COMMUNICATION TECHNOLOGIES
2.2 INTERNET PRINCIPLES

This section looks at what the internet actually is, who is in control of the internet and a overview of the overall structure.

WWW. Vs INTERNET

Remember that the World Wide Web and the internet are two different things. The world wide Web is the protocols, language and webpages we access, whereas the internet is the network that provides a medium for the transfer of data.

WHAT IS  THE INTERNET

The internet is simply a computer network that has grown and grown and is now the largest WAN available to the public all over the world. Underground cables all over the world carry data across the internet. When someone creates a webpage, the computer or server that holds/hosts the page is made available to the public and and address is provide on how to access the page. The internet is the network and components that provide a means for the data transfer.

Whilst various data transfer medium are used the internet still predominantly uses cables. When you access the internet from your mobile phone data service the data will travel from your phone to the nearest receiving mast and then the rest of the journey for the data will be done via cables, even laid under the oceans throughout the world.

SEARCH ENGINES

A search engine is what you are using when you type a question in to google or any other search provider through your browser. Google became so successful when two young engineers Larry Page and Sergey Brin created a page ranking algorithm that helps return relevant results extremely fast. 

WEB BROWSERS

A web browser is the application software we use to view webpages. Web browsers provide a front-end with user friendly features such as scroll bars, refresh and navigation buttons and work back-end to send and receive page requests along with interpreting the HTML that webpage are predominantly written in. Google Chrome and Microsoft Edge are examples of web-browser software. When you type a web address, normally in the bar at the top of the browse you are using the URL.

WHAT IS A URL

A URL or Uniform Resource Locator is the address of a webpage, the URL for the homepage of this website is www.computersciencecafe.com. The structure of a url can be broken up into 5 main parts, looking at the url of this page the parts would be:

PART 1 - PROTOCOL: https: - This refers to the protocol used the main two protocols are HTTP and HTTPS
PART 2 - DOMAIN NAME: computersciencecafe.com - This could be further divided into TLD (Top Level Domain) and SLD (Second Level Domain)
PART 3 - PATH OR SUB-DIRECTORY: /resources/internetprinciples - This refers to where there page requested is saved
PART 4 - QUERY: ? Used to provided dynamic webpages with custom features for the user.
PART 5: PARAMETERS - Parameters show further breakdown of the query returned

Check out doepud and click on Anatomy of a URL for more information on URLs.

HTTP VS HTTPS

HTTP(Hypertext transfer Protocol) is the protocol/set of rules used by the World Wide Web to transmit data between clients and servers. HTTPS(Hypertext Transfer Protocol Secure) is an extended version of HTTP and as the name suggests it adds an extra layer of security protocols encrypting data transmissions and uses SSL or TLS security protocols.

COOKIES

Cookies are like the evidence left on the sofa after eating a cookie, you leave crumbs. In the same way, when you visit a webpage a crumb or rather small pieces of data are left on your computer, these small pieces of data are later used for reasons such as:

• Tracking your preferences
• Holding items in your shopping cart
• Saving login details so autofill can be used
• Session data​
  

SESSION DATA

Sessions are a period of time that a user is logged into or using a system, A session could start and end with the user logging in and out or could be ended by a pre-determined time-out. Sessions store temporary data to make the user interaction more fluent such as access rights, user profiles and form details.

WHAT IS AN IP ADDRESS

When connected to the internet you will have two IP addresses,  a public IP address and a private IP address. Your internet service provider will issue you with a public IP address and your home/company router will issue you with a private IP address.

Many IP addresses are classed as Version 4 or V4, these are 32 bit (4 x 1 byte)IP addresses that you will see split into 4 sections, each representing a denery value of binary, for example:

192.16.254.1
or in binary:  11000000.00010000.11111110.00000001

With IP V4 being a 32 bit IP address this means that there are only 4294967296 possible unique representations, although part of this problem is solved in IP addressing protocols there was still a need to expand this value so IP V6 is now in use which uses 48 bit (6 x 1 byte) addresses.

HOW THE INTERNET WORKS

The internet is a collection of smaller networks that are inter connected to create the largest Wide Area Network, the internet that is now accessible globally. The internet is not owned by anyone and any computer can form part of the internet. The World Wide Web uses the internet as a means of data transfer of webpages, the internet provides the structure, cabling and hardware to route data to its destination. Nearly all internet data travels via cables, these cables are installed globally and even under oceans, this is starting to change as technologies such a Starlink are starting to be used to transfer data.

WHAT IS A VPN

When your computer is connected to the internet you have an allocated IP address, this address provides your physical location on the internet network, this is needs so when you request data or webpages they can arrive at your computer/location. If you want to hide your physical location, for example you are on holiday and want to access a webpage that is only normally available to people in your country, then a VPN (Virtually Private Network) is a solution to this. When you connect to a VPN you are connecting to a computer based in your chosen location, when you request a webpage you send the request to the VPN computer and then the VPN computer will request the page for you and then forward the page to you. By masking your IP address it is keeping your internet interactions more private.

​VPNs also provide a layer of security by masking your IP and through encrypting data and through a process of tunnelling.

WHAT IS AN API

An Application Programming Interface or API is a program that is created to help fetch data from one point to another, the concept is it is smart to fetch the parameters requested. The API is an intermediate program that allows communication between software from different developers. 

THE JOURNEY

You are in the classroom and decide to request the webpage www.howstuffworks.com

TASK: Create an info-graph on software such as Canva to illustrate the journey of requesting the webpage, receiving the webpage and the data transfer in-between. In your info-graph consider the following components that might be used for this journey.

Router
Access point
Wireless technology
​Cat 5 Cables
​Optical Cables
Proxy Server
​IP Address

Web Browser
URL
Packet switching
ISP
Hubs
Repeaters
Packet Header​

NEXT: DATA TRANSFER PRINCIPLES

---

COMING SOON

ADVANCED IP ADDRESSING (A-LEVEL ONY)

NetID and HostID 
The NetID is a unique ID given to a network amongst other networks . The HostID is a unique ID given to a machine on a network. ​

Class D and Class E 
There are two more classes that are reserved. But we do not need to discuss class D or E at this level. 

COMING SOON

NEXT: DATA TRANSFER PRINCIPLES