Information Technology Reference
In-Depth Information
Dial-Up Internet
In the early days of the Internet, dial-up access was all that was avail-
able. A dial-up connection uses a telephone line to connect to an ISP at
a maximum speed of around 44.8 Kbps. Dial-up connections have many
drawbacks. You cannot use the phone line for telephone calls while you
are connected to the Internet, and the Internet connection is not always
on; you must connect to the Internet when you want to use it, and
then disconnect when you are finished. The speed is very slow (less than
1/100th of a more modern connection, on the average), resulting in
frustrating waits for every operation. A dial-up connection is established
using a
dial-up modem
.
dial-up modem
A device that converts between
analog and digital data so computer data can be
sent over analog phone lines.
Cable Internet
At the other end of the speed spectrum from dial-up is cable Internet
access. Cable is currently the fastest type of commercially available
Internet access for residential customers, theoretically delivering top
speeds of up to 30 Mbps (although most connections top out at around
20 Mbps).
Cable Internet is delivered through the same coaxial cable as the cable
TV programming. You connect a splitter to the cable coming in from the
wall, to allow the cable to go to both your TV and to a
cable modem
(which may be provided by the cable company for a monthly lease fee).
cable modem
A broadband modem designed to
work with a cable Internet connection.
You can also optionally share the Internet connection with other com-
puters in your home or office by using a broadband router. Some cable
modems are dual-purpose units, with a router built in. If you have one of
these, you do not need a separate router.
DSL Internet
Digital subscriber line (DSL)
is a high-speed Internet connection from
your local land-based telephone company. DSL uses the same twisted-
pair cable to provide Internet that it does to provide voice service, with
a splitter used to separate the data and voice signals so you can use them
both at once. This type of DSL has a speed ranging from 256 Kbps to
20 Mbps depending on the distance between the service address and the
phone company's connection box. It can also deliver high-definition TV
and phone service, all on a single line.
digital subscriber line (DSL)
A broadband
Internet technology provided by the telephone
company.
Satellite Internet
Satellite Internet
service uses the same communication satellites that
you learned about earlier in this chapter. Satellite Internet service
involves using a satellite dish for receiving and a satellite transmitter for
sending data.
satellite Internet
A broadband Internet
technology that uses satellites and a transmitter/
receiver to provide Internet access.
Satellite service is not likely to be anyone's first choice as a broadband
Internet connection. It is relatively slow (around 1 Mbps), and suf-
fers from significant
latency
(delay) issues that make it unsuitable for
performance-sensitive online activities like videoconferencing and playing
action-based games. However, satellite is available just about anywhere.
When faced with the choice of dial-up modem connection or satellite,
people who need a broadband connection will go with satellite.
latency
A period of waiting for another compo-
nent to deliver data needed to proceed.
