What is a Fully Qualified Domain Name (FQDN)?

A Fully Qualified Domain Name (FQDN) is the complete address of a website or server that identifies a specific location on the internet.

An FQDN includes every part of a domain name, from the hostname or service down to the root domain. It’s called fully qualified because it provides all the information needed to locate a resource.

Here’s what typical FQDNs look like:

• mail.example.com: an example email service.
• www.support.example.com: an example support subdomain.
• blog.example.com: an example blog.
• ftp.example.org: an example FTP server.

Each part, separated by a dot, represents a different level in the domain hierarchy, working from the most specific on the left to the most general on the right.

FQDNs matter because they’re how computers find and connect to websites and services. When you type a web address into your browser, you’re using an FQDN to tell your computer which server to contact. They’re also essential for email delivery and server management.

What are the components of an FQDN?

A fully qualified domain name, also known as an absolute domain name, specifies all domain levels, including the top-level domain (TLD), in hostname.domain.tld format.

For example, the FQDN for a mail server at Yahoo might be mail.yahoo.com. Other examples include www.wordpress.org and news.bbc.co.uk.

Check out our article explaining what a domain name is to understand the differences between a simple domain name and an FQDN in more detail.

Let’s explore each element on an FQDN hierarchy:

• Hostname ‒ a label assigned to a device or service on a network. It’s part of the domain name that makes an IP address easy to remember. For example, “www” is the hostname in saleonlineat.top, indicating a web server.
• Subdomain ‒ located to the left of the main domain, it can show a specific subdivision or a service associated with a larger domain. For example, support.hostinger.com features “support” as the subdomain of hostinger.com. Note that not all domains have this element.
• Domain name ‒ consists of a second-level and a top-level domain (TLD). With hostinger.com, “hostinger” represents the second-level domain, while “.com” is the TLD.

Fully qualified domain names need a final dot or a trailing period at the end, completing the domain’s absolute path. For example, the absolute form of an FQDN would be written as “saleonlineat.top.”.

However, web browsers today usually assume the final dot, so users don’t have to include it when entering a web address.

Keep in mind that the maximum length for any single label ‒ hostname or segment of an FQDN ‒ is 63 bytes. The total length of an FQDN cannot exceed 255 bytes.

What is the FQDN used for?

An FQDN serves as the backbone for how computers communicate across the Internet. Here are the main ways they’re used:

Website access

When you type a URL into your browser, you’re using an FQDN to reach a specific website. Your browser takes that FQDN and asks the Domain Name System (DNS) to translate it into an IP address.

Without the FQDN, you’d have to memorize strings of numbers like 142.250.191.14 instead of simply typing example.com.

Email delivery

Email systems use FQDNs to route messages correctly. When you send an email to someone@company.com, mail servers use the FQDN to find the right mail server.

They also use specific FQDN like mail.company.com or smtp.company.com to identify email services within that domain.

Server management

IT administrators use FQDNs to manage different servers within their networks. Instead of tracking IP addresses, they can use descriptive names like database.company.com or backup.company.com. This makes it much easier to organize complex systems.

SSL certificates

Security certificates are tied to a specific FQDN. When a website has an SSL certificate for www.example.com, that certificate only works for that exact FQDN.

When do you need an FQDN?

FQDNs are used in various internet interactions since they are easier to remember than IP addresses. Here are several scenarios where using an FQDN is beneficial:

• Getting an SSL certificate ‒ a Secure Sockets Layer (SSL) certificate, which secures the connection between a web server and a browser, uses an FQDN to verify the server’s identity. Without an FQDN, the SSL protocol cannot operate properly.
• Connecting to a remote host ‒ when connecting to a remote host or virtual machine, using an FQDN helps DNS locate the server accurately. Relying solely on a hostname could lead to resolution failures if the local DNS can’t expand it to a complete domain name.
• Accessing specific domain services ‒ FQDNs are crucial for network communications, such as File Transfer Protocol (FTP) or email services. They ensure DNS directs traffic to the correct server.
• Migrating to a new server ‒ when migrating your services to another server, an FQDN lets you update only the DNS records for the new IP address. This way, you can minimize downtime due to IP address changes.

How to find an FQDN

Here’s how you can find your own FQDN, depending on the operating system that you use.

Windows

For users on the Windows operating system, follow the steps below to locate the FQDN in advanced system settings:

1. Open the Start menu and open View your PC name.
2. In the System tab, select Advanced system settings.

3. Locate your FQDN in the Full computer name field.

Another way to locate an FQDN on Windows is by using the command prompt. Here’s how:

1. Open Terminal in the Start menu.
2. Enter the ipconfig /all command to reveal the Windows IP configuration, including the hostname, primary DNS suffix, and connection-specific DNS Suffix.

macOS

For macOS users, follow these steps to locate the FQDN:

1. Click the System Settings icon in the Dock. Alternatively, navigate to the Apple menu at the top left and select System Settings → Sharing.
2. Scroll down to the Local hostname section. That would be your FQDN and connection-specific DNS suffix.

Linux

Meanwhile, Linux users can find FQDN through the Terminal. Press CTRL + ALT + T to open the Terminal application and enter the hostname –fqdn command line. You can also use this command in PuTTY, a popular terminal emulator. See our guide on using PuTTY to access your server.;

What is the difference between FQDN and other types of domain names?

While FQDNs give you the complete address, other types provide partial information or serve different purposes. Here’s how they compare:

FQDN vs Partially Qualified Domain Name

A Partially Qualified Domain Name (PQDN) is an incomplete web address that doesn’t include the full path specified by an FQDN. It might just be the hostname or part of the domain structure, often missing pieces like the subdomain or even the top-level domain.

For example, typing hostinger.com or saleonlineat.top will both redirect you to the same place – https://hostinger.com.

Website developers often set up their DNS to handle these redirects automatically. PQDNs work because they’re shorter and easier for users to type and remember.

FQDN vs absolute domain name

An absolute domain name is technically the same as an FQDN, but with one slight difference – it ends with a dot. The dot represents the root of the DNS hierarchy.

So saleonlineat.top. (with the dot) is the absolute form, while saleonlineat.top (without the dot) is the FQDN most people recognize. In practice, browsers and most applications handle them in the same way.

FQDN vs Uniform Resource Locator (URL)

A URL is the complete web address, including the FQDN, the protocol, and often additional path information. For example, https://blog.hostinger.com/web-hosting-guide is a full URL where blog.hostinger.com is the FQDN portion.

The URL tells you how to access the resource (https), where to find it (the FQDN), and what specific page or file to request.

Next steps: Implementing FQDN

Most hosting providers, including Hostinger, automatically set up basic FQDNs when you add a domain to your account. Your primary domain (yoursite.com) and the www version (www.yoursite.com) will typically work right out of the box.

For email services, Hostinger makes FQDN setup incredibly simple. When you set up Hostinger Email through hPanel, all the necessary DNS records, including MX, SPF, and DKIM records, are set up without you needing to configure anything manually.

But if you want to add subdomains for different services, you’ll need to set those up yourself through hPanel. For different parts of your website, you can create FQDNs like blog.yoursite.com, shop.yoursite.com, or api.yoursite.com.

For more advanced DNS management, you can use hPanel’s DNS zone editor. Here you can add custom A records, CNAME records, and other DNS entries if you need specific FQDNs for third-party integrations.

Ready to get started? Log in to hPanel and add any additional subdomains or custom FQDNs you need for your specific setup.

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