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Computer Science 2210

Internet Principles of Operation

Paper-1

Internet Principles of Operation

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:



IP Addresses:

• It stands for Internet Protocol Addresses.
• It a unique identifier that every device on the internet has.
• It represents the device location and allows these devices to communicate over the internet.
• Without IP addresses, accurate data communication and transfer over the internet will not be possible.
• An IP address is assigned to your device by ISP/network when you connect to the internet for a session.
• An IP address is like a home address that helps in the successful delivery of packages.
• Therefore, contrary to the MAC address, IP addresses change each time your device is connected to the internet.

Example of an IP Address:



URL:

• It stands for Uniform Resource Locator.
• It is an address that allows the world wide web to identify and load the requested web page in the browser.

Example of a URL:


https://www.olevelacademy.com/

• A URL has three parts; https:// is the access protocol, www.olevelacademy.com is the domain name and anything written after that will be the path or file name. If nothing is written then it will take you to the homepage of the website.

Cookies:

• Cookies are text files saved on the web server's request on the user's machine by a browser.
• It can only be read by the website that created it and can store a limited amount of data.
• Some websites add a unique identification code in the cookie to store data in their database avoiding cookie's size limitation.
• These are not malware, viruses or any other programs that can perform actions.
• You can easily disable these from your browser settings.

Uses of Cookies:

• To maintain and store on a website, user preferences.
• To collect user behavior analytics.
• To store shopping cart items.
• To show relevant ads.
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