Internet Principles of Operation

Internet:

• The Internet can be defined as the interconnection of computer systems.

• It utilizes the TCP/IP protocol.

• It can be accessed using 3G, modem, broadband, etc.

• The Internet is accessible to everyone worldwide and contains billions of web pages and tons of information.

• Information on the web (internet) can be accessed via a search engine.

• Hyperlinks are used to browse webpages whereas files (video, audio, text, etc.)can be retrieved or shared by downloading and uploading respectively.

• Today, the internet is also widely used for communication purposes.

Working of the Internet:

• The TCP/IP protocol makes the retrieval and transmission of information possible.

• When you send a request it goes through the network to the DNS (domain name servers).

• The DNS then points the request in the right direction and it reaches its targetted server.

• Once the request has been received by the server, it can send back a response to the computer system that sent the request.

• The response sent by the server can take a completely new path.

• The internet is a powerful tool and one major reason for it is its flexible approach to data transfer.

Browser:

• It is a web application that enables internet users to access various web pages.

• It is responsible for translating the basic HTML code to allow internet users to see videos, images, audio, hyperlinks, etc.

• When a user enters a URL in the browser, it requests the web server for the information, the web server then displays the requested information on the computer screen in a browser application.

• The most commonly used browsers are as under:

- Mozilla Firefox

- Google Chrome

- Internet Explorer

- Safari

• You can either go to a webpage by directly entering the URL if you know it or you can click on links n different webpages to navigate to your desired web page e.g. use of a search engine like google.

Typical Features of a Browser Toolbar:

• It has a ‘Home’ button that allows you to go to the first page that you started off with the internet.

• It has a ‘Bookmark’ or ‘Favorite’ feature, that allows you to save webpages to access them immediately later.

• It also allows you to directly print web pages.

• It allows you to track, monitor or remove your web history.

• It allows you to go to a previous page using the ‘back’ button or go forward.

Internet Servers:

• The machines on the Internet can be divided into two types i.e. clients and servers.

• Servers are machines that provide services to other machines such as FTP servers etc.

• On the contrary, clients (user machines) are the machines that are connected to get these services offered by servers.

• For example, if you use Google to search your query you are using your machine which acts as a client whereas Google has multiple machines that are fulfilling your request and acting as a server.

• Any machine can be a ‘server’ or a ‘client’ or ‘both’.

Internet Service Provider (ISP):

• Internet Service Provider (ISP) can be defined as a company that provides the Internet connection to businesses and individuals.

• ISP generally takes a monthly fee to provide an internet connection.

• The monthly fee is usually based on the speed of the internet as well as the bandwidth provided.

• The Internet Service Provider usually sets up a user account with a password and username.

• Some ISPs also offer web building, emails, hosting, etc.

• ISPs have become common in the 1990s prior to that Internet access was limited to government agencies and universities etc.

Hypertext Transfer Protocol (Http):

• The Http or Hypertext Transfer Protocol as its name suggests is a protocol i.e. used for transmitting messages or data files over www (world wide web).

• Any protocol can be defined as a set of rules.

• When you browse websites using the browser you are in fact using this protocol.

• Today, you might notice the use of https more than Http.

• Https is actually the secure and encrypted version of this protocol.

• It is a crucial protocol when browsing websites and it cannot be ignored.

• Beside it, another important protocol is HTML that deals with the formatting and display of the webpages.

Http identifies the following methods to understand the required action:

• HEAD - without the response body, it asks about the GET request

• GET - request with a response body the specified source presentation

• POST - submits data to convert it from HTML to the identified source form

• PUT – it uploads specified source’s representation

• DELETE – removes the source specified

• TRACE – allows the user to see changes by servers to the specified request by echoing it back

• OPTIONS – it checks web servers functionality for a specified URL by returning HTTP methods

• CONNECT – it converts the connection to TCP/IP tunnel to provide encrypted communication by facilitating SSL via an unencrypted Http proxy

HTML Structure and Presentation:

• HTML (Hypertext Markup Language) is the language used to create web pages.

• The browser is responsible for the interpretation of HTML pages.

• There are two types of HTML; structure and presentation.

• The HTML structure is responsible for defining the structural markup as well as the semantics of the HTML pages.

• Whereas, what we see in the web browser is called HTML presentation i.e. multimedia use and appearance.

• The HTML presentation is also known as ‘style’.

• Both HTML structure and presentation should be written separately i.e. the developer should have an HTML doc and a CSS (Cascading Style Sheet) that deals with the presentation of the webpage.

MAC Addresses:

• It stands for Media Access Control Addresses.

• It is a 48-bit (6 hex-digit groups)  unique value that helps in the identification of the actual device on the internet.

• The MAC address remains the same even when you connect to the internet from any location.

• It can be found inside your device’s NIC (network interface card).

Example of a MAC Address: