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Chapter 1
Welcome to Networking
IN THIS CHAPTER
Computer networks get a bad rap in the movies. In the 1980s, the Terminator movies featured Skynet, a computer network that becomes self-aware (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 the 2015 blockbuster Spectre, James Bond goes rogue (again) to prevent the Evil Genius Ernst Blofeld from taking over the world (again) by linking the computer systems of all the world’s intelligence agencies together to form a single all-powerful evil network that spies on everybody.
Fear not. These bad networks exist only in the dreams of science-fiction writers. Real-world networks are much more calm and predictable. Although sophisticated networks do seem to know a lot about you, they don’t think for themselves and they don’t evolve into self-awareness. And although they can gather a sometimes disturbing amount of information about you, they aren’t trying to kill 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 to Homer the concepts that can help you use a computer that’s attached to a network. This chapter goes easy on the details; the detailed stuff comes later.
Defining a Network
A network is nothing more than two or more computers connected by a cable or by a wireless radio connection so that they can exchange information.
You can create a simple computer network by using a device called a switch to connect all the computers in your network to each other. You do that by stringing a network cable from the switch to each computer. The cable plugs into a special jack on the back of each computer; this jack is connected to a network interface, which is an electronic circuit that resides inside your computer to facilitate networking. Voilà! You have a working network.
If you don’t want to mess with cables, you can create a wireless network instead. In a wireless network, the computers use wireless network adapters that communicate via radio signals. All modern laptop computers have built-in wireless network adapters, as do most desktop computers. (If yours doesn’t, you can purchase a separate wireless network adapter that plugs into one of the computer’s USB ports.) You’ll need a device called a wireless access point (WAP) to enable the computers to properly connect. In small office or home networks, the WAP is bundled with a device called a router, which lets you connect your network to the Internet. The combination of a WAP and a router is called a wireless router.
Figure 1-1 shows a typical network with five computers. This network is a home network used by a family that bears only a totally coincidental similarity to a famous TV family you may or may not have heard of. You can see that each family member has a computer that connects to the network — two of them wirelessly, three of them through cables. There’s also a printer that connects wirelessly.
In this example, the wireless router also has a built-in switch that provides several jacks for connecting computers via cable. Most wireless routers include this feature, typically with three to five wired network ports.
Although the network is a small one, it has much in common with larger networks that contain dozens, hundreds, or even thousands of connected computers.
FIGURE 1-1: A typical network.
Here’s the rundown for each of the devices connected to this network:
Lisa has a laptop computer that connects wirelessly. She uses it mostly for school.
Bart has a fancy gaming computer that’s cabled directly to the router.
Marge doesn’t have a full-fledged computer, but she does use an iPad, which is connected wirelessly.
Homer has an old computer he bought at a garage sale in 1989. He doesn’t know how to use it, but he doesn’t know that so no one tells him. Lisa set it up for him and repairs it when Homer breaks it (which happens every few months); she gets repair parts from eBay.
The printer connects wirelessly to the network and is set up so that any member of the family can print on it.
The wireless router connects to the Internet using the family’s cable TV provider. This allows everyone in the family to access the Internet.
Delving into Network Lingo
Computer networking has its own strange vocabulary. Although you don’t have to know every esoteric networking term, it helps to be acquainted with a few of the basic buzzwords:
LAN: Networks are often called LANs, short for local area network. LAN is the first three-letter acronym (TLA) of this book. You don’t really need to remember it or any of the many TLAs that follow. You may guess that the acronym for four-letter acronym is 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, offline: When a computer is turned on and can