FQDN looks like another abbreviation that seems complicated to pronounce. It stands for Fully Qualified Domain Name, and let’s clarify what does it means. 

What is FQDN (Fully Qualified Domain Name)?

The term “fully qualified domain name”, FQDN for short, sometimes also associated with an absolute domain name, is a domain name that defines its exact location in the tree hierarchy of the Domain Name System. It specifies every domain level, including the top-level domain and the root zone. It is the most comprehensive way to write a particular domain name for a host or a computer.

Structure

Let’s take a look at the structure of an FQDN from right to left. 

  1. On the highest hierarchical level is the root label, also called the “root” of the DNS system. It is only expressed by a period or dot. When you are typing in the browser’s search, it’s unnecessary to enter this dot anymore. The browser will add it.
  2. The next highest hierarchy level is the Top Level Domain. For instance, “.com,” “.org,” or “.net.” 
  3. The Domain is on the next hierarchy level. It is the name that an owner has chosen, like Google.
  4. The hostname (Subdomain) is on the lowest label. It shows various subcategories or services, like mail or store, for example.

What is PQDN (Partially Qualified Domain Name)?

A Partially Qualified Domain Name is a Fully Qualified Domain Name, but with a missing part. It doesn’t have each of the components that will reveal the accurate location on the DNS hierarchy. To make it more clear, for example, google.com is PQDN because it is missing the web host (www.) before the domain name. 

People normally use PQDN because it is more easy and simple. Also, not to forget, it is shorter, which makes PQDN more commonly used.

Why use an FQDN?

  • Obtaining an SSL Certificate – Almost every site has one, and you need to provide the FQDN to receive it.
  • Connecting to a host remotely – When you’re connecting to a remote host that isn’t local to your ISP. The Fully Qualified Domain Name will be a requirement.
  • Access a Particular Domain Service or Protocol – If you want to set up email for specific applications, you will need it.

FQDN lookup

If you want to see the FQDN of your device, it is not a problem. Just follow the steps shown below.

On macOS:

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

On Linux: 

  1. Open the terminal application. 
  2. Write down the following command: “hostname -f” and press the Enter.
  3. You will see the FQDN. 

On Windows 10:

  1. Click the start menu, write “Control Panel,” and click it. 
  2. Inside the Control Panel, find the System and open it. 
  3. Inside the System, see the “Device specifications” and look for the “Device name.” 
  4. Then there is the FQDN. 

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