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It is commonly referred as the ‘Net’. It is a network of networks and the most important component of
                 today’s Communication  and  Information Technology.  It  connects  computers and  networks of various
                 individuals, Organizations, Universities, Companies, Government Departments, etc.

                 It has facilitated e-Commerce, e-Governance, e-Banking, e-Shopping, e-Reservation, e-Chatting,
                 e-Conferencing,  e-Choupal,  e-Learning,  e-mail, online entertainment  activities, web  chatting,  video-
                 conferencing, online reservation of tickets of railways, airlines, buses, etc., on-line transactions, online
                 examinations, getting online information on different topics through search engines, broadcasting of
                 various television programs.

                 Media of Communication

                 Transfer of data for exchanging the information takes place through media can be broadly categorized
                 into two types:

                 Wired/Guided

                 It includes communication that takes place with the help of a solid or wired medium like:

                 l  Ethernet Cable                         l  Co-Axial Cable

                 l  Optical Fiber Cable

                 Ethernet Cable
                 Ethernet is a data link technology for local area network. It was invented by

                 an electrical engineer named ‘Robert Metcalfe’ from United States. Ethernet
                 cable refers to CAT5, CAT6 cable which is connected to an Ethernet card to
                 a computer.
                 Such cables commonly provide transmission speed of 100–1000 Mbps. Ethernet cable can be categorized

                 into Straight Through Ethernet Cable and Ethernet Crossover Cable.

                               plastic jacket       Co-axial Cable
                                 dielectric insulator  It consists of a single conductor surrounded by a circular insulation

                                                    layer and a conductive shield. Such cables have a transmission rate
                                                    of 100 Mbps with a bandwidth up to 400 Mhz.

                                                    There are two types of co-axial cable: a ‘75 Ω’ standard cable, that
                 metallic shield                    are used in the cable TV industry and ‘52 Ω’ cable that are used in
                                                    high speed internet broadband networks. Such cables are commonly
                                centre core
                                                    used in LAN.

                 Fiber Optics
                 This type of cable is used mainly in larger networks in which the data are
                 transferred through electromagnetic waves. One fiber of such cable can
                 support over 30,000 telephone lines at a time.







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