As you read email or search the internet, have you ever found yourself wondering, ‘How does the Internet work?’, or, ‘What exactly is the Internet?’ For those of you who would like to have an understanding of what makes web pages show up on your computer screen or how that email gets to you so fast from your cousin in Chicago, this week’s article is for you. The Internet is really just a world-wide network of computers. To be more precise, it is a network of networks. For example, when you dial up to your ISP (Internet Service Provider, such as People PC, East KY Connect, etc), your computer becomes part of the ISP’s computer network. Now, the network owned by the ISP is also part of a larger network. And on it goes, with more and more networks connecting to other networks. Some computers on this network of networks, or inter-network, or Internet, are connected to other computers by simple phone lines (like your PC). Other computers are connected by ultra high-speed lines (such as fiber, T-1, T-3, OC-45, etc). When you want to view a web page, say www.Yahoo.com, your computer sends that request up to the ISP’s network, which tries to figure out what other computer on the Internet is known as ‘Yahoo.com’. It then forwards the request to any number of other servers (a server is a high-end computer) with a message something akin to, ‘This user wants to view Yahoo.com, please forward this request to Yahoo.com and send me back the results’. Each server that receives this message will forward it on until it finally reaches a server called ‘Yahoo.com’. The computer at Yahoo.com then gets the information needed to display the webpage and returns it. The return path may go through a number of servers on the Internet until it finally reaches your ISP’s network. The ISP then sends the webpage to your PC. As soon as you click a link on the webpage to go to another page within the site, guess what, the same thing happens all over again. Now, for this to happen as efficiently and as quickly as it does, there has to be a little magic added into this monstrous world-wide network. That is where things like routing and DNS come in to play. You see, every computer on the Internet (including your PC when you are connected) is given a unique number, called an IP address. This IP address is the exclusive property of that computer while it is online. So, your computer has a unique IP address as does all the computers that process the request all the way to Yahoo.com, which also has an IP address. When you request a web page, one of the first things to happen is that the name Yahoo.com is translated into the number representing Yahoo.com’s IP address. This is a function of DNS, or Domain Name System. Computer’s don’t know what ‘Yahoo.com’ means, but they do know what ‘216.109.112.135’ (Yahoo’s IP) means. Once the destination’s IP address is known, routing comes into play. Routing means simply what its name implies it is a method of finding a route to a destination. For example, if I am at my home in Jackson, Kentucky and want to view Yahoo.com, which may be hosted on a server in Sunnyvale, California, it just wouldn’t work very well if my request went to a server in England only to be ultimately transferred all the way back to the US. A router on the Internet tries to find the most efficient path of servers along the network to get to Yahoo. Each server that receives the request will, in turn, do its own routing to find the best possible path in which to forward the request. Once Yahoo’s server processes the request the same thing happens in reverse. So, with routing, my request for Yahoo will start in Jackson at my PC, and then may be forwarded to a server in St. Louis, then on to California. When the page is returned to me, it may take a completely different path. If the St. Louis server is busy at the time, my request may be returned by way of Atlanta or Lexington. This is a really high-level overview of what makes the Internet tick. There are tons of other technologies in play that all work together to make the Internet the revolutionary thing that it is. Once it all comes together, it is truly a wondrous thing. [ Now, for the Cool Site of the Week... Since we’ve been talking about what makes the Internet work, you may be curious about how other things work as well. If so, visit HowStuffWorks.com. This is simply one of my favorite sites on the web, with easy to read articles and pictures showing you the inner workings of pretty much anything you are curious about. Here, you can read about anything from how anti-lock brakes work to what make the human heart pump. As always, if you have any questions or suggestions for future articles, please email me at mike@MikeBryant.com.

Mike Bryant has worked as a professional software developer for over ten years. A born entrepreneur, he currently owns Centrant, LLC, a software consulting firm specializing in custom software for small businesses. He currently resides in Jackson, Kentucky with his wife, two kids, and five computers. For more information, please visit MikeBryant.com.