Basics of Internet Concepts_250324_205854.pptx

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1. Introduction to basic internet concepts 1 The Internet, also called “the Net” is a global network of networks. It is a worldwide system of computer networks conceived by the Advanced Research Projects Agency (ARPA) of the U.S. government in 1970. Internet can be used to receive all kinds of information such as text, graphics, voice, video, and computer programs. It can be connected through computer using phone line, cable, DSL, wireless. No one owns Internet, although several organizations the world over collaborate in its functioning and development.

2. Evolution of Internet • he history of Internet can be traced to the launch of Defence Advanced Research Projects Agency (DARPA) by US President Dwight Eisenhower for enhancing military applications and to regain the lead of US in science Intelligent or Semantic Web,Data can be shared and reused across platforms. Blogs, wikis, web services, social networking sites Internet becomes commercialized during the early 1990’s. The ARPANET ceased to exist in 1990. The most significant development in the history of Internet was the invention of World Wide Web (WWW) Packet-switching was introduced to allow networked computers to communicate flawlessly across multiple, geographically dispersed locations. In 1969s, ARPANET was commissioned with 15 nodes and 23. 4

3. Intranet An intranet is a computer network for sharing information, collaboration tools, operational systems, and other computing services within an organization, usually to the exclusion of access by outsiders Uses of Intranet Streamlining everyday activities by making repeated tasks more feasible. Centralizing and managing important information and company data in a single database. Making collaboration easier since information can be shared across the entire network. Providing personalized content to employees based on their role within the company. Improving internal communication by making employee directories, company news and organization charts readily available. Providing fast and easy access to information about company policies, benefits and updates. 3

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5. INTERNET SERVICE PROVIDER (ISP) 5 Organization that provides a myriad of services for accessing, using, or participating in the Internet. Factors to consider when choosing ISP Bandwidth : Data transferring speed provided by ISP Company. Availability : Availiability of Network & performance to its users Cost : Refers pricing of the connection as well as services Network security : It is an important issue related to the network over the Internet. Everyone has its own private information being safe on their servers & nodes. Customer Services : Better Customer service is highly required from an ISP. Location & need for speed : It is an also a important factor, when we looking an Internet provider is the location where we live or work. A better location refers a good level of customers support.

6. Internet Connections 6 There are many ways a personal electronic device can connect to the internet. They all use different hardware and each has a range of connection speeds: Dial- Up (Analog 56K). DSL Cable Wireless Satellite Cellular

7. 1.Dial- Up 7 Dial- up access is cheap but slow. A modem connects to the Internet after the computer dials a phone number. This analog signal is converted to digital via the modem and sent over a land- line serviced by a public telephone network. Telephone lines are variable in quality and the connection can be poor at times. The lines regularly experience interference and this affects the speed. Since a computer or other device shares the same line as the telephone, they can’t be active at the same time. Speed: 28K to 56K

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9. 2. DSL 9 DSL stands for Digital Subscriber Line. It is an internet connection that is always “on”. Uses 2 lines so your phone is not tied up when your computer is connected. There is also no need to dial a phone number to connect. DSL uses a router to transport data. Speed: 128K to 8 Mbps

10. DSL Following are the several versions of DSL technique available today: Asymmetric DSL (ADSL) Symmetric DSL (SDSL) High bit- rate DSL (HDSL) Rate adaptive DSL (RDSL) Very high bit- rate DSL (VDSL) ISDN DSL (IDSL) All of the above mentioned technologies differ in their upload and download speed, bit transfer rate and level of service. 10

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12. 3. Cable 12 Cable provides an internet connection through a cable modem and operates over cable TV lines. There are different speeds depending on if you are uploading data transmissions or downloading. The coaxial cable provides a much greater bandwidth over dial-up or DSL telephone lines. Speed: 512K to 20 Mbp.

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14. 4. Wireless 14 Wireless, or Wi-Fi, does not use telephone lines or cables to connect to the internet. It uses radio frequency. Wireless is also an always on connection and it can be accessed from just about anywhere. Speed: 5 Mbps to 20 Mbps.

