Introduction to domain names and DNS

This article introduces basic domain-related concepts such as top-level domains, subdomains, and DNS.

Domain names

Even if you have never hosted a web site before, you have undoubtedly used domain names. Every time you use a web browser to visit a web site by name, such as a2hosting.com, you are using domain names.

Domain names are organized hierarchically from right to left. The right-most portion of a domain name is called the top-level domain (TLD). The .com TLD is probably the most well known, but there are many others, such as .net, .org, .edu, and .mil. (Country codes, such as .us and .fr, are also TLDs.) When you register a domain name, you can choose which TLD to use (though some TLD's, such as .edu and .gov, are restricted to certain types of organizations).

The next domain name level after the TLD is called the second-level domain. This is the part of the domain name that you define. For example, a2hosting is the second-level domain in a2hosting.com. When you purchase a domain name, this is the portion that you “own”, as well as any subdomains beneath it. A domain name always contains a TLD and a second-level domain.

As you may have guessed, a subdomain is a third-level domain. The www subdomain is probably the most well known, but you can name subdomains anything you want. Subdomains are sometimes used to subdivide web site functionality. For example, you could have an English version of your web site at en.example.com, and a French version at fr.example.com.

DNS and name servers

Without the Domain Name System (DNS), the Internet would be a much less user-friendly place. Instead of using easily remembered names such as a2hosting.com, we would have to use a sequence of numbers like 75.98.175.166 (also known as an IP address) every time we wanted to visit a web site or access a service on the Internet. DNS translates human-readable domain names into numeric IP addresses that computers can understand.

When you purchase a domain name from a third-party registrar, you own the name, but it initially does not point to anything. (Technically, a domain registrar often “parks” the domain, and visitors to the domain see a generic web page provided by the registrar.) To enable users to access your web site using the domain name, you must define the name servers that the domain should use.

Name servers are computers that use DNS to translate the human-reabable domain names into IP addresses. Name servers often contain ns in their domain names (for example, ns3.a2hosting.com). If you purchase a domain name directly from A2 Hosting, you do not have to worry about configuring name server settings, because we take care of this for you. However, if you have purchased a domain name with another registrar (for example, eNom or Go Daddy), you must update the domain's name server settings to “point” to A2 Hosting's name servers. After you do this, users will be able to visit your web site by typing the domain name in their web browser.

Where to go from here

Now that you know the basics of domains, how do you get your domain to work with A2 Hosting's servers? There are three options for setting up your domain to work with A2 Hosting:

• If you purchase your domain directly from A2 Hosting, no further action is required. A2 Hosting takes care of the name server (DNS) settings for you.
• If you already own a domain that you purchased from a different registrar or hosting company, you can transfer the entire domain to A2 Hosting. All aspects of the domain, including billing and domain administration, are transferred from the registrar to A2 Hosting. For information about how to do this, please see this article.
• If you already own a domain that you purchased from a different registrar or hosting company, you can change the domain's name server (DNS) settings to point to A2 Hosting's servers. Unlike a transferred domain, billing and domain administration remain with the domain's current registrar. For information about how to do this, please see this article.

More Information

• For more information about DNS, please visit http://en.wikipedia.org/wiki/Domain_Name_System.
• To view a list of all top-level domains (TLDs), please visit http://www.iana.org/domains/root/db.