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  2. 2. Basic concepts of computer networksand communicationsDefine computer networks is a system of interconnected computers andperipheral devices.For example, it may connect computers,printers, scanners and cameras
  3. 3. Define computer communications is about the transfer of information from asender, across a distance, to a receiver.Using electricity, radio waves or light,information and data in the form of codes aretransmitted through a physical medium such aswire, cable, or even the atmosphere.The information that is transmitted (sent) can betext, voice, sound, video, graphics and images,or a combination of all these, which we callmultimedia.
  4. 4. The importanceof computernetworks andcommunicationsOnlineeducationE-bankingLong DistancecommunicationsE-business
  5. 5. Online education With a network connections, online education is madepossible. Students at any location around the world canparticipate in an online classroom, download tutorialquestions and submit their assignments.E-business Is refers to conducting business transactions on theinternet, not only limited to buying and selling butalso servicing customers and collaborating withbusiness partners.
  6. 6. E-banking handles all types of banking transactions likeaccount management, fund transfer and paymentsprimarily over the internet.Long Distance communications is made easy via network availability. Communication is possible via voice, text or video.
  7. 7. Types of computer networkWide Area Network(WAN)Metropolitan AreaNetwork(MAN)Local Areanetwork(LAN)
  8. 8. Metropolitan Area Network (MAN) can be defined as a group of computers andnetwork devices connected together within a largephysical area.WANis the largest network of all network types. The Internet is the largest WAN in the world. WAN generally covers large distances such asstates, countries or continents.
  9. 9. Local Area network (LAN) is a group of computers and network devicesconnected together, usually within the same building. It is the smallest network compared to the other twonetworks. The simplest form of LAN is to connect twocomputers together. Inexpensive hardware used in LAN previouslyinclude twisted pair, coaxial cables and the higherend is fiber optic or wireless
  10. 10. Wide Area Network (WAN)o WAN is a group of MANs or LANs or the mixture of both networks.o WANis the largest network of all network types.The Internet is the largestWANin the world.o WAN generally covers large distances such as states, countries or continents.o A device called a router is needed to connect the MANs and LANs all over a largephysical area.o A router is a special networking device that connects two or more differentnetworks and keeps data flowing between them.
  11. 11. Types Network ArchitectureClient/Server Peer- to -peer
  12. 12. Client/server is a network in which the shared files and applications arestored in the server but network users (clients) can stillstore files on their individual PCs.Peer-to-peer a network with all the nodes acting as both servers andclients. A PC can access files located on another PC andcan also provide files to other PCs.
  13. 13. 3 types of network topologyBus topologyRing topologyStar topology
  14. 14. Bus topology consists of a single central cable to which all computersand other devices connectRing topology consists of all computers and other devices that areconnected in a loopStar topologyconsists of a central host which acts as the centre, and allnodes connect to the host.
  15. 15. Types of network communicationstechnologyinternet extranet intranet
  16. 16. Internet is the worldwide, publicly accessible system of interconnectedcomputer networks that transmit data by packet switching usingthe standard Internet Protocol (IP).Extranet is a private network that uses Internet protocols, networkconnectivity, and possibly the public telecommunication systemto securely share part of a business’s information or operationswith suppliers, vendors, partners, customers or other businesses.Intranet is an internal network that uses Internet technologies and it is asmall version of the Internet that exists within an organisation.
  17. 17. Devices needed in computercommunications networkNetworkinterfaceCard(NIC)WirelessNetworkInterfaceCardModem(internal andexternal)Hub /switch Router
  18. 18. FunctionsNetwork interface Card (NIC) is an adapter card or PC card that enables the computerto access the networkWireless Network Interface Card is a network card that provides wireless datatransmissionModem (internal and external) There are two types of modem, internal modem andexternal modem.An internal modem only works instand-alone computers.
  19. 19. Hub /switch is a common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN.Router is a communications device that connects multiplecomputers or other routers together and transmits datato the correct destination
  20. 20. MediumTypes of CablesShieldedTwistedPair(STP)Fibre OpticCableUnshieldedTwistedPair(UTP)