The Internet and Communications (b)

The Internet and Communications (b)

1. Packet Switching

   • Definition
     • the process of delivering packets from on computer system to another using a designated device e.g. switch or router
   • How?
     • Data is split into packets
       • Packets are transmitted over a network, taking different routes to reach its destination
         • When all the packets arrive, the data is reassembled

2. Routing

   • Definition
     • The method of selecting paths along which packets are sent on a computer network
   • Specialist computer systems construct a routing table
     • Specialist Computer Systems
       • Routers
       • Switches
       • Bridges
       • Firewalls
       • Gateways

3. MAC Addresses

   • Media Access Control Address
   • unique hexadecimal number
   • This hexadecimal number is given to any communication device
   • Routing tables store the MAC address of communication devices
   • MAC address is permanent

4. IP Addresses

   • Used by TCP/IP protocol to uniquely identify computer systems on a network
   • IP addresses can change

5. How DNS servers and IP addresses work

   • DNS
     • Domain Name System
       • Definition
         • a distribute database that matches IP addresses to computer system resources
   • HOW?
     • The Computer System sends a request to its DNS server for the IP addresses that is mapped to the domain name that you typed into the address bar
       • DNS server returns the IP address allowing the systems to communicate
         • If not, the local DNS server will pass it on to a higher DNS server

6. HTML - Important?

   • coding of web pages is simplified
     • More can understand the hashtags

7. Cookies

   • Definition
     • Data stored on a computer system
   • allow websites to store a small amount of uniquely identifying data on your computer while visiting the webstite

8. Search Engines

   • Definition
     • an application that can be accessed over the Internet which can be used to search for websites on a particular topic
   • How does it work?
     • An index of topics will be built by bots or crawlers
       • Bots and crawlers will visit websites
         • Bots and crawlers record info about websites