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The most common remote access connection (and, therefore, the one that the Network+ exam tests you on) is a dial-up connection over a regular analog phone line. This section covers only one type of remote access configuration; however, each NOS (network operating system) has many options for remote access to your network. Check your NOS documentation for these options.

Hardware Requirements

The device most commonly used to connect computers over a public analog phone line is a modem (a contraction of MOdulator/DEModulator). A sending modem converts digital signals from the computer into analog signals that can be transmitted over telephone lines and other analog media. On the receiving end, the modem changes the analog signals back to digital signals. Because telephone lines can be found almost everywhere, this method of remote communication is readily available to everyone with access to a phone line.

Modems change the digital ones and zeros into analog signals that can be transmitted over telephone lines. The pattern of these analog signals encodes the data for transmission to the receiving computer. The receiving modem then takes the analog signals and turns them back into ones and zeros. This method is slower than a completely digital transmission, but data can travel over longer distances with fewer errors.

A modem can be either internal or external. The key difference between the two is the amount of configuration required. You must configure internal modems with an IRQ and an I/O address, as well as a virtual COM port address, to ensure that they function properly. External modems simply hook to a serial port and don’t require nearly as much configuration.

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