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COMPUTER

Page 1

History of Internet

  • Introduction: The Internet's roots began in 1969 with ARPANET, connecting UCLA and the University of Utah using 56 kbit/s circuits, financed by the U.S. Department of Defense (DoD).

  • ARPANET: Aimed at connecting university computers and the defense sector.

  • NSFNET: Introduced in the mid-80s by the National Science Foundation (NSF), NSFNET had higher bandwidth but restricted usage to academic research.

  • Emergence of the Internet: As private networks developed in the 1990s, they interconnected with ARPANET and NSFNET, culminating in the formation of the Internet.

  • Web Popularity: The 1990s witnessed a surge in Internet usage, largely due to the advent of the World Wide Web (WWW).

Working of Internet

  • Networking: Computers are interconnected through networks, facilitated by gateways to the Internet backbone.

  • TCP/IP Protocol: The primary communication protocol of the Internet, managing data transmission by breaking it into packets.

    • TCP: Responsible for dividing messages and reassembling them at the destination.

    • IP: Manages addressing, ensuring data packets reach the correct destination.

Uses of Internet

  • E-Commerce, Research, Online Education, E-Governance, E-Reservation, Online Payments, Video Conferencing, Social Networking, and Entertainment.

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Advantages of Internet

  1. Quick access to vast information.

  2. Facilitates easy communication across the globe.

  3. Global connectivity shrinks distances.

  4. Eco-friendly by reducing paper usage.

  5. An excellent advertising platform for businesses.

Disadvantages of Internet

  1. Cyber fraud risks (credit card theft).

  2. Exposure to inappropriate content.

  3. Vulnerability to viruses.

  4. Potential for message interception.

  5. Reliability of information can be questionable.

Internet Governance

  • No Central Authority: The Internet operates without central governance but has organizations to coordinate its development:

    • IAB: Technical oversight of Internet architecture.

    • IETF: Develops communication protocols.

    • IRTF: Focuses on long-term Internet research.

    • InterNIC: Handles registration services.

    • W3C: Sets web standards.

    • ISOC: Advocates for Internet growth.

Page 3

Connecting to the Internet

Dial-up Connection

  • Temporary connection via telephone lines and modems. Requires user login and establishment of connection with an ISP.

Broadband Connection

  • High-speed Internet, always ON, measured in Mbps. Requires a broadband modem. Includes:

    • DSL: Uses telephone wires, distinct types (HDSL, VHDSL, ADSL, SDSL).

    • Cable Modem: Utilizes coaxial cables, faster than DSL with speeds of 1.5 Mbps+.

    • Broadband over Power Line: Utilizes electrical connections for broadband access.

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Wireless Connection

  • Connects using radio links, eliminating the need for physical wires. Includes:

    • Wi-Fi: Facilitates high-speed wireless internet for homes and public spaces.

    • WiMAX: Delivers broadband wirelessly over long distances, supports many users.

    • Mobile Wireless: Lower speed, requires special PC cards.

Connection Types: Advantages and Disadvantages

  • Dial-up:

    • Advantages: Easily available, low cost.

    • Disadvantages: Slower, uses phone lines.

  • Broadband:

    • Advantages: Faster, can use phone lines simultaneously.

    • Disadvantages: Higher cost, not universally available.

  • Wireless:

    • Advantages: No phone line needed, flexible location.

    • Disadvantages: Less secure, potential health concerns.

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Essential Terms

  • ARPANET: First packet-switching network.

  • ISP: Internet Service Provider.

  • Modem: Device converting digital data to analog signals for transmission.

  • Bandwidth: Data carrying capacity of a circuit.

  • TCP/IP: Communication protocol established in 1973 and standardized in 1983.

Popular ISPs in India

  • Data Communication Ltd.

  • MTNL

  • Airtel

  • Reliance

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World Wide Web (WWW)

  • A collection of Internet servers supporting multimedia access to varying protocols. The fastest-growing component of the Internet enabling easy information exchange.

  • Protocols: Rules governing data exchange, including:

    • HTTP: Transmits hypertext over the web.

    • SMTP: Distributes email messages.

    • FTP: Facilitates file transfers.

    • VoIP: Voice communications over IP.

    • POP/IMAP: Email communication protocols.

Attributes of the WWW

  • User-friendly, supports multimedia, fosters interactivity with hyperlinks and frames.

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Web Pages and Websites

  • Web Page: Documents comprising HTML files, creating an interconnected web.

  • Website: A group of related HTML files under a common address (URL).

  • Home Page: The main entry point of a website.

  • Web Portal: Combines links and resources, customizable for users.

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Web Browsers

  • Software to retrieve and display web content. Two types:

    • Text Browsers: Display only text (e.g. Lynx).

    • Graphical Browsers: Display text and graphics (e.g. Chrome, Firefox).

  • Popular Browsers:

    • Netscape: Early 1994 browser influencing market dominance.

    • Internet Explorer: Launched in 1995, became widely prevalent.

    • Safari: Developed by Apple.

    • Firefox: Gained popularity from Mozilla.

    • Google Chrome: Released in 2008, emphasizes speed and efficiency.

Page 9

Web Servers

  • Programs serving HTML pages to users.

Major Web Servers

  • Apache HTTP Server: Most widely used server supporting multiple platforms.

  • IIS: Microsoft’s high-performance server.

  • Lighttpd: Fast and secure open-source server.

  • Sun Java System Web Server: Supports various technologies.

  • Jigsaw Server: Open-source server from W3C.

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Web Address and URL

  • URL: Unique address for each web page, essential for accessing content on the Internet.

Components of URL

  1. Protocol used.

  2. Domain name indicating the host.

  3. Hierarchical path to the resource.

Types of URL

  • Absolute URL: Full path specifications.

  • Relative URL: Based on the current location rather than full path.

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Domain Name and DNS

  • Domain Name: Text representation of an IP address, aiding user navigation.

  • Domain Name System (DNS): Converts domain names to IP addresses, maintaining website identification.

IP Address Characteristics

  1. Unique for each machine.

  2. Global standardization.

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Email and Blogs

  • Email Address: User@Domain format serves as identification for electronic communication.

    • Services: Gmail, Yahoo! Mail, etc.

  • Blogs: Online journals for sharing opinions, often structured to include text, images, and links. Blogs can function as educational tools.

Advantages of Blogs

  1. Flexible timing for updates.

  2. Easy to write and publish.

  3. Reader engagement through commenting.

Disadvantages of Blogs

  1. Potential isolation for bloggers.

  2. Income instability linked to blogging.

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Newsgroups

  • Online forums for discussion on various topics, organized by subject.

Advantages

  1. Structured access compared to mailing lists.

  2. Often features a FAQ for guidance.

Disadvantages

  1. Slower than email for communication.

  2. Risk of unreliable information.

Page 14

HTTP and HTML

  • HTTP: Core protocol for transmitting web data; stateless, independently processes commands.

  • HTML: Language for web page design, structured through tags to present content visually.

Checkpoints

  • Various questions and prompts are included throughout the notes for understanding concepts.