To begin with, I want to provide some understanding of what these terms are so that when you read about the latest malicious code spreading through the Internet and how it gets into and infects your computer you will be able to decipher the techie terms and determine if this affects you or your computer and what steps you can or should take to prevent it. For Part 1 of this series we will cover Hosts, DNS, ISPs and Backbone.
The term host can be confusing because it has multiple meanings in the computer world. It is used to describe a computer or server that provides web pages. In this context it is said that the computer is hosting the web site. Host is also used to describe the companies that allow people to share their server hardware and Internet connection to share these as a service rather than every company or individual having to buy all their own equipment.
A host in the context of computers on the Internet is defined as any computer that has a live connection with the Internet. All computers on the Internet are peers to one another. They can all act as servers or as clients. You can run a web site on your computer just as easily as you can use your computer to view web sites from other computers. The Internet is nothing more than a global network of hosts communicating back and forth. Looked at in this way, all computers, or hosts, on the Internet are equal.
Each host has a unique address similar to the way street addressing works. It would not work to simply address a letter to Joe Smith. You have to also provide the street address- for example 1234 Main Street. However, there may be more than one 1234 Main Street in the world, so you must also provide the city- Anytown. Maybe there is a Joe Smith on 1234 Main Street in Anytown in more than one state- so you have to add that to the address as well. In this way, the postal system can work backward to get the mail to right destination. First they get it to the right state, then to the right city, then to the right delivery person for 1234 Main Street and finally to Joe Smith.
On the Internet, this is called your IP (Internet protocol) address. The IP address is made up of four blocks of three numbers between 0 and 255. Different ranges of IP addresses are owned by different companies or ISPs (Internet service providers). By deciphering the IP address it can be funneled to the right host. First it goes to the owner of that range of addresses and can then be filtered down to the specific address its intended for.
I might name my computer My Computer, but there is no way for me to know how many other people named their computer My Computer so it would not work to try to send communications to My Computer any more than addressing a letter simply to Joe Smith would get delivered properly. With millions of hosts on the Internet it is virtually impossible for users to remember the addresses of each web site or host they want to communicate with though, so a system was created to let users access sites using names that are easier to recall.