Domain Geography

So now, hopefully, you have a slightly better idea of what the Internet is, where you are located on the Internet, and how you are connected.

The next question is, how are those connections made? How do computers make connections?

One way of answering that is to point out that each computer has an address. We learned about these back in the Unit on the Operating System: each computer uses an IP address.

By now, you should be familiar with the idea that your computer is part of a LAN, or Local Area Network--a private group of computers in a single building, like units in an apartment complex. Like apartments, each computer has an internal address, which is from the following IP address blocks:

  • 192.168.x.x
  • 172.16.x.x ~ 172.31.x.x
  • 10.x.x.x

These addresses are used only within LANs, in small, private networks, however. These small networks usually connect to the outside using a network serverA "network server" is a server computer which makes connections between computers. For example, the building's network server manages traffic between all computers in the LAN, and between computers in the LAN and the Internet., which usually has an external address, which can be almost any IP address except the few listed above as reserved for internal networks.

If you recall from the previous chapter, an IP address is a four-number code assigned to a server. Each of the four numbers is "8-bit," or between 0 and 255. Here's an example:

Because the above address has 4 groups of 8 binary digits, we call it a 32-bit address. That many digits allows for over 4 billion separate addresses. However, these addresses have been given out inefficiently. Some institutions with only hundreds of computers have been given tens of thousands of addresses. Most IP addresses are wasted, and never used. As a result, we are actually running out of addresses!

To fix this problem, a new IP address system, called "IPv6" (Internet Protocol version 6) has been created. Using 128 bits, it has space for 340,000,000,000,000,000,000,000,000,000,000,000,000 addresses, or 340 undecillion (yes, that's a real word). So, we should have enough of these addresses for a while. With the new IPv6 addresses, you will not see the old 0-255 number system, though; IPv6 addresses are shown in base-16, or "hexadecimal," and look like this:



Now we come to domains. What is a domain? Put simply, a domain is an address on the Internet which is maintained by various servers (e.g., email servers, web servers, etc.). We usually think of a domain as containing a "web site," but domains can contain much more than just that.

Each domain can have an IP Address. To connect to the domain, we type in its address, and our computer seeks that somain and makes contact.

There is a problem, however. These IP addresses are much too difficult to remember. Seriously, could you imagine someone saying, "Check out my web site at 2001:0db8:85a3:08d3:1319:8a2e:0370:7334!" Me neither.

As a result, we needed a better way to express an address on the Internet. What was created is called the Domain Name. You know these--it's That's a domain name, like,, or

Each domain name is connected to an IP address. In a way, they are the same thing; you can type an IP address directly into a browser. Go ahead, try this address: That will take you to LCJ's home page. Another way to get to the exact same page is to go to So: =

Think of it in the same way as you think about a phone number. If you want to call somebody, you punch in their telephone number. However, if your cell phone is smart enough, you would simply look up their name, and the phone would automatically find the right number and connect you.

That's what browsers do: when you type in a domain name, they look up the IP address for that domain name and they take you to it.

The last few letters, like .com, .net, or .org are called top-level domains. What we usually call a "domain name" is actually a subdomainA "subdomain" is one part of a domain; there may be many subdomains within a domain, like rooms in a house. of .com or .net or whatever.

Most people are used to typing the letters "www" before a domain name, as in "". That "www" is also a subdomain--it refers to the part of the domain "" which is reserved for the web site. There may bo other subdomains for email and other network connections, using various protocols:
web site
file transfer point
incoming email
outgoing email

Top-level Domains

Top-level domains come in various types, but the main ones are .com, .net, and .org for private web sites, and .gov, .edu, and .mil for government, educational, and military web sites. These are just a few, however; there are many more:

network entity
name (personal)
mobile (cell phone-specific)
U.S. government only
U.S. military only
accredited educational only
air-transport industry only
travel-related entities only

There are more, and new ones are created from time to time. Top-level domains proposed but not yet official: .eco (environmental organizations), .mail (for email, as a way of cutting off spam), .geo (for geographical locations), and others.

National Domains

Each country has a domain, which it controls. Some examples:

Sri Lanka
United Kingdom
United States

These are usually used with 2-letter versions of the common suffixes, such as "", "", and "".

Each country controls the use of its suffix, and can charge whatever amount of money that it likes. The ".jp" suffix is sometimes pretty expensive.

One country became rich because of this naming system. The tiny country of Tuvalu did not get ".tu" because Tunisia is before it, alphabetically. So Tuvalu got ".tv". However, there are rumors that when Tuvalu eventually disappears because of global warming, the ".tv" domain suffix will also disappear.

Recently, the fact that countries control domains has hit the news. There are services which create mini-URLs, to replace longer URLs which will not fit in Twitter or other short message spaces. The most famous is called, and an example address is one I have created for this web page: Click on that, and it will expand to "" and take you to this web page.

The problem? Well, these shortening services decided to end with the "ly" domain, as a cute, short, and easy-to-remember suffix. But the "ly" domain is owned by Libya, not recognized as a liberal, free-wheeling place. Libya has "morality laws," and a web site with the domain "" was seized and taken down by the Libyan government for "promoting illegal activities"--namely, shortening URLs to pornography sites.

So, we have defined a domain as being a location on the Internet equal to an IP address, allowing you to make contact with a collection of servers which host a web site. Although I have noted that "top level" domains are just the ".com" and ".org" suffixes, from here on I will refer to privately-held domains, like "" and "" as "domains."