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280 Part Two Information Technology Infrastructure

typical Internet connection speed in 2000 was 56 kilobits per second, but today
more than 68 percent of the 239 million U.S. Internet users have high-speed
broadband connections provided by telephone and cable TV companies running
at 1 to 15 million bits per second. The cost for this service has fallen exponen-
tially, from 25 cents per kilobit in 2000 to a tiny fraction of a cent today.
Increasingly, voice and data communication, as well as Internet access, are
taking place over broadband wireless platforms, such as cell phones, mobile
handheld devices, and PCs in wireless networks. In a few years, more than half
the Internet users in the United States will use smartphones and mobile netbooks
to access the Internet. In 2012, 122 million Americans (50% of all Internet users)
accessed the Internet through mobile devices, and this number is expected to
grow to 135 million by 2015 (eMarketer, 2012).

WHAT IS A COMPUTER NETWORK?

If you had to connect the computers for two or more employees together
in the same office, you would need a computer network. Exactly what is a
network? In its simplest form, a network consists of two or more connected
computers. Figure 7.1 illustrates the major hardware, software, and transmis-
sion components used in a simple network: a client computer and a dedicated
server computer, network interfaces, a connection medium, network operating
system software, and either a hub or a switch.
Each computer on the network contains a network interface device to link
the computer to the network. The connection medium for linking network
components can be a telephone wire, coaxial cable, or radio signal in the case of
cell phone and wireless local area networks (Wi-Fi networks).

FIGURE 7.1 COMPONENTS OF A SIMPLE COMPUTER NETWORK

Illustrated here is a very simple computer network, consisting of computers, a network operating system (NOS) residing on a dedicated
server computer, cable (wiring) connecting the devices, switches, and a router.

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