1.3.2 Wired & Wireless Networks, Protocols & Layers

• What is a coaxial cable?

  A piece of transmission media made of a single copper wire surrounded by a plastic layer for insulation and a metallic mesh which provides shielding from outside interference.
• What are ‘twisted pair’ cables?

  Cables containing four pairs of copper wires which are twisted together to reduce internal interference and transmit electrical signals as 1s and 0s.
• What are the advantages of standard Ethernet cables?

  • Cheaper to buy and install
  • More stable than wireless connections
  • Acceptable option for short distance use
• What are some disadvantages of standard Ethernet cables?

  • Data transfer is slower than other physical media
  • Signal degenerates over long distances
  • More prone to signal disturbances
• What is a fibre optic cable?

  A cable made of flexible glass threads that transmits data using light signals.
• What are some advantages of a fibre optic cable?

  • Very fast data transfer
  • Less prone to signal disturbances
  • Performs well long distance
• What are some disadvantages of a fibre optic cable?

  • Expensive to buy and set up
  • Connections are costly and timely to expand
• What is Wi-Fi?

  Media transmission which uses radio frequencies to wirelessly transmit data.
• What are some advantages of Wi-Fi?

  • Multiple users can access the network
  • Increased mobility (40-100m range)
  • High bandwidth
• What are some disadvantages of Wi-Fi?

  • More devices connected means speed of individual connections is decreased
  • Strength of connectivity is reduced when users move away from the access point
• What is Bluetooth?

  Media transmission which uses radio frequencies to wirelessly transmit data.
• What are some advantages of Bluetooth?

  • Low cost
  • Use little power
  • Reduced interference
• What are some disadvantages of Bluetooth?

  • Small range (10m)
  • Low bandwidth
  • Limits number of devices that can be connected at one time
  • Data transfer is slower
• Which factor affecting the performance of a network is described as 'data arrives corrupted, resulting in it being resent. The signal quality of wireless is dependent on the range of the device'?

  Error rate.
• Why is encryption used across networks?

  To secure data e.g bank details so they cannot be intercepted.
• What is a network protocol?

  A set of rules for data transmission.
• What is a network standard?

  A set of requirements for hardware/software to interact across different products.
• What is a MAC address?

  A network identifier unique to a device which cannot be changed.
• Where and how are MAC addresses normally used?

  Mainly by Ethernet protocol on LANs to direct data to the right device.
• When are IP addresses used?

  When sending data between TCP/IP networks.
• IPv4

  • uses 32 bits
  • 4 groups of 8 bits each given as a denary number
  • limited number of addresses compared to IPv6
• IPv6

  • uses 128 bits
  • 8 groups of 4 hexadecimal numbers
  • created due to the increasing number of devices needing unique IP addresses
• What is TCP?

  Transmission Control Protocol - defines how devices connect on a network and how data is sent and delivered via packets.
• What is IP?

  Internet Protocol - responsible for directing packets to their destination along a network.
• What is HTTP?

  Hyper Text Transfer Protocol - used by web browsers to access websites and communicate with web servers.
• What is HTTPS?

  HTTP Secure - a more secure version of HTTP which encrypts all information sent and received.
• What is FTP?

  File Transfer Protocol - used to access, edit and move files between devices on a network.
• What is POP?

  Post Office Protocol - used to retrieve emails from a server: the server holds the email until you download it, at which point it is deleted from the server.
• What is IMAP?

  Internet Message Access Protocol - used to retrieve emails from a server: the server holds the email until you delete it and you only download a copy. Used by most web-based mail clients.
• What is SMTP?

  Simple Mail Transfer Protocol - used to send emails and transfer them between servers.
• What is TCP/IP?

  The protocol which dictates how data is sent between networks.
• What is a layer?

  A group of protocols which have similar functions.
• What are the advantages of using layers?

  • It breaks network communication into manageable pieces which helps developers concentrate on one area of a network without having to worry about the others.
  • As layers are self-contained, they can be changed without the other layers being affected.
  • Having standards for each layer forces companies to make compatible, universal hardware and software, so different brands will work with each other in similar ways.
• How is data transferred between layers?

  Data can only be passed between adjacent layers.
• What are the four layers?

  Application, transport, network, link.