1. Mr C Johnston ICT Teacher www.computechedu.co.uk
BTEC IT Unit 28 - Lesson 01 How the Internet Works
Mr C Johnston
ICT Teacher

2. Session Objectives
Understand web architecture and components which make up the internet.

3. How Does the Internet Work??

4. What Are the Main Components of the Internet?

5. Once you have watched the video download the vocabulary worksheet and complete the definitions of key internet components.

6. Web Components Hardware Software Protocols
eg web, mail and proxy servers; routers;
Software
eg browser, ;
Protocols
transport and addressing eg TCP/IP;
application layer eg HTTP, HTTPS, SMTP;

7. Web Architecture Internet Service Providers (ISP) Web hosting services
Domain structure
Domain name registrars
Worldwide web
BIOS
Hard
ware

8. The Internet
The internet is simply a network of computer networks made up from clients, servers and interconnection devices.
BIOS
Hard
ware

9. Description… Servers provide services for example host websites,
Clients (pcs, mac, tablets, phones, consoles etc.) access the services using software for example web browser software,
Requests are sent from the software as data packets and have a source and a destination address,
Routers, route the data packets to their destination by passing them across different networks,
Servers reply to the requests sending the required information back in more data packets using the source address,
Routers will again route the data packets to the required client by passing the data packets from network to network.

10. The Web Server
A website needs a home so other people can access it – this is known as a host,
Most common hosts are Web Servers – computers running special software which can handle requests and deliver content to others,
Servers are normally powerful computers with multiple processors, lots of memory and huge storage capacity,
A Web Server in addition requires a permanent internet connection and a static IP address for each site its running.

12. Topic Task Draw a diagram to show how an HTTP request works.
Write a short report which outlines web architecture and the components which allow the internet and websites to function ensure you include:
Components:
hardware eg web, mail and proxy servers; routers;
software eg browser, ;
Web architecture:
Internet Service Providers (ISP) and web hosting services; world wide web
DNS system; domain name and domain name registrars; IP Addresses
BTEC Book – Unit 28 p4 - 6

13. P1 – Outline the web architecture and components which enable internet
and web functionality.
The outline should take the form of a short report which defines the different components requires and a diagram which shows the different stages of a request and the information which passes through them to get it from server to screen

14. Points to Address Ensure that you clearly outline in your report
A clear definition of the world wide web
The role of a web server, services it provides and why it is needed
The role of a mail server, services it provides and why it is needed
The role of a proxy server, services it provides and why it is needed
The role of a router, services it provides and why it is needed
The role of browser software, services it provides and why it is needed
The role of an client, services it provides and why it is needed
The role of an Internet Service Provider (ISP), the typical functions provided and they are required
The role of a web hosting service, the typical features provided and why they are required
The purpose of a domain name along with a diagrams clearly showing there structure
The role of a domain name registrar and why they are needed
The role of DNS, the services provided and why it is needed
Ensure your diagram includes
Client (PC / laptop / tablet), Routers, DNS, ISP(s), webserver, path of data

15. Internet Addressing – TCP/IP - History
In 1983 it was decided that all computers on the net should communicate using a standard protocol,
A protocol is a set of rules – in English we must start sentences with a capital letter and end with a punctuation mark,
Transport Control Protocol / Internet Protocol (TCP/IP) was chosen,
It is made up of 4 layers:
The top level provides the protocols which your applications use e.g. , http, and ftp
The middle layers breaks data up into packets and adds destination and source addresses. They also reassemble at the other end
The bottom layer sends / receives data

16. Internet Addressing – TCP/IP - Explanation
Each computer (both servers and clients) connected to the internet need an address so they can send and receive data,
Internet Protocol states how this address is constructed: A 32 bit binary number spilt into four parts of 8 bits by a full stop,
The parts of the IP address are then decimalised for ease of use.
For example: is
Each computer that is connected to the internet needs a unique registered IP Address,
Your computer is assigned an IP address automatically by your ISP when you connect to the internet.

17. Accessing Web Pages
To access a webpage on a server you need to enter the IP address for the server where the pages live into web browsing software
IP address for Google's server
IP address for Google's server entered into browser and page appears
Is this really the best way to access content on the internet??

18. Domain Names - Overview
The “Domain Name” was invented to make the web more accessible,
Access webpage's using IP addresses would intimidate some people and most would struggle to remember them,
Domain names are a textual way of accessing websites – instead of entering an IP address companies can register their name or a related word and link it to their IP address,
You can register a domain name for as little as 99p for 2 years.
The “Domain Name Service” (DNS) links your IP address and domain name so that either become an address for your site,
Basically DNS is big database listing domain names and their linked IP address. Your ISP contain DNS listings on its servers.

19. Theoretical Example DNS
Domain Name IP
uk.msn.com
In theory a DNS table would look something like this – in practice however they are a lot more complicated!
ntchosting.com.    394    IN      A      

20. Domain Names - Example www.computechedu.co.uk/quiz
“Domain Names” have different parts
This part is the domain name
This part is the top level domain – also known as the extension or suffix
This part is the directory where the web page lives
sales.computechedu.co.uk
help.computechedu.co.uk
These are subdomains of the main domain name - a domain could have many of these

21. Choice #1 – Domain Name
The first choice is what your domain name should be???
The obvious choice is your business name…..
What if its taken or not possible e.g. B&Q???
Something key to do with your business – DIY!!!

22. Choice #2 – Top Level
There are various different domain name extensions which your domain can have,
Typical domain names include:
.com – international company
.org – none profit organisation
.net - network services such as ISPs
.co.uk – UK company
.gov – government
.ac.uk – UK college / university
You can investigate the available extensions for your domain by visiting an Accredited Registrar,
You can only reserve domain names which don’t belong to anyone else - some will not be available due to restrictions.

23. The fee varies depending on extensions and also supplier – its good to shop around,
Registrations last for 2 years before they need to be renewed,
NOMINET.uk are an organisation who handle domain registrations in the UK and issue domain name certificates once applications are processed by the registrars.