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1.3.1e The Internet

What is the Internet?

The Internet is a publicly accessible wide area network which covers the whole world.

Most of the Internet uses the client-server model:

The user's web browser connects to the web server and requests web page files
The server responds by sending the files to the user's device
The browser displays the files as a web page

Internet vs WWW

The Internet and world wide web are not the same thing.

The Internet is the network infrastructure

The world wide web is the content stored on it

Domain Name System (DNS)

When visiting a website, your browser needs the IP address of the web server.

People remember website names as URLs like:

But computers do not understand names. They use IP addresses, which are numbers like:

151.101.192.81
185.194.90.26

The domain name system (DNS) servers contain tables of web addresses and the IP address associated with each one.

Example of Using DNS to Look Up an IP Address

The user types in, or clicks on, a URL in their web browser.

For example, www.bbc.co.uk
Example of Using DNS to Look Up an IP Address

The web browser transfers the URL to a domain name system server.
Example of Using DNS to Look Up an IP Address

The domain name system will look through a list of the URLs it has stored. If it finds the URL, it will have an IP address associated with it.

This is a very simplified example. DNS comprises of many servers.
Example of Using DNS to Look Up an IP Address

The IP address is then returned to the web browser.
Example of Using DNS to Look Up an IP Address

Now the web browser has the IP address of the web server, it can connect to it and request the web pages and files it needs.

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The Cloud

Storage and processing is carried out on a server, which could be anywhere in the world, and accessed via the Internet. Examples of cloud storage include Google Drive, Microsoft OneDrive, and Apple iCloud.