BOOK(PDF): Click Here
YOUTUBE VIDEO NOTE AND QUESTION: Click here
NOTE: Click here
If you find any mistakes, please comment so that others can verify and identify the error.
IMPORTANT CHAPTER WISE QUESTION AND ANSWER: Click here
Be Cautious While Copying
A Gentle Warning for Students and Educators
The internet is an incredible tool for learning, but it requires a mindful approach. Take the time to verify, understand, and use the information appropriately. By doing so, you’ll not only safeguard your academic success but also uphold the values of honesty and diligence.
Stay curious, stay careful, and let your pursuit of knowledge be both responsible and rewarding!
📚 Disclaimer & Thanks:
All the credit goes to the original author(s), publisher(s), or content creator(s) of this material. I do not own any rights to this content. This PDF or material is shared only for educational and informational purposes, especially to help students who cannot afford or access it easily.
Special thanks to the person/group who made this content available online. Your contribution is truly appreciated.
If you are the rightful owner of any content and want it to be removed, please contact me. I will respectfully take it down.
सामग्रीको मूल स्वामित्व लेखक, प्रकाशक वा सामग्री सिर्जनाकर्ताको हो। म यसमा कुनैपनि स्वामित्वको दाबी गर्दिन। यो सामग्री केवल शैक्षिक उद्देश्यका लागि मात्र साझा गरिएको हो।
धन्यवाद ती व्यक्ति/समूहलाई जसले यो सामग्री इन्टरनेटमा उपलब्ध गराउन सहयोग गर्नुभयो।
यदि तपाईं यो सामग्रीको कानुनी स्वामी हुनुहुन्छ र यो हटाउनु पर्ने लागेमा कृपया सम्पर्क गर्नुहोस्।
Unit 1: Introduction to Computer Network (6 Hrs)
1.1 Definitions, Uses, Benefits
A computer network is a system of interconnected devices
(like computers, printers, and smartphones) that communicate using protocols (rules
for communication such as TCP/IP, HTTP, etc.).
Uses:
- File and resource sharing (printers, internet).
- Communication (email, video calls, messaging apps).
- Remote access and cloud storage.
- Entertainment like gaming and video streaming.
Benefits:
- Cost-efficient resource sharing.
- Faster and easier communication.
- Centralized data management and backup.
- High flexibility and scalability.
- Supports remote work and collaboration.
1.2 Overview of Network Topologies
Network topology refers to the physical or logical
arrangement of nodes in a network.
- Bus: All devices share a single communication line. Cheap but one failure can
break the whole network.
- Star: All devices connect to a central hub. Common in home networks, easy to
manage.
- Ring: Devices form a closed loop. Data travels in one direction. A break
affects the whole network.
- Mesh: Every node connects to every other node. Reliable but expensive.
- Tree: A hybrid of star and bus; used in campus networks.
- Hybrid: Combines multiple topologies for flexibility.
1.3 Overview of Network Types
- PAN (Personal Area Network): Short-range, e.g., Bluetooth
between phone and speaker.
- LAN (Local Area Network): Small area like an office or home, e.g., Ethernet in a
college lab.
- CAN (Campus Area Network): Covers multiple buildings, like a university
campus.
- MAN (Metropolitan Area Network): Covers a city, e.g., municipal internet
service.
- WAN (Wide Area Network): Covers countries/continents, e.g., the Internet.
By Purpose:
- SAN: Storage Area Network for data centers.
- EPN: Private network for enterprises.
- VPN: Secure access to private networks over public internet.
1.4 Networking Types (Client/Server, P2P)
- Client/Server: Centralized model. The server provides
resources; and clients' requests. Common in businesses. Pros: secure and fast. Cons:
server failure disrupts service.
- Peer-to-Peer (P2P): Each device is both client and server. Used in
file-sharing (e.g., BitTorrent). Pros: scalable and decentralized. Cons: less
secure and bandwidth-heavy.
1.5 Overview of Protocols and Standards
Protocols: Rules for communication.
- Examples: HTTP (web), FTP (file), TCP/IP (internet), SMTP (email).
- Elements: Syntax (format), Semantics (meaning), Timing (synchronization).
Standards:
- Ensure compatibility and reliability.
- De Jure: Official (ISO, IEEE).
- De Facto: Popular use (e.g., Windows file formats).
- Open Standards: Public and free (e.g., HTML, TCP/IP).
- Proprietary Standards: Owned by companies (e.g., Adobe Flash).
1.6 OSI Reference Model
7-layer model for communication from sender to receiver:
1. Physical: Bits transmission.
2. Data Link: Frames, MAC address, error detection.
3. Network: IP addressing, routing.
4. Transport: Reliable delivery (TCP), segmentation.
5. Session: Dialog control (who speaks when).
6. Presentation: Data translation, encryption.
7. Application: User services (HTTP, FTP).
Modular design allows layered troubleshooting and development.
1.7 TCP/IP Model vs OSI
TCP/IP has 4/5 layers:
1. Physical + Data Link (Network Access Layer)
2. Network (Internet Layer)
3. Transport
4. Application
Comparison:
- OSI is theoretical; TCP/IP is practical.
- TCP/IP is used in real-world internet communications.
- Both have layered approaches and similar functions.
1.8 Connection and Connectionless Services
- Connection-Oriented: Like a phone call; setup before data
transfer.
- Reliable, slower, uses TCP.
- Connectionless: Like sending letters; no setup.
- Fast but less reliable, uses UDP.
1.9 Internet, ISPs, Backbone Network
Internet: A global network connecting millions of devices.
ISPs (Internet Service Providers):
- Provide internet access.
- Examples: Worldlink, NTC.
Backbone Network:
- High-capacity data routes (e.g., fiber optic lines).
- Connect ISPs and major networks.
- Examples: SprintLink, NAPs (Network Access Points).
History:
- 1969: ARPANET.
- 1983: TCP/IP became standard.
- 2025: AI, 5G, satellites drive the future.