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16. 5. Satellite 16 Satellite accesses the internet via a satellite in Earth’s orbit. The enormous distance that a signal travels from earth to satellite and back again, provides a delayed connection compared to cable and DSL. Speed: 12K to 2.0 Mbps

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18. 6. Cellular 18 Cellular technology provides wireless Internet access through cell phones. The speeds vary depending on the provider, but the most common are 3G and 4G speeds. 3G is a term that describes a 3 rd generation cellular network obtaining mobile speeds of around 2.0 Mbps. 4G is the fourth generation of cellular wireless standards. The goal of 4G is to achieve peak mobile speeds of 100 Mbps but the reality is about 21 Mbps currently.

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20. Working of Internet 20 network that uses IP and TCP protocols for The internet is a packet-routing communication. Every device attempting to access the internet is initially linked either physically through cables or wirelessly. Each computer connected to the internet is also assigned a unique IP address that enables the device to be recognized. Each packet is assigned a port number that will connect it to its endpoint. The message is then sent over the internet where it's received by the internet service provider's (ISP) router. The router examines the destination address assigned to each packet and determines where to send it and eventually, the packet reaches the client.

21. Main components of Internet 21 Client or endpoint devices - These can include computers, smartphones, tablets, routers, web servers and IoT devices. Servers - Servers are the computers that provide services or share stored resources with the client devices. Internet protocols - To retrieve the required data on the internet, a set of guidelines and procedures known as protocols must be adhered to as they guarantee accurate and effective data transmission. Common internet protocols include IP, TCP/IP, HTTP, HTTP, Secure (HTTPS) and file transfer protocol. Other protocols, such as Session Initiation Protocol for voice- over IP, Post Office Protocol 3 (POP3) and Internet Message Access Protocol (IMAP) for email are also used.

22. Contd.. 22 IP addresses - IP addresses are used to identify devices on the internet. These can include IPv4 addresses such as 192.168.1.1, which is the default IP address which many router manufacturers use to access a router's interface. IPv4 addresses are shorter than IPv6 addresses, which are designed to handle the increasing number of connected devices. Routers - Routers forward data packets between computer networks. By using routing tables, routers determine the best routes or paths for data transfer between devices. Domain name system - DNS converts human- readable domain names, such as www.example.com, into IP addresses.

23. Contd... 23 Web browsers - Web browsers or search engines -- including Apple Safari, Google Chrome, Microsoft Edge and Mozilla Firefox -- let users access and engage with material on the internet and also decipher and present web pages to them. ISPs - ISPs are companies that provide users with internet connectivity. They operate the infrastructure, including the cables and routers needed to connect users to the global network. Firewalls and security measures - Incoming and outgoing network traffic on the internet is monitored and controlled by different types of security firewalls and security measures. Firewalls safeguard networks and devices against unauthorized internet access, cyber threats and malicious activities. Social media platforms - Social media platforms, such as Facebook, X (formerly known as Twitter) and Instagram, let users connect, share content and communicate with people all over the world.

24. Key features of Internet 24 Worldwide availability - The internet is a global resource that's accessible to everyone. Compatibility with other media types - Due to the standardized protocols and formats that it offers, the internet facilitates compatibility with various media types. Easy accessibility - Web browsers such as Chrome or Firefox are used to access the internet. For end users and developers, these programs are simple to use, comprehend and easy to develop. Affordability - The expenses associated with developing and maintaining internet services are low. However, the costs vary depending on the type of services and providers being used.

25. Security and Internet 25 Large amounts of information, both public and private, are collected across the internet, opening users up to the risk of data breaches and other security threats such as malware infections, ransomware attacks and phishing attempts. Hackers and crackers can break into networks and systems and steal login information or bank and credit card account records. Internet security refers to a set of techniques and methods targeted at safeguarding online activities and transactions. Users can take the following steps to protect their online privacy: Install antivirus and anti malware software on devices and endpoints. Create difficult, varied passwords that are impossible to guess. Use a virtual private network or, at least, a private browsing mode, such as Google Chrome's Incognito window.

26. Contd... 26 Use secure protocols, such as HTTPS, instead of HTTP for online transactions. Make all social media accounts private. Deactivate autofill. Turn off the device's Global Positioning System (GPS). Update cookies so an alert is sent anytime a cookie is installed. Log out of accounts instead of just closing the tab or window. Use caution with spam emails and never open or download content from unknown sources. Use caution when accessing public Wi-Fi or hotspots. Regularly back up important data both offsite and on the cloud.

