three things: files, resources, and programs.
Accessing the Internet
Probably the main reason most small business and home networks exist is to allow everyone to access the Internet through a single shared Internet connection. In Figure 1-1, you can see that the wireless router is connected to the Internet. By sharing this connection, all the computers on the network, whether wireless or via cables, can access the Internet through the wireless router.
It’s important to note that nearly all wireless routers also contain a built-in firewall. The firewall helps protect the computers on the network from the imminent dangers of the Internet. The moment you connect a home or office network to the Internet, cybercriminals will begin trying to break into your network and try to trick you into divulging sensitive information, such as the password to your bank account.
Sharing files
Networks enable you to share information with other computers on the network. Depending on how you set up your network, you can share files with your network friends in several different ways. You can send a file from your computer directly to a friend’s computer by attaching the file to an email message and then mailing it. Or you can let your friend access your computer over the network so that your friend can retrieve the file directly from your hard drive. Yet another method is to copy the file to a disk on another computer and then tell your friend where you put the file so that your friend can retrieve it later. One way or the other, the data travels to your friend’s computer over the network cable and not on a CD or DVD or flash drive, as it would in a sneakernet.
Sharing resources
You can set up certain computer resources — such as hard drives or printers — so that all computers on the network can access them. For example, the printer in Figure 1-1 is a shared resource, which means that anyone on the network can use it. Without the network, Marge, Lisa, and Bart would have to buy their own printers.
Hard drives can be shared resources, too. In fact, you must set up a hard drive as a shared resource to share files with other users. Suppose that Lisa wants to share a file with the Bart, and a shared folder has been set up on Homer’s computer. All Lisa has to do is copy his file to the shared folder in Homer’s computer and tell the Bart where she put it. Then, when the Bart gets around to it, he can copy the file from Homer’s computer to his own.
Sharing programs
Instead of keeping separate copies of programs on each person’s computer, put programs on a drive that everyone shares. For example, if ten computer users all use a particular program, you can purchase and install ten copies of the program, one for each computer. Or you can purchase a ten-user license for the program and then install just one copy of the program on a shared drive. Each of the ten users can then access the program from the shared hard drive.
Another common method for software vendors to license their software is through a monthly or yearly subscription. You just give them your credit card number, and they give you the right to use the software. You need a working Internet connection so that the software can confirm that you have a valid subscription each time you run the software.
Another benefit of networking is that networks enable computer users to communicate with one another over the network. The most obvious way networks allow computer users to communicate is by passing messages back and forth, using email or instant-messaging programs. Networks also offer other ways to communicate: For example, you can hold online meetings over the network. Network users who have inexpensive video cameras (webcams) attached to their computers can have videoconferences. You can even play a friendly game of Hearts over a network — during your lunch break, of course.
Servers and Clients
The network computer that contains the hard drives, printers, and other resources that are shared with other network computers is a server. This term comes up repeatedly, so you have to remember it. Write it on the back of your left hand.
Any computer that’s not a server is a client. You have to remember this term, too. Write it on the back of your right hand.
Only two kinds of computers are on a network: servers and clients. Look at your left hand and then look at your right hand. Don’t wash your hands until you memorize these terms.
The distinction between servers and clients in a network has parallels in sociology — in effect, a sort of class distinction between the “haves” and “have-nots” of computer resources:
Usually, the most powerful and expensive computers in a network are the servers. There’s a good technical reason: All users on the network share the server’s resources.
The cheaper and less-powerful computers in a network are the clients. Clients are the computers used by individual users for everyday work. Because clients’ resources don’t have to be shared, they don’t have to be as fancy. (The exception to this rule is if the users do work that requires powerful desktop computers — for example, engineering design or video processing.)
Most networks have more clients than servers. For example, a network with ten clients can probably get by with one server, but larger networks will likely require more servers.
In most networks, a clean line of demarcation exists between servers and clients. In other words, a computer functions as either a server or a client, not both. For the sake of an efficient network, a server can’t become a client, nor can a client become a server.
Other (usually smaller) networks can be more evenhanded by allowing any computer in the network to be a server and allowing any computer to be both a server and a client at the same time.
Dedicated Servers and Peers
In most networks, a server computer is a server computer and nothing else. It’s dedicated to the sole task of providing shared resources, such as hard drives and printers, to be accessed by the network client computers. This type of server is
