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  • Networks
    • Computer networks
      • LAN / local area network
        • A computer network where computers are geographically close together
      • WAN/ wide  area network
        • A network computers are geographically far apart.
      • World Wide Web~ Is  an application that uses the internet
      • Uniform resource locator ~ the address that can be entered into the address bar to locate a website
      • Each website consists of a number of websites developed using a web authorising language such as HTML
        • Hypertext markup language ~ the language used to define the structure of websites; it is often combined with CSS and JavaScript to create hypermedia applications presented to users via browser software for the World Wide Web
      • To allow the websites to be accessed using the internet , they require a communication protocol known as http ( hypertext transfer protocol)
      • The intranet is similar to the internet, but is managed by an organisation and only authorised users, with a username and password can access the content
      • The internet of things (LoT)describes the impact of the internet of how we live and work.
    • Network communications technology
      • Wi-Fi
        • WiFi connections use radio waves and a wireless router
        • Devices with a built in wireless adapter can connect to a WiFi network
        • Advantages of using a WiFi network is that there is no need for cabling.
        • Disadvantage is the limited distance on how far the signal can travel and variations on the signal strength depending on proximity to a wireless router.
      • Bluetooth
        • Uses short-range wireless technology to connect two devices together
        • For  the devices to begin ransferring data between each other they have to be synchronised or paired
        • Since the devices communicate directly with each other there is no need to have a router
      • Optical fibre
        • Consists of a bundle of glass strands, each strand carries one data signal, which means many data signals can be sent at one time in the bundle.
        • Data is transmitted as pluses of light
        • Advantages of using glass is that signals (or data) cannot be interfered - it is very secure
        • Disadvantage is that it requires the use of repeaters for data to travel over large distances
      • Mobile communication technology
        • 4G  mobile-phone technology is capable of high speed data access access and high-quality video streaming  using wireless technology on a global scale
    • Network resources
      • Network interface cards
        • ~ A NIC is an electronic circuit board built into a computer to allow it to be connected to a network                 ~it allows each computer to communicatewith the file server and the other computers on the network         ~it has a port to allow a network cable to be attached        ~portable computers such as laptops are supplied with a strand with a standard wireless network interface card. (WNIC)
      • Network cables
        • ~ a network cable physically connects to a computer network         ~generally cables are made of copper and data travels along the cables to and from the file server.
      • Switch
        • ~A switch allows a large  number of computers on a network to be connected     ~it checks the destination of data it receives and ensures it is forwarded to the intended computer.
      • Router
        • ~This is a hardware device that connects a number of networks together by either able or wireless.             ~it examines data as it passes, and forwards the data using the most appropriate route to its destination.
    • Network topologies
      • Bus network
        • In this network computers are connected to a main cable known as a back bone
        • Data can travel in both directions along the backbone.
        • To add  a new computer to a bus network its cable is attached to the backbone
      • Star network
        • Computers are connected by there own cable to a file server
        • All data on the network must pass through the file server
        • An additional computer to be added by attaching it (using its own  cable ) to the file server.
      • Ring network
        • Each computer is directly connected to two other adjacent computers to for a ring
        • All data travels in on direction by visiting each computer in turn until it reaches its intended destination.
        • To add a new computer to the network the cable between two existing computers has to be broken and each part of the broken cable attached to the new computers
      • Advantages and disadvantages of networking
        • advantages = users can save their work on the file server and retrieve it on any other computer within the network         ~expensive hardware devices .e.g. laser printers can share by all computers on the network
          • Installing software and updates once onto the file server allows all computers to access software quickly
        • Disadvantages = a software virus can quickly spend  across the network, affecting all user data and the software   ~when a large number of users are logged onto a network ,access speeds can be slow.
          • The setup costs can be expensive as additional hardware e,.g. File servers, network interface cards, switches and routers, has to be purchased.


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