The Internet

The Internet

1. A network of computer networks and computers using a globally unique address space based on the Internet Protocol and TCP/IP to support public access to email and web pages ect

2. (WWW) World Wide Web is a system of interlinked, hypertext documents accessed via the internet

3. End to end princible

   • Two computers control a communication across the intenet
   • Each computer using the internet should be uniquely identified

4. Packet switching

   • Data packets flow across the internet between two end points that control their communication
   • A message is broken into variable length packets consisting of part of the data, source and destination adress
   • The packets travel independently through the internet backbone, routed on the basis of the destination adress

5. Routers

   • Hosts are computers running applicfations
   • A router is a special switch that recieves packets from one host or router and uses the destination IP address

6. Gateways

   • Connects networks that use different protocols
   • Each network is connected to the internet through a router gateway the gateway overcomes the mismatch between different networks

7. Internet address

   • Each computer on the internet is labeled with a globally unique address known as an internet protocol address
   • The numbering system IPv4 used today allows for 232 different adresses
   • All these unique addresses make up a single logical address space. At a binary level, an IPv4 address consists of 32 bits

8. Domain names/ IP addresses

   • Hierarchical system using abbreviations and names. Examples of top level domain suffixes include arp,mil ,com, edu, gov and country names such as .uk
   • Domain name system DNS. Watch DNS made easy
     • DNS server translates fully qualified domain name into an IP address
     • URI Uniform resource identifier is an identifier for a resource.
       • A URL identifies via its network location
       • A URN identifies a resource from its name
   • A domain name identifies a network of computers whilst a fully qualified domain name uniquely identifies a particular host on this working

9. Client server model

   • Server is software process that provides a service requested by a client software process
   • A client is a software process that requests and uses the services provided by a server
   • A client software process initiates a request for some service from a server software process which responds to that request

10. Protocols

    • FTP Uploading files to a web server
    • Telnet logging into and running software on a remote computer
    • HTTP Hypertext transfer protocol: viewing web pages
    • POP3 downloading personal emails from a webmail server
    • (Secure) SHTTP accessing secure web pages
    • SMTP sending emails

11. TCP/IP

    • 4 layers application, transport, network and link
      • Application
        • Handles the details of a particular network link application
      • Transport
        • Establishes supervises and maintains a connection between two communicating applications one on each host. it ensures a reliable flow of data, detects when errors occur
        • Splits data that the applications wish to send into chunks to fit packets and reassembles recieved packet data in to data for application
      • Network
        • Addresses packets with source and destination IP addresses so that they may be routed through the internet
      • Link
        • Handels all the physical details of interfacing with the cable including the network interface card and a device driver