27. What is a browser? 27 A web browser is an application used to access websites on the Internet. It is software that allows users to access and view content on the World Wide Web. A web browser acts like a translator, taking information from web servers and displaying it to the user as a web page. A web browser gives you access to all platforms available on the internet, enabling you to view texts, images, and videos worldwide. By entering a URL into the search engine, you guide your web browser towards a specific web server. The browser will access that server, fetch the requested information, and display it as a web page. Hence, the main functions of a web browser are to fetch and display web pages and provide an interface for user interaction. It allows people to access information online in a user-friendly experience.

28. Types of web- browsers Desktop Browsers 28 Desktop browsers are a productivity powerhouse, offering complete features and functions for a smooth browsing experience. Compared to their mobile counterparts, desktop browsers provide a wider range of features, such as tabbed browsing, extensions and add- ons, and advanced security. Some popular web browsers suited for the desktop include Google Chrome, Mozilla Firefox, Microsoft Edge, and Safari. While Chrome is lauded for its popular Google services like Gmail and Docs, Firefox provides exceptional security and add- ons. Meanwhile, Edge is fast, and Safari provides a clean browsing experience.

29. Types of web- browsers 29 Mobile Browsers These browsers are designed for a mobile device’s smaller screen and touch interface. Usability and fast loading times are key features of mobile browsers to provide smooth browsing. Safari for iOS is Apple’s built- in mobile browser integrated with Apple services. It is optimized for performance on iPhones and iPads. As for its Android counterpart, Chrome for Android works on Android devices. Like its web browser, its mobile version is synced with Google’s features. These mobile browsers often come pre- installed on mobile devices, but alternatives are available based on users' preferences.

30. Types of web- browsers 30 Embedded Browsers These refer to miniature versions of web browsers embedded into other applications. They enable users to access the web browser without opening a separate window. Hence, they have limited features compared to a complete web browser. Some common examples of embedded browsers are: Email Clients: Many email clients have built- in web browsers for displaying web content within emails, such as interactive buttons or online surveys. Social Media Apps: Social media platforms often embed web browsers so users can view shared links or articles without leaving the app. Gaming Consoles: Modern gaming consoles frequently have built- in web browsers, which allow users to access online features game guides, and connect with other players.

31. Browser Components 31 While the rendering engine plays a central role in the working of a web browser, multiple other components bring to you any web page you access via the internet. Some key components include: User Interface (UI) : You interact with it directly. It includes the address bar, where you enter website addresses, the back and forward buttons for navigation, and the tabs that allow you to open multiple websites simultaneously. Rendering Engine: As discussed, the architect is responsible for building the visual representation of the webpage. Networking Component: It fetches website files (code, images, videos) from web servers worldwide, ensuring all the necessary pieces are delivered to the rendering engine to build the web page. JavaScript Engine: It interprets and executes JavaScript code, allowing webpages to respond to user actions and create dynamic experiences. Security Components: They handle tasks like encrypting data transmissions (HTTPS) and protecting you from malicious websites. Each component plays a unique role and combines a completely functioning web browser.

32. World Wide Web (WWW) 32 WWW works on the client server model. A user computer works as a client which can receive and send data to the server. When a web page is requested by a user, the browser contacts the requested server (where the website is stored) and by fetching and interpreting the requested files, it displays the web page on the computer screen. The whole process takes place in these three steps: Contact to DNS Server: When a user enters a URL into the address bar and hits enter ’’, at first browser contacts the DNS server. A DNS server stores the IP addresses of the server associated with the corresponding domain names. The DNS server takes the domain name from the browser and returns the corresponding IP address to the browser.

33. 2. Contact to Server: After getting the IP address of the server for the requested webpage, browser sends a request to that server for the desired files. 3 Rendering :The entire process followed by a browser from fetching the webpage to displaying it on the screen is called Rendering. 33

34. Search Engines 34 Search engines on the web are sites enriched with facility to search the content stored on other sites. There is difference in the way various search engines work, but they all perform three basic tasks. Finding and selecting full or partial content based on the keywords provided. Maintaining index of the content and referencing to the location they find Allowing users to look for words or combinations of words found in that index. The process begins when a user enters a query statement into the system through the interface provided.

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36. Search engine works by following these steps: 36 Crawling Indexing Processing Queries Ranking Crawling Search engines run automated programs, called "robots" or "spiders" that use the hyperlink structure of the web to "crawl" the pages and documents that make up the World Wide Web. Once a new page is found the spider reads the Content & also checks for Images.

