“What’s your name?” is the first question most people ask of one another. Shakespeare said, “If a rose by any other name would smell as sweet…” It’s usually the first piece of information we have about a company or person.
It’s important that that first impression is short, memorable and easy to find again. For a computer without human attributes, this can’t be more important. Your Fully Qualified Domain Name (FQDN or FQDM) is how other computers (and the people behind them) find you.
In some very well-publicized internet fraud cases, Fully Qualified Domain Names were faked, copied or bootlegged. But what is an FQDN and how does it apply to your website? Read on to learn more.
A Fully Qualified Domain Name (FQDN or FQDM) is also known as an absolute domain name. It is the human-readable equivalent of an IP (Internet Protocol) address. It specifies the full path of the host within the domain name service.
An FQDN (FQDM is a frequent-enough typo) is written with the hostname, domain name, and top-level domain name. It specifies the exact location of the host within the hierarchy. For shared host servers, this exact location lookup is important.
A Fully Qualified Domain Name always has a consistent format. It is written: [host name].[domain].[top-level domain]. FQDN is read from right, the root, to left, the host.
The hostname specifies a particular service or protocol for a domain such as “www” or “ftp” in “www.service.com” or ftp.irish.net, respectively.
For example, the incoming mail server on the google.com domain could use the FQDN mailserver.google.com.
Here are some more examples of Fully Qualified Domain Names:
Ambiguous or partially qualified domain names are those that do not give the full path. For example, mailserver is not an FQDN because any number of domains might have a server by the name “mailserver”.
Mailserver.yahoo.com and mailserver.micro.com.ie are two examples of domains having similar hostnames. Remembering only the hostname doesn’t drive much traffic to you. Similarly, yahoo.com isn’t a fully qualified domain name because the hostname isn’t given.
Most browsers (like Chrome or Safari) will automatically assume the hostname is www. but that is not always the case. An FQDN also requires the terminating period after the top-level domain, such as en.wikihistory.org. This ending period is not required by most browsers.
Domain names that do not contain the full path are called Partially Qualified Domain Names. “Mailserver” is one such example. You know the hostname, but not which domain.
Google.com is another. If you send mail to google.com, you have not specified a hostname.
A Partially Qualified Domain Name is used for convenience, in certain contexts. If the domain is already known elsewhere in a certain task, a common shortcut is to just refer to the host name without referring to the full path. This is the equivalent of your town and postcode. Your FQDN would be your full mailing address.
A systems administrator could refer to the Fully Qualified Domain Name like gd.learngaelic.net or just shorten it and use the hostname of gd in DNS records. If this shortcut is used, the rest of the system understands the context, that gd refers to gd.learngaelic.net.
When attempt connection to a host (such as logging into the administrator interface on your online store) you must use the FQDN. A DNS server resolves the FQDN hostname to its numeric Internet Protocol address by referring to its DNS table. The host computer is pinged and it returns a prompt.
If you try to connect to a server with only the hostname (without the domain information) the incomplete information to the DNS table results in error. You won’t contact the server you want or you may get sent somewhere completely different. This is not unlike boarding an aeroplane bound for Toledo and waking up in Toledo, Ohio, USA instead of sunny Toledo, Spain.
This happens if the DNS suffix search order properties are incorrect, or if you have a corrupted DNS table. In cases like this, FQDN entry allows DNS to locate the server. In simple terms, like telling the cab driver to drop you off at the Ryanair terminal rather than International Departures.
To connect to a remote host outside your local internet service provider (ISP), you will need to use the FQDN. Your local system administrator would keep DNS tables for things in its own domain. Most DNS servers in one domain do not have listings to resolve hosts in another domain or unrelated ISP.
Fraudsters exploit the FQDN system by faking hostnames and subdomains. They may create a something called fraudwatch.paypal.com.security-check.com. They then send copycat notices asking people to “change their password” at the fake site, effectively stealing people’s personal information.
The FQDN, in this case, is hostname “fraudwatch.paypal.com”, domain name “security-check”, top-level domain “.com”. Sneaky, isn’t it?
Now you know what an FQDN is (or FQDM if you have fat fingers). If you ever had to do the email setup on a new phone or the remote sign-in for a computer for the first time, you’ve used an FQDN.
The FQDN is the unique internet identifier of a particular computer. Browser URLs are often Partially Qualified Domain Names, with the browser filling in the trailing information, such as the initial www. or the terminating period. These unique addresses are translated into numbers that are used to deliver your data where it needs to go.
If you are ready to leap into the world of your own websites, we’re here to help. Contact us today!
