network

network

1. topnology

   • bus
     • advantages
       • cheap
       • easy to install
     • disavantages
       • more computers mean more collesions
       • high chance of collision
   • star
     • advantages
       • not a single collison
       • easy to add new computers
     • disavantages
       • failure of hub or switch is catastrophic
       • expensive

2. topnolgy

   • mesh
     • advantages
       • zero faliure
       • multiple transmissions can happen at some time
     • disadvantages
       • expensive
       • lots of useless connections
   • ring
     • disavantages
       • one faulty wire or computer will result in faliure
     • advantages
       • no collisions
       • number of computers does not affect the spped

3. tcp/ip layers

   • Application Layer
     • Provides applications services to users and programs
   • Transport Layer
     • Handles data-consistency functions (Error Checking)
   • Network Layer
     • Provides network addressing and routing (ip addresses)
   • Data Link Layer
     • Prepares and corrects data to be passed to the physical layer.
   • Physical Layer
     • Transmits and receives bits

4. DNS

   • Every computer on the Internet is identified by its IP address
   • DNS (Domain Name System) is a system to store Domain Names (bbc.co.uk or google.com) and lookup their IP addresses.
   • This is fine for computers, but hard for humans
   • When you type a web address into a browser, your ISP (internet service provider) sends the domain name to its DNS server, which returns the IP address
   • DNS is essentially a large address book.