37. Indexing Once a page has been crawled by robots, its contents can be "indexed" - stored in a giant database of search engines called an "index". This index allows the Search Engine to sort all the documents in fractions of a second. This indexed data is stored in encoded format to save space. Contents of index Basic information for document or record like File name / URL / record ID Title or equivalent Size, date, MIME type Full text of item More metadata like Product name, picture ID Category, topic, or subject – Other attributes, for relevance ranking and display 37

38. Processing Queries: When a request for information comes into the search engine, the search engine retrieves all the documents from the index and tries to match them with the query. A match is determined if the term or phrase is found on the page in the manner specified in the query. The search engine finds millions of matching information, so it uses an algorithm to decide in which order to display the results. Ranking: Once the search engine has determined which results are a match for the query, the engine's algorithm runs calculations on each of the results to determine which is most relevant to the given query. They sort these on the results pages in order from most to least relevant so that users can make a choice about which to select. 38

39. Search Engines 39 Type Example Description Conventional library catalog Search by keyword, title, author, etc. Text- based Google, Bing, Yahoo! Search by keywords. Limited search using queries in natural language. Voice- based Google, Bing, Yahoo! Search by keywords. Limited search using queries in natural language. Multimedia QBIC, WebSeek, SaFe Search by visual appearance (shapes, colors,..)

40. Types of Search Engines 40 Crawler-based search engines are those that use automated software agents (called crawlers) that visit a Web site, read the information on the actual site, read the site's meta tags and also follow the links that the site connects to performing indexing on all linked Web sites as well. The crawler returns all that information back to a central depository, where the data is indexed. The crawler will periodically return to the sites to check for any information that has changed. The frequency with which this happens is determined by the administrators of the search engine. Human-powered search engines rely on humans to submit information that is subsequently indexed and catalogued. Only information that is submitted is put into the index. In both cases, when you query a search engine to locate information, you're actually searching through the index that the search engine has created. These indices are giant databases of information that is collected and stored and subsequently searched. This explains why sometimes a search on a commercial search engine, such as Yahoo! or Google, will return results that are, in fact, dead links.

41. What is an IP Address? 41 An IP address, or Internet Protocol address, is a unique string of numbers assigned to each device connected to a computer network that uses the Internet Protocol for communication. It serves as an identifier that allows devices to send and receive data over the network, ensuring that this data reaches the correct destination. IPv4: This is the most common form of IP Address. It consists of four sets of numbers separated by dots. For example, 192.158.1.38. Each set of numbers can range from to 255. This format can support over 4 billion unique addresses. Here’s how the structure is broken down: Four Octets: Each octet represents eight bits, or a byte, and can take a value from to 255. This range is derived from the possible combinations of eight bits (2^8 = 256 combinations).

42. IP Address 42 Example of IPv4 Address: 192.168.1.1 192 is the first octet 168 is the second octet 1 is the third octet 1 is the fourth octet Each part of the IP address can indicate various aspects of the network configuration, from the network itself to the specific device within that network. In most cases, the network part of the address is represented by the first one to three octets, while the remaining section identifies the host (device).

43. IP Address 43 IPv6: IPv6 addresses were created to deal with the shortage of IPv4 addresses. They use 128 bits instead of 32, offering a vastly greater number of possible addresses. These addresses are expressed as eight groups of four hexadecimal digits, each group representing 16 bits. The groups are separated by colons. Example of IPv6 Address: 2001:0db8:85a3:0000:0000:8a2e:0370:7334 Each group (like 2001, 0db8, 85a3, etc.) represents a 16-bit block of the address.

44. HTTP 44 HyperText Transfer Protocol (HTTP) is a protocol using which hypertext is transferred over the Web. Due to its simplicity, HTTP has been the most widely used protocol for data transfer over the Web but the data (i.e. hypertext) exchanged using HTTP isn’t as secure as we would like it to be In fact, hyper- text exchanged using HTTP goes as plain text i.e. anyone between the browser and server can read it relatively easily if one intercepts this exchange of data. The web server delivers the desired data to the user in the form of web pages when the user initiates an HTTP request through their browser. Above the TCP layer lies an application layer protocol called HTTP. It has given web browsers and servers certain standard principles that they can use to talk to one another.

