HTML (English) 07

Where in the World?

Now that you have told the web server how you want your document delivered, you need to tell it what document you want to get. That task breaks down into two parts. Unless you live alone, your home address does not uniquely identify you. Rather, it identifies the place where you reside. URLs are similar. The address part of a URL is not the address of a particular document, but is the address of a particular machine, or host, that contains the document.

Technically, every machine connected to the internet has a unique address. Unfortunately, this address- called the internet protocol (IP) number- is not especially user- friendly. The IP number for a particular machine is a set of four 8-bit numbers separated by periods. That means you could have an IP address of 111.222.111.222., but not an address of 111.222.333.444, because the highest value an 8-bit number can hold is 255. In addition to the IP number for a specific machine, you can also include an optional TCP/IP (Transfer control / Internet protocol) port number after the address.

Fortunately for those who don’t memorize lists of 12- digit numbers for sport, there is an easier way. Instead of using an IP number, which is sort of like using latitude and  longitude to locate your house , you  can simply use what is called the host name. For  the waiter group, the host name for the web site is  www.mcp.Hmmm. That looks much easier, doesn’t it!

Notice that the name www.mcp.com, has two parts. This structure is similar to your home address. You not only have a street name and number, but you also have a city, state, and country part to your address. In the internet world, address are broken up into two parts: the host name and the domain name.(One potential point of confusion is that this complete address is also sometimes just called a host name. Don’t worry. This works just like your own address: You can refer to either the abbreviated form, 123 main streets, or the fully qualified form with address, city, state, and ZIP code. 123 main streets or the fully qualified form with address, city, state, and ZIP code. Both are your address, but one is more detailed than the other.)

The domain name is the name assigned to an entire network. Just like the city, state, and country divisions that for mail delivery, the internet has been broken up into several broad domains that specify what type of organization or country a machine belongs to. Thus, commercial organizations belong to the .com domain, universities to the .edu domain , and government organizations  to the .gov domain . In addition to specifying the ‘cyber country’   of a particular host, domains may also be divided into cities or counties. There are local network divisions   within an institution or organization. For example, all the hosts on the Waite group’s network are in the mcp. COM domain.

Nonetheless, the  document you are looking for has to reside on a particular machine at a particular address, just as you live at a particular street  address  in a  particular  city, state, and country. This particular machine address is called the host name. The host name of the Waite group’s web server is www, which is more fully known as www.mps.com.