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other. Thus, the information or message which is shared by each device is stored on their
respective workstations (computers). If, due to some reason (hardware crash, etc.), the data
gets corrupted and, thus, becomes unavailable on one computer, a copy of the same data
can be accessed from another workstation for future use. This leads to smooth functioning
and further processing without disruption.
(e) Central Storage of Data: Files can be stored on a central node (the file server) that can
be shared and made available to each and every user in an organization. With centralized
processing, data is stored and retrieved from a single central location. Thus, there is no
duplication of data and almost no data redundancy.

8.3 EVOLUTION OF NETWORK

The network did not evolve in a single day; rather, it took decades to become more powerful,
efficient and reliable. The network has passed through several stages which are described below:
• ARPANET (Advanced Research Project Agency Network): ARPANET, which was jointly
designed and named by the Advanced Research Projects Agency (ARPA) and US Department
of Defence (DoD), was the first network and came into existence in 1969. It was a project that
connected a handful of computers at different universities and US DoD for sharing of data and
messages and playing long-distance games, and socializing with people to share their views.
• NSFNET (National Science Federation Network): In the mid-80’s, another federal agency,
NSFNET (National Science Federation Network), created a new network which was more capable
than ARPANET. Its main aim was to use network only for academic research and not for any private
business activity. Later, many private companies combined their own private networks with
ARPANET and NSFNET to make a more capable and broad network—the Internet. It is the internet
that links two or more networks to make a large network for sharing of information and messages.

ARPANET + NSFNET + PRIVATE NETWORKS = INTERNET

1995 NSF Net
1984 ARPANET 1986 NSF
1969 terminates its Today more than
has more than
ARPANET 1,000 individual connects NSF net network on the 1996 Internet2 is 550 million hosts
to ARPANET and
becomes Internet and founded connect to the
functional computers linked becomes known resumes status as Internet
as hosts as the Internet
research network Computer Networks
Fig. 8.3: Evolution of Internet
8.3