Network Technologies

• Computer networks


  LAN and WAN
• Network


  • A number of computers linked together using either cable or wireless technology
• LAN (Local Area Network)


  A network spread over a small geographical area such as a building
• WAN (Wide Area Network)


  A network spread over a large geographical area on a global scale and requires a telecommunications link to all computers on the network to communicate
• World Wide Web


  An application that uses the internet
• Internet


  An example of a wide area network (WAN)
• Website


  Has a unique address, known as its URL (Uniform Resource Locator)
• Website


  • Consists of a number of webpages developed using a web authoring language such as HTML (Hypertext Markup Language)
  • Webpages are interconnected using hyperlinks, and the first page is called the home page
• HTTP (Hypertext Transfer Protocol)


  A communications protocol that allows websites to be accessed using the internet
• Intranet


  Similar to the internet, but is managed by an organisation and only authorised users, with a username and password, can access the content
• Internet of Things (IoT)


  Describes the impact of the internet on how we live and work
• IoT


  • Any device that can communicate using Wi-Fi technology is included
• Wi-Fi (Wireless Fidelity)


  • Uses radio waves and a wireless router
  • Devices with a built-in wireless adapter can connect to a Wi-Fi network
• Wi-Fi


  • Advantage: no need for cabling
  • Disadvantage: limited distance and variations in signal strength depending on proximity to the wireless router
• Bluetooth


  • Short-range wireless technology to connect two devices together
  • Devices have to be synchronised or paired to begin transferring data
• Bluetooth


  • No need for a router as devices communicate directly with each other
• Optical fibre


  • Consists of a bundle of glass strands; each strand carries one data signal, so many data signals can be sent at one time in the bundle
  • Data is transmitted as pulses of light
• Optical fibre


  • Disadvantage: requires the use of repeaters for data to travel long distances
  • Advantage: signals cannot be interfered with
• Mobile communication technology


  • Capable of high-speed data access
  • Fully supports wireless World Wide Web with little or no limitations
  • More reliable and has greater speeds than previous mobile-phone technology
• Mobile communication technology


  • Allows users to watch television programmes on their mobile phones in HD format
• HTTP (Hypertext Transfer Protocol)


  A protocol used by the World Wide Web that defines how messages are formatted and transmitted by web servers
• WLAN (Wireless Local Area Network)


  A wireless medium that allows devices to connect and communicate using radio waves
• Router


  A hardware device that connects a number of networks together by either cable or wireless to allow for data transmission
• Bluetooth


  A short-range wireless technology that allows two devices to connect for the purpose of communication
• Optical fibre


  A technology that uses very thin glass strands to send data at very fast transmission speeds
• Network interface card (NIC)


  • An electronic circuit board built into a computer to allow it to be connected to a network
  • Allows each computer to communicate with the file server and the other computers on the network
  • Has a port to allow a network cable to be attached
• NIC


  • Portable computers such as laptops are supplied with a standard wireless network interface card (WNIC)
• Network cables


  • Physically connect a computer to a network
  • Generally made of copper and the data travels along the cables to and from the file server
• Switch


  • A hardware device that allows a large number of computers on a network to be connected
  • Checks the destination of data it receives and ensures it is forwarded to the intended computer
• Router


  • A hardware device that connects a number of networks together by either cable or wireless
  • Examines data as it passes, and forwards the data using the most appropriate route to its destination
  • IP addresses are used to determine the route the data travels on
• Bus network


  • Computers are connected to a main cable known as a backbone
  • Data can travel in both directions along the backbone
  • To add a new computer, its cable is attached to the backbone
• Star network


  • Computers are connected by their own cable to a file server
  • All data on the network must pass through the file server
  • An additional computer can be added by attaching its own cable to the file server
• Ring network


  • Each computer is directly connected to two other adjacent computers to form a ring
  • All data travels in one direction by visiting each computer in turn until it reaches its intended destination
  • To add a new computer, the cable between two existing computers has to be broken and each part attached to the new computer
• Cyber crime


  Using a computer to commit a crime, such as stealing data or money
• Hacking


  Gaining unauthorised access to a computer with the intent of corrupting or stealing data
• Malware


  Malicious software that is unintentionally downloaded onto a computer by a user
• Spamming


  Sending junk emails to users, for example adverts for products
• Phishing


  Sending emails that, when opened, appear to be from a reliable source asking the user to update their personal information
• This information is then used by hackers for the purpose of identity theft
• Data encryption


  The process of scrambling data using a key before it is transmitted onto a network