Data Communication basic Study Notes


  • Data communications are the transfer of data from one device to another via some form of transmission medium.
  • A data communications system must transmit data to the correct destination in an accurate and timely manner.
  • The five components that make up a data communications system are the message, sender, receiver, medium, and protocol.
  • Text, numbers, images, audio, and video are different forms of information.
  • Data flow between two devices can occur in one of three ways: simplex, half-duplex, or full-duplex.
  • A network is a set of communication devices connected by media links.
  • In a point-to-point connection, two and only two devices are connected by a dedicated link. In a multipoint connection, three or more devices share a link.
  • Topology refers to the physical or logical arrangement of a network. Devices may be arranged in a mesh, star, bus, or ring topology.
  • A network can be categorized as a local area network or a wide area network.
  • A LAN is a data communication system within a building, plant, or campus, or between nearby buildings.
  • A WAN is a data communication system spanning states, countries, or the whole world.
  • An internet is a network of networks.
  • The Internet is a collection of many separate networks.
  • There are local, regional, national, and international Internet service providers.
  • A protocol is a set of rules that govern data communication; the key elements of a protocol are syntax, semantics, and timing.
  • Standards are necessary to ensure that products from different manufacturers can
    work together as expected.
  • The ISO, ITD-T, ANSI, IEEE, and EIA are some of the organizations involved
    in standards creation.
  • Forums are special-interest groups that quickly evaluate and standardize new
  • A Request for Comment is an idea or concept that is a precursor to an Internet


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