email addresses, since they must include a domain name. In some cases, you may need to provide your FQDN to your web host or email provider in order to set up service.

What are the benefits of having an FQDN

There are several benefits of having a Fully Qualified Domain Name. They include:

  • – Easier troubleshooting – If you experience problems with your website or email service, your FQDN can help you identify the source of the problem.
  • – More professional appearance – A domain name with an FQDN looks more professional and trustworthy than one without.
  • – Improved SEO – Having a complete domain name can improve your site’s search engine ranking.
  • – Greater branding potential – An FQDN lets visitors know exactly where they are and reinforces your brand identity.

How to look up a FQDN?

Looking up the FQDN of our computer or server is simple. Just follow the instructions for our operating system below. If our machine does not provide the FQDN, it is not connected to a domain.

  • Windows 10. Within the taskbar’s “Search Windows” box, type “control panel” and select “system and security.” Next, select “system” and the FQDN is listed next to the Full Computer Name label.
  • Mac OS. Open terminal, and enter “hostname -f” into the prompt. Terminal will return the FQDN.
  • Linux. Open terminal and enter “hostname -A” into the prompt. The “A” is case sensitive. Terminal will return the FQDN.

Once we know our Fully Qualified Domain Name, we can make our device available online through the DNS.

More Information on FQDN

A Fully Qualified Domain Name designates the specific location of an object within the Domain Name System (DNS) hierarchy; it communicates the host’s position relative to the root of the DNS namespace.

An FQDN enables each entity connected to the internet (computer, server, etc.) to be uniquely identified and located within the internet framework.

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David Cao
David Cao

Hey there! I am David, a Cloud & DevOps Enthusiast and 18 years of experience as a Linux engineer. I work with AWS, Git & GitHub, Linux, Python, Ansible, and Bash. I am a technical blogger and a Software Engineer, enjoy sharing my learning and contributing to open-source.