Transcript How The Internet Works

BTEC IT Unit 28 - Lesson 01
How the Internet Works
Mr C Johnston
ICT Teacher
www.computechedu.co.uk
Session Objectives
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Understand web architecture and components which make
up the internet.
How Does the
Internet Work??
What Are the Main
Components of the Internet?
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Once you have watched the video download the vocabulary
worksheet and complete the definitions of key internet
components.
Web Components
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Hardware
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Software
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eg web, mail and proxy servers; routers;
eg browser, email;
Protocols
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transport and addressing eg TCP/IP;
application layer eg HTTP, HTTPS, SMTP;
Web Architecture
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Internet Service Providers (ISP)
Web hosting services
Domain structure
Domain name registrars
Worldwide web
The Internet
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The internet is simply a network of computer networks made
up from clients, servers and interconnection devices.
Description…
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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.
The Web Server
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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.
Topic Task
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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:
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Components:
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hardware eg web, mail and proxy servers; routers;
software eg browser, email;
Web architecture:
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Internet Service Providers (ISP) and web hosting services; world wide web
DNS system; domain name and domain name registrars; IP Addresses
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BTEC Book – Unit 28 p4 - 6
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
Points to Address
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Ensure that you clearly outline in your report
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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 email 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
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Client (PC / laptop / tablet), Routers, DNS, ISP(s), webserver, path of data
Internet Addressing –
TCP/IP - History
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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:
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The top level provides the protocols which your applications use e.g.
email, 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
Internet Addressing –
TCP/IP - Explanation
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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.
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For example: 10110010.00101000.00000011.01011000
is 178.40.3.88
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.
Accessing Web Pages
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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??
Domain Names - Overview
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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.
Theoretical Example DNS
Domain Name
IP
www.google.co.uk
209.85.229.104
www.bbc.co.uk
212.58.246.90
uk.msn.com
213.199.164.110
www.virginmedia.com
212.250.162.12
www.facebook.com
69.63.181.12
In theory a DNS table would look something like this – in
practice however they are a lot more complicated!
ntchosting.com.
394
IN
A
216.65.1.250
Domain Names - Example
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“Domain Names” have different parts
www.computechedu.co.uk/quiz
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
Choice #1 – Domain Name
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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???
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Something key to do with your business – DIY!!!
Choice #2 – Top Level
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There are various different domain name extensions which
your domain can have,
Typical domain names include:
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.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.
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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.