1. Introduction to Networks

• Network: A computer network is a collection of two or more interconnected devices (computers, printers, mobiles, servers, etc.) that can communicate and share resources (data, files, hardware, internet).
• Need for Networks:
  • Resource sharing (printers, files, applications).
  • Communication (email, chat, video conferencing).
  • Data sharing and remote access.

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2. Types of Networks

1. PAN (Personal Area Network)
   • Covers a very small area (a few meters).
   • Used for connecting personal devices like smartphones, laptops, printers, Bluetooth devices.
   • Example: Bluetooth or USB tethering.
2. LAN (Local Area Network)
   • Covers a small geographical area (like an office, school, or building).
   • High speed, inexpensive, privately owned.
   • Example: Computer lab network in school.
3. MAN (Metropolitan Area Network)
   • Covers a city or a large campus.
   • Larger than LAN but smaller than WAN.
   • Example: Cable TV network, city-wide Wi-Fi.
4. WAN (Wide Area Network)
   • Covers a very large geographical area (country, continent, or globe).
   • Internet is the largest WAN.
   • Example: Banking network across countries.

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3. Network Devices

1. Modem
   • Converts digital signals (computer) into analog signals (telephone lines) and vice versa.
   • Needed for internet connection over telephone lines.
2. Hub
   • A simple device that connects multiple computers in a network.
   • Broadcasts data to all connected devices (less efficient).
3. Switch
   • Smarter than a hub; forwards data only to the intended device (using MAC address).
   • Improves network efficiency.
4. Repeater
   • Amplifies and regenerates signals to extend the distance of a network.
5. Router
   • Connects multiple networks (LAN to the internet).
   • Uses IP addresses to send data to correct destination.
6. Gateway
   • Acts as a translator between two different networks using different protocols.
   • Example: Connecting LAN with mainframe system.

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4. Network Topologies

1. Star Topology
   • All devices connected to a central hub/switch.
   • Easy to add/remove devices, but if hub fails, whole network fails.
     

1. Bus Topology
   • All devices connected using a single backbone cable.
   • Simple and cheap, but backbone failure crashes the entire network.

1. Tree Topology
   • Hierarchical structure combining star and bus topology.
   • Good for large organizations.

1. Mesh Topology
   • Every device connected to every other device.
   • Very reliable (no single point of failure) but expensive.

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5. Introduction to Internet

• Internet: A global network of interconnected networks, allowing data communication and resource sharing.
• Key Terms:
  • URL (Uniform Resource Locator): Address of a resource on the internet (e.g., https://www.cbse.gov.in).
  • WWW (World Wide Web): A collection of interlinked hypertext documents accessed via the internet.

Applications of Internet:

• Web: Browsing information on websites.
• Email: Sending/receiving electronic messages.
• Chat: Real-time text communication.
• VoIP (Voice over Internet Protocol): Making voice/video calls over the internet (e.g., WhatsApp, Skype).

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6. Website

• Website: A collection of related web pages hosted on a web server, accessible via a domain name (e.g., www.itxperts.co.in).
• Webpage: A single document/page on a website.

Difference between Website and Webpage

Website	Webpage
Collection of related pages	A single page of a website
Example: www.wikipedia.org	Example: Wikipedia’s “India” page

Static vs Dynamic Webpages

• Static Page: Fixed content, same for all users. Example: About Us page.
• Dynamic Page: Content changes based on user interaction or database. Example: Facebook feed, Amazon product page.

Web Server and Hosting

• Web Server: A computer that stores websites and delivers them to users on request (e.g., Apache, Nginx).
• Web Hosting: Renting space on a server to store a website and make it accessible on the internet.

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7. Web Browsers

• Web Browser: Software used to access and view web pages.
• Common Browsers: Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, Opera.

Browser Features:

1. Settings – Customize homepage, privacy, security, download preferences.
2. Add-ons & Plug-ins – Extra tools to enhance functionality (e.g., Ad-blocker, Flash Player, Grammarly).
3. Cookies – Small text files stored by websites on user’s computer to remember preferences and track activity.

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✅ Summary Points

• Network → PAN, LAN, MAN, WAN.
• Devices → Modem, Hub, Switch, Repeater, Router, Gateway.
• Topologies → Star, Bus, Tree, Mesh.
• Internet → URL, WWW, Applications (Web, Email, Chat, VoIP).
• Website vs Webpage → Static vs Dynamic.
• Web Server & Hosting.
• Browsers → Settings, Add-ons, Plug-ins, Cookies.

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Practice Questions

A. Multiple Choice Questions (MCQs)

1. Which of the following is the largest network?
   a) LAN
   b) MAN
   c) WAN
   d) PAN
2. Which device connects different networks and directs data using IP addresses?
   a) Hub
   b) Switch
   c) Router
   d) Repeater
3. Which topology is most reliable but also most expensive?
   a) Bus
   b) Star
   c) Tree
   d) Mesh
4. The address https://www.cbse.gov.in is an example of:
   a) IP Address
   b) URL
   c) Domain Name System
   d) Protocol
5. Cookies are used to:
   a) Improve internet speed
   b) Store user preferences and activity
   c) Connect networks
   d) Provide virus protection

Answer Key: 1–c, 2–c, 3–d, 4–b, 5–b

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B. Very Short Answer Questions (1 Mark)

1. Define PAN with an example.
2. Name any two commonly used web browsers.
3. What does VoIP stand for?
4. Write one difference between static and dynamic web pages.
5. Which device is used to boost network signals?

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C. Short Answer Questions (2–3 Marks)

1. Differentiate between Hub and Switch.
2. Write two advantages and disadvantages of Bus topology.
3. What is a Web Server? Give two examples.
4. Write two differences between a website and a webpage.
5. Explain any two applications of the internet.

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D. Long Answer Questions (4–5 Marks)

1. Explain PAN, LAN, MAN, and WAN with examples.
2. Discuss different network devices with their functions.
3. Draw neat diagrams and explain Star, Bus, and Mesh topologies.
4. What is a website? Explain static and dynamic webpages with suitable examples.
5. What are web browsers? Explain features like settings, add-ons, plug-ins, and cookies.