Domain Names Explained

What is a domain name? Domain names are a building block of how we address resources on the Internet. Domain names are a tool for simplifying the location of these resources, so that people can easily remember and understand them.

The easiest way to illustrate a domain name is to use an example, so our example will be this web site, Of Zen and Computing. Look up in the address bar at the top of your web browser — our domain name, www.ofzenandcomputing.com, is present in the address you see there. The domain www.ofzenandcomputing.com identifies the location where this web site and all it’s pages are hosted.

The Technical Details of Domain Names

Network resources are actually identified by sets of numbers called IP addresses. Computer scientists and network architects realized that remembering many different numerical addresses would not be practical for the average computer user, and so we have domain names. Domain names are synonyms for these numerical addresses. When you request the domain name www.ofzenandcomputing.com, that domain gets translated into the actual numerical IP address, and your request is then sent to that IP.

The Parts of a Domain Name

Domain names have different parts, separated by periods:

• Top-Level Domain Name The top-level domain of www.ofzenandcomputing.com is .com. We share this name space with every other web site under the .com umbrella. There are many different top-level domains, such as .com, .net, .org, .name, and .tv.
• Second-Level Domain Name The second-level domain name follows directly to the left of the top-level domain, identifying us out of the many other sites residing under that “dot com umbrella”. Our second level domain is ofzenandcomputing. The top-level and second-level domain names combine to form the domain name that we have registered, ofzenandcomputing.com. We are in control of all addresses under the ofzenandcomputing.com umbrella, which leads me to the next part…
• Subdomains Subdomains follow directly to the left of the second-level domain name. The subdomain you’re accessing right now, to view this page, is the www subdomain of ofzenandcomputing.com. Our Tech Shop lives under a different subdomain: shop.ofzenandcomputing.com. There’s no www to be found in the Tech Shop’s address.

  There can be many levels of subdomains. If we were so inclined, we could place content at please.visit.us.at.ofzenandcomputing.com.

A Domain Name is not a URL

A domain name is part of an address, but often not the entire address, especially on the Web. The entire address of a web page is called a URL, which is short for Uniform Resource Locator. The URL to our “About” page is http://www.ofzenandcomputing.com/about. Our domain name is one ingredient in the larger URL. Another example would be your email address. Your full e-mail address would be you@example.com, in which the domain name example.com is one ingredient.

Domain Names Aren’t Limited to the Web

Domain names aren’t just used to identify web sites. Domains are used to address many other network resources. For example:

• Domain names are used in e-mail addresses, e.g. you@example.com.
• Domain names can identify Internet Relay Chat servers, e.g. irc://irc.example.com.
• Domain names lead to ftp servers, e.g. ftp://ftp.example.com.

Where to Get Domain Names

Domain names can be purchased through domain name registrars, which are companies who are authorized to register domains with the Internet’s root domain servers. Of Zen and Computing’s registrar is DreamHost.