Chapter 1: Networks Will Not Take Over the World, and Other Network Basics

Computer networks get a bad rap in the movies. In the Terminator movies, Skynet (a computer network of the future) takes over the planet, builds deadly terminator robots, and sends them back through time to kill everyone unfortunate enough to have the name Sarah Connor. In The Matrix movies, a vast and powerful computer network enslaves humans and keeps them trapped in a simulation of the real world. And in one of Matthew Broderick's first movies, War Games, a computer whiz kid nearly starts World War III by connecting to a Defense Department network and playing the game Global Thermonuclear War.

Fear not. These bad networks exist only in the dreams of science fiction writers. Real-world networks are much more calm and predictable. They don't think for themselves, they can't evolve into something you don't want them to be, and they won't hurt you-even if your name is Sarah Connor.

Now that you're over your fear of networks, you're ready to breeze through this chapter. It's a gentle, even superficial, introduction to computer networks, with a slant toward the concepts that can help you use a computer that's attached to a network. This chapter goes easy on the details; the detailed and boring stuff comes later.

What Is a Network?

A network is nothing more than two or more computers connected by a cable (or in some cases by radio connection) so that they can exchange information.

Of course, computers can exchange information in ways other than networks. Most of us have used what computer nerds call the sneakernet. That's where you copy a file to a diskette, a CD-RW disc, or a removable flash drive, and then walk the data over to someone else's computer. (The term sneakernet is typical of computer nerds' feeble attempts at humor, and why not? As a way to transfer information, sneakernet is feeble.)

The whole problem with the sneakernet is that it's slow-plus, it wears a trail in your carpet. One day, some penny-pinching computer geeks discovered that connecting computers with cables was cheaper than replacing the carpet every six months. Thus, the modern computer network was born.

You can create a computer network by hooking together all the computers in your office with cables and using the computer's network interface (an electronic circuit that resides inside your computer and has a special jack on the computer's backside). Then you set up your computer's operating system software to make the network work, and-voilà-you have a working network. That's all there is to it.

If you don't want to mess with cables, you can create a wireless network instead. In a wireless network, each computer is equipped with a special wireless network adapter that has little rabbit-ear antennas. Thus, the computers can communicate with each other without the need for cables.

Figure 1-1 shows a typical network with four computers. You can see that all four computers are connected by a network cable to a central network device: the hub. You can also see that Ward's computer has a fancy laser printer attached to it. Because of the network, June, Wally, and the Beaver can also use this laser printer. (Also, you can see that the Beaver stuck yesterday's bubble gum to the back of his computer. Although the bubble gum isn't recommended, it shouldn't adversely affect the network.)

Figure 1-1: A typical network.

Computer networking has its own, strange vocabulary. Fortunately, you don't have to know every esoteric networking term. Here are a few basic buzzwords to get you by:

• LAN: Networks are often called LANs. The acronym LAN stands for local- area network. It's the first TLA, or three-letter acronym, that you see in this book. You don't really need to remember it, or any of the many TLAs that follow. In fact, the only three-letter acronym you need to remember is TLA.

• FLA: You may guess that a four-letter acronym is an FLA. Wrong! A four-letter acronym is an ETLA, which stands for extended three-letter acronym. (After all, it just wouldn't be right if the acronym for four-letter acronym had only three letters.)

• On the network: Every computer connected to the network is said to be on the network. The technical term (which you can forget) for a computer that's on the network is a node.

• Online: When a computer is turned on and can access the network, the computer is said to be online. When a computer can't access the network, it's offline. A computer can be offline for several reasons. The computer can be turned off, the user may have disabled the network connection, the computer may be broken, the cable that connects it to the network can be unplugged, or a wad of gum can be jammed into the disk drive.

• Up: When a computer is turned on and working properly, it's said to be up. When a computer is turned off, broken, or being serviced, it's said to be down. Turning off a computer is sometimes called taking it down. Turning it back on is sometimes called bringing it up.

Tip 

Don't confuse local-area networks with the Internet. The Internet is a huge amalgamation of computer networks strewn about the entire planet. Networking the computers in your home or office so that they can share information with one another and connecting your computer to the worldwide Internet are two separate, but related, tasks. If you want to use your local-area network to connect your computers to the Internet, you can consult Chapter 10 for instructions.