1.4 Wired and Wireless Networks In this unit you will cover…

3. The Internet LOs To define and explain the internet To absolutely definitely know the difference between Internet and WWW To explain the purpose of DNS To explain the purpose of hosting To explain the cloud

The Internet

The Internet - What is the internet? - Where does the internet live? - Who controls the internet?

The Internet The internet does not live in one place The internet is not controlled by any one person or country The internet is not Google Let’s go back in time…

A History Lesson The year is 1969 and the United States Army has started to use computers to do super important army stuff They’ve got networks at each base, already allowing them to share resources within each base America is a pretty big place though, with bases all over the country, they wanted a way to link them all… Thus, the internet was born!

A History Lesson So what were they doing? They were connecting networks together We already know of this concept as a WAN This was the first instance of connecting multiple networks together

The Internet The idea of connecting networks together grew and spread globally, now people were able to communicate all over the world using computers. Here’s the all important definition that you absolutely need to remember: The internet is a global computer network made up of interconnected networks.

WWWWWWWWWW So, what’s the world wide web if it’s not the internet? The internet was great for beardy academic types; using it to share academic data but it wasn’t of much use to the everyday person An everyday person

World Wide Web Just such a beardy academic person was Tim Berners-Lee, a British scientist working at CERN in Switzerland. In 1989 he decided that there should be a better, consistent and friendlier way to share information on the internet. Tim (Sir Tim now)’s invention was the web page. Specifically, he invented http, html and the web browser

HTML The web remains mostly the same today Web pages are made of HTML code HyperText Markup Language HTML is a set of instructions in the form of tags that a web browser understands The tags instruct the browser exactly how the page should appear HTML is a standard – you should know what a standard is by now!

HTML Look at this demonstration of HTML… Now write down a definition for HTML

HTTP A protocol was created to control the transfer of web pages HTTP – HyperText Transfer Protocol A computer requests a web page from a web server The web server sends the web page to the client computer This is all done using IP Addresses, which we’re all experts on now…

DNS If websites are requested using IP addresses, how come you don’t have to type an IP address in every time you want Google or Netflix? You only have to look at phone numbers to realise how rubbish this would be – how many phone numbers can you remember at one time?

TASK - DNS What websites do these IP addresses belong to? 212.58.244.66 176.32.108.186 216.58.208.99 Now the other way around! (use http://whois.domaintools.com) IP Address Website http://www.gov.uk http://www.channel4.com http://www.converse.com

DNS Instead of normal people like you and I having to remember all of the IP addresses, we created giant phone books on the internet This is called DNS – Domain Name Service The pretty, friendly Domain Name (e.g. www.google.com or www.bbc.co.uk) is a lie! It’s just there to help us, it’s not actually where the website lives

DNS When your computer requests a website (e.g., www.google.com), it must find out the IP address that www.google.com actually lives at The request hits a DNS Server, the DNS Server looks through its list for “google.com”, if it finds it, it’ll give the IP address back to your computer If it doesn’t know it, it’ll ask another DNS server

Not found. Try over there Request www.google.com Request: www.google.com Sends HTML to client address 216.58.208.99 Client Request: www.google.com Response: 216.58.208.99 Not found. Try over there DNS Server DNS Server

DNS Hopefully now you should be able to write down a good definition for what DNS is AND Bullet point the separate steps that happen when your computer requests a web page

Hosting Even though the internet doesn’t live in one specific place, our websites still have to live somewhere! They are stored on web servers A web server is a server that can communicate using HTTP, receiving requests from and sending HTML to clients These web servers host websites

Hosting Any computer can be a web server with the correct software People often pay for web hosting in data centres – the servers there are maintained by other people and the user is guaranteed a quality of service Data centres can also offer a more reliable internet connection with the appropriate bandwidth and speed to support high internet traffic Data centres may also offer additional security from web attacks

Amazon even put a datacentre in a lorry Hosting A typical datacentre Amazon even put a datacentre in a lorry

The Cloud With all of these massive and powerful datacentres, a phenomena has started to take over the world…. The cloud! In simplest terms; the cloud is where services and data are stored and provided remotely over the internet Examples of cloud that you use daily (probably) are: Office 365, iCloud, Google Drive, Spotify, Apple Music, Sky Q They’re all services that rely entirely on an internet connection

The Cloud NEGATIVE POSITIVE Some people love the cloud and some don’t… “I don’t know where my stuff is!” “I can access my files from anywhere!” “What if my internet goes down?” “It’s more reliable than storing it myself” “What if I lose my password?” “I can do more with my data in the cloud” “What if somebody gets into my account?” “I don’t need to spend as much on storage”