45. HTTPS 45 Hypertext Transfer Protocol Secure (HTTPS) is an extended version of the It is used for secure communication. In HTTPS, the communication protocol is encrypted using Transport Layer Security. HTTPS stands for Hypertext Transfer Protocol Secure. While HTTPS guarantees data security, the HTTP protocol does not provide data security. As a result, HTTPS can be defined as a secure variant of the HTTP protocol. Data can be transferred using this protocol in an encrypted format. In most cases, the HTTPS protocol must be used while entering bank account information. The HTTPS protocol is mostly utilised in situations when entering login credentials is necessary. Modern browsers like Chrome distinguish between the HTTP and HTTPS protocols based on distinct markings.

46. Cookies 46 Cookies are small files of information that a web server generates and sends to a web browser. Web browsers store the cookies they receive for a predetermined period of time, or for the length of a user's session on a website. They attach the relevant cookies to any future requests the user makes of the web server. Web browsers store cookies in a designated file on users' devices. The Google Chrome web browser, for instance, stores all cookies in a file labeled "Cookies." Chrome users can view the cookies stored by the browser by opening developer tools, clicking the "Application" tab, and clicking on "Cookies" in the left side menu.

47. What are cookies used for? 47 User sessions: Cookies help associate website activity with a specific user. A session cookie contains a unique string (a combination of letters and numbers) that matches a user session with relevant data and content for that user. Personalization: Cookies help a website "remember" user actions or user preferences, enabling the website to customize the user's experience. Tracking: Some cookies record what websites users visit. This information is sent to the server that originated the cookie the next time the browser has to load content from that server. With third- party tracking cookies, this process takes place anytime the browser loads a website that uses that tracking service.

48. Email 48 Email messages are composed, delivered, and stored in a multiple step process, which starts with the message s composition. When the user finishes composing the message and sends it, the message is transformed into a standard format: an RFC 2822 formatted message. Afterwards, the message can be transmitted. Using a network connection, the mail client, referred to as a mail user agent (MUA), connects to a mail transfer agent (MTA) operating on the mail server. Contd...

49. The mail client then provides the sender s identity to the server. Next, using the mail server commands, the client sends the recipient list to the mail server. • The client then supplies the message. Once the mail server receives and processes the message, several events occur: recipient server identification, connection establishment, and message transmission. • Using (DNS) services, the sender s mail server determines the mail server(s) for the recipient(s). Then, the server opens up a connection(s) to the recipient mail server(s) and sends the message employing a process similar to that used by the originating client, delivering the message to the recipient(s). 49

50. Firewall A firewall is a collection of hardware and software that, when used together, prevent unauthorized access to a portion of a network. A firewall consists of the following components: Hardware: Firewall hardware typically consists of a separate computer or device dedicated to running the firewall software functions. Software: Firewall software provides a variety of applications. In terms of network security, a firewall provides these security controls through a variety of technologies: Contd... 50

51. Internet Protocol (IP) packet filtering Network address translation (NAT) services SOCKS server Proxy servers for a variety of services such as HTTP, Telnet, FTP, and so forth Mail relay services Split Domain Name System (DNS) Logging Real- time monitoring 51

52. Website 52 Website is a collection of related web pages that may contain text, images, audio and video. The first page of a website is called home page. Each website has specific internet address (URL) that you need to enter in your browser to access a website. Website is hosted on one or more servers and can be accessed by visiting its homepage using a computer network. A website is managed by its owner that can be an individual, company or an organization. A website can be of two types: Static Website Dynamic Website Contd...

53. A static website contains Web pages with fixed content. Each page is coded in HTML and displays the same information to every visitor. Static sites are the most basic type of website and are the easiest to create. A static site can be built by simply creating a few HTML pages and publishing them to a Web server Since static Web pages contain fixed code, the content of each page does not change unless it is man This works well for small websites, but it can make large sites with hundreds or thousands of pages difficult to maintain updated by the webmaster. Contd... 53

54. A dynamic website contains information that changes, depending on the viewer, the time of the day, the time zone, the viewer's native language, and other factors. Dynamic websites contain Web pages that are generated in real- time. These pages include Web scripting code, such as PHP or ASP. When a dynamic page is accessed, the code within the page is parsed on the Web server and the resulting HTML is sent to the client's Web browser. The word "parse" means to analyze an object specifically. 54

55. Most large websites are dynamic, since they are easier to maintain than static websites. This is because static pages each contain unique content, meaning they must be manually opened, edited, and published whenever a change is made. Dynamic websites that access information from a database are also called database- driven websites. Dynamic pages, on the other hand, access information from a database. Therefore, to alter the content of a dynamic page, the webmaster may only need to update a database record. 55

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