Networks Autumn Term 2

Networks Autumn Term 2

1. Encryption

   • Code plain text into cipher text

2. Networks

3. The Internet

   • Group of inter-connected networks
   • World Wide Web
     • Collection of web pages
     • Stored on computers all over the world
     • No owner
     • No central storage
     • Accessed via the Internet
     • Invented by Tim Berners-Lee
   • URL (Uniform Resource Locator)
     • This is a web address
     • All web addresses are unique
   • Domain Names
     • Top level domains
       • eg .uk
   • Packet Switching
     • Breaking data into packets and routing independently
   • Need a router to access

4. Connectivity

   • Bandwidth
     • The amount of data that can be carried at a time
   • Connection speeds
     • Measured in Mbps
   • Wireless Connectivity
     • Must be close to a wifi hotspot or router
     • Slower than wired connection
     • Greater security risk
     • No need to be physically connected
     • Interference from walls and furniture
     • Can connect mobile devices
   • Buffering
     • Occurs when a movie or music sound track plays faster than it downloads
     • Computer stores some of the file in a buffer until it can begin playing the whole thing

5. Topologies

   • Local Area Network (LAN)
     • Small
     • You are responsible for connections
   • Wide Area Network (WAN)
     • Large
     • 3rd Party - Responsible for connections
   • Network Interface Card (NIC)
     • Each device needs a NIC to connect to a network
   • Bus Topology
     • Single main cable
       • If main cable breaks the whole network stops working
   • Star Topology
     • Connected to a hub or switch
       • If the hub fails the network goes down
       • If one device fails the others keep working
   • Ring Topology
   • Mesh Topology
     • Very reliable
     • Costly
   • Hybrid Topology
     • A mix of different topologies
     • Often used in large networks