Copy of AQA AS Computing Unit 2 - Structure of the Internet

• Understand the structure of the internet
• Understand the difference between the internet, intranet and WEB
• Describe URL's and URI's in networking
• Understand how domains are structured
• Understand how an IP address is broken down
• Understand role of Internet Registers and Registrars
• Understand the role of an ISP.
• Understand the purpose of Domain Name Server.
• Be familiar with the client–server model.
• Be familiar with TCP/IP, FTP, HTTP, HTTPS
• Understand Application Protocols - telnet, POP3 etc..

• Router -are switches that recieve and send packets of data
• It uses IP address of destincation to route it to the right link
• Gateway - special router (on national backbone)
• Allows one network to be connected to another (as they use different link layer protocols)

Difference between Internet and Intranet and WWW

Structure of a packet

Routers are used to allow multiple connections to

form a network (you couldnt connect loads of computers without them!)

Example

A school router will pass packets onto a local router

these are passed on to a regional router

these are passed on to a national router

these are passed on to an international router

and so on until it gets to the local network which is where the router and switch will route it to the destination PC.

another example of a home network

Design of internet

Concept of internet - data packets being sent through cables and networks from a source to a destination.

• Use unique addresses - IP Addresses
• Switches and routers use this IP address when deciding which way to send ROUTE the packets to the destinations
• LIKE POSTCODES!

Internet

Intranet

WWW - world wide web

So how keeps track of all the domain names?

• global network;
• A network of interconnected computer networks / computers;
• using a globally unique address space;
• Packet-switched network;
• using end-to-end communication protocol // Internet Protocol // TCP/IP;
• public network;

Internet - a network of computer networks and computers using unique IP addresses and TCP/IP

• a system of interlinked hypertext documents;
• accessed via the Internet;
• using HTTP protocol (to retrieve webpages);
• Web pages not restricted to intranet;

• a private (computer) network;
• available to a closed community // only within an organisation;
• that uses Internet Protocols;
• to share part of an organisation’s information (with its members);
• USES THE SAME PROTOCOLS AS INTERNET BUT IS PRIVATE

Data

Source Address

Destination

Address

Internet Registries and Registrars

Register and store domain names

each domain like .com has its own seperate registry

This allows us to track IP addresses to domain names - think yellow pages!

Example of a home network

data is broken down into packets and sent

Router

Switch - allows you to join multiple computers together (locally)

How do i get access to the internet?

You get access through an ISP (internet service provider)

A business that sells access to the internet

Objectives

DOMAIN Names and IP Addresses

URL - Uniform Resource Locator

Structure of the Internet

Internet used to use IP Addresses to locate files

192.168.53.124

However as the internet grew this became difficult to remember what each sites location was

Come on DNS

the target for where a resource is on a network

URI - Uniform Resource Identifier

Domain Name servers allow us to use abbreviated names to refer to networks, e.g. 10.220.62.26 can become

st-mary.blackpool.sc.uk

URN - is uniform resource name

• locating a resource by name NOT by location

http://www.microsoft.com/games/index.html

path / location of the resource

Protocol used:

Examples

HTTP - Hypertext Transfer Protocol

FTP - File Transfer Protocol

HTTPS - secure HTTP (banking and other secure shopping)

address of the webserver