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CompTIA A+ Certification All-in-One Exam Guide

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in Chapter 19. Wireless connections are a mixed bag, depending on the

device and service you have. Some are built-in, while others use a box you

attach to your LAN. Satellite is the odd one out here; it may use either a

modem or a NIC, depending on the particular configuration you have,

although most folks will use a NIC. Let’s take a look at all these various

connection options, and then finish this section by discussing basic router

configuration and sharing an Internet connection with other computers.

Dial-Up

A dial-up connection to the Internet requires two pieces to work: hardware to

dial the ISP, such as a modem or ISDN terminal adapter; and software to

govern the connection, such as Microsoft’s Dial-up Networking (DUN). Let’s

look at the hardware first, and then we’ll explore software configuration.

Modems

At some point in the early days of computing, some bright guy or gal noticed

a colleague talking on a telephone, glanced down at a computer, and then put

two and two together: Why not use telephone lines for data communication?

The basic problem with this idea is that traditional telephone lines use analog

signals, while computers use digital signals (see Figure 21-6). Creating a dialup

network required equipment that could turn digital data into an analog

signal to send it over the telephone line, and then turn it back into digital data

when it reached the other end of the connection. A device called a modem

solved this dilemma.

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