Networks and Topologies

• What is LAN?


  Local area network.
• What are the properties of LAN?


  • Covers a small geographic area (often a single site)
  • Cables and hardware are owned by network owners
• What are some places LAN may be used?


  Schools, offices, and homes.
• What is WAN?


  Wide area network.
• What are the properties of WAN?


  • Covers a large geographical area (different sites, or between towns and countries)
  • Infrastructure is owned by different people (like the internet)
• Where is WAN used?


  Big businesses (such as the bank), and the internet.
• What are some LAN hardware?


  • Network interface card (NIC)
  • Switch
  • Router
  • Wireless access point (WAP)
• What is a NIC?


  A network interface card - it allows device to connect to network by setting up data packets in the format needed for network.
• What does the switch do?


  It connects devices on a LAN together - it sends data to the correct device using MAC addresses.
• What does the router do?


  Transmits data packets between networks (for example, from homes to the internet) - it receives and sends packets and uses routing tables to direct packets to correct device on most efficient paths.
• What does the WAP do?

  Allows devices to connect wirelessly to a network.
• What is an ethernet cable?


  A wired connection of a copper cable sending data using electrical current.
• What is a fibre optic cable?


  A wired connection of glass cable sending data using light.
• What are the properties of fibre optic cables compared to ethernet cables?


  • They are faster
  • However, they are more expensive.
• What is a client-server network?


  One central, powerful server computer with all other client devices connected to it.
• What is a client?


  Computer the user is using - asks for tasks to be carried out by the server.
• What is a server?


  A device that receives and carries out requests from clients such as printing.
• How are files stored in a client-server network?


  They are stored centrally so they can be accessed from any computer.
• How is back up done in a client-server network?


  It is done by server so automatic and reliable.
• How is the security in a client-server network?


  It is managed and updated centrally so is reliable.
• How is the cost of client-server networks?


  High, as server hardware is expensive, and specialist staff is needed.
• What are some examples of client-server networks?


  Schools, large offices where lots of computers are used, web servers.
• How are web servers an example of a client-server network?


  Websites are stored in web servers centrally, so other devices (clients) can request and view pages.
• What is a peer-to-peer network?


  A network where there is no central computer in charge - computers are equal to each other and connected so they can share files and resources.
• How are files stored in a peer-to-peer network?

  They are stored on individual machines, therefore it is needed to use the same computer every time to access files.
• How is back up done in a peer-to-peer network?


  It is done by each individual user, and may not be reliable.
• How is security in peer-to-peer networks?


  Security is managed and updated by each individual user, and may not be reliable.
• How is the cost in peer-to-peer networks?


  They are cheaper as no specialist staff are needed.
• What are examples of peer-to-peer networks?


  Homes, and offices where fewer computers are used.
• What is the internet?


  A worldwide collection of computer networks connected together, giving access to the world wide web (web pages).
• What does WWW stand for?


  World wide web.
• What does URL stand for?


  Universal resource locator.
• What is an URL?


  An address you type into a browser to go to a website.
• What does DNS stand for?


  Domain name server.
• What is DNS?


  A server that contains a list of URLs - the URL typed into a browser is sent to the DNS and converted to the right IP address.
• What happens if the URL is not found in the DNS?


  It is sent to other DNS to check - if no result is found, error message is returned.
• What is hosting?


  A web server storing your website so other can access it - it costs money and often provides other services such as back up or security.
• What is the cloud?


  Storing data on remote servers rather than your own hardware.
• What are some advantages of using the cloud?


  • Increased storage
  • Access from anywhere
  • Easy to share data
• What are some disadvantages of using the cloud?


  • It requires working internet connection
  • There may be issues regarding privacy and security