Computer Science

Computer Science

1. Lesson 1 - Introduction to networks

   • LAN
     • Local Area Network
     • A network in a small area/single organisation.
   • WAN
     • Wide Area Network
     • A network in a large area.
   • Advantages
     • you can use the same username and password on all the computers.
     • You can access your files on all the computers.
   • Disadvantages
     • If one computer in the network gets a virus, all the computers in the network get it as well.
     • It is very expensive to set up.

2. Lesson 2 - Network Topologies

   • Star Topology
     • Advantages
       • Low chance of failure
       • No collisions (fast)
     • Disadvantages
       • Expensive
       • Depends on a switch
   • Ring Topology
     • Advantages
       • Cheap to install
       • No collisions
     • Disadvantages
       • High chance of catastrophic failure
       • Difficult to expand
   • Bus Topology
     • Advantages
       • Cheap to install
     • Disadvantages
       • High chance of catastrophic failure
       • Lots of collisions
       • Slows down as more computers are added

3. Lesson 3-Network Addressing

   • An IP Address
     • An IP Address is a unique value assigned to every computer in a network and is used to identify it.
     • Messages on a network have an IP Address attached, which is how a computer knows whether or not keep the message.
     • The internet is to big for all of the computers to have individual IP Adresses so networks have oall the same.

4. Lesson 5- The internet

   • The internet is arranged in a mesh topology
     • You need to find a route.
       • Routes have "costs"
         • To transmit the data, the lowest "costing" available route is found.
     • data is sent through this mesh in packets.

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