Unit 2: Computer Networking | NEB Class 12 Computer Science Notes
Based on Latest Syllabus 2080 | Complete Networking Concepts for HSEB Examination
Updated according to latest syllabus of 2080 | Includes diagrams and detailed explanations
📡 Introduction — In the past, people used pigeons to send messages over long distances. Later, inventions such as telegrams, telegraphs, and telephones brought remarkable changes in telecommunication.
Communication
Telecommunication
Tele = long distance | Communication = exchange of ideas, views, and information
Thus, communication is the exchange of data and information between a sender and receiver through a medium by following common rules.
Telecommunication is the art of communicating over a distance.
Examples: Telephone, Radio, Television
Thus, communication is the exchange of data and information between a sender and receiver through a medium by following common rules.
Telecommunication is the art of communicating over a distance.
Examples: Telephone, Radio, Television
Basic Communication System
Sender
(Source)
Medium
(Channel)
Receiver
(Sink)
Data | Protocol (Rules)
Basic Elements of Communication
Sender (Source)
Creates and sends the message
Creates and sends the message
Receiver (Sink)
Receives the message
Receives the message
Medium
Carries the message
Carries the message
Data
Information being transferred
Information being transferred
Protocol
Rules used for communication
Rules used for communication
Modes of Communication
Simplex Mode
Communication occurs in only one direction.
Sender only sends and receiver only receives.
Examples: Radio, Television
Half Duplex Mode
Communication occurs in both directions.
Only one device can send data at a time.
Example: Walkie-talkie
Full Duplex Mode
Communication occurs in both directions simultaneously.
Both can send and receive at the same time.
Examples: Mobile phones, Telephone
Data Communication
Definition
After the invention of microcomputers in the 1980s, computers and telephone (Internet) lines were used to send and receive data.
Data Communication: The process of sending and receiving data between computers from one location to another.
Data Communication: The process of sending and receiving data between computers from one location to another.
Computer Network
Definition
A computer network is a group of interconnected computers connected through wired or wireless media to share hardware, software, and other resources.
The concept of connected computers sharing resources is called Networking.
The concept of connected computers sharing resources is called Networking.
Computer Network Structure
Computer A
Server/Switch
Computer B
Printer
Storage
Shared Resources: Printer, Storage, Internet
Transmission Media
Wired Media (Guided)
Twisted Pair Cable
Most common, used in telephone networks. Two types: UTP and STP.
Most common, used in telephone networks. Two types: UTP and STP.
Coaxial Cable
Used in cable TV, has better shielding than twisted pair.
Used in cable TV, has better shielding than twisted pair.
Fibre Optic Cable
Uses light signals, very high speed, immune to interference.
Uses light signals, very high speed, immune to interference.
Wireless Media (Unguided)
Radio Waves
Used in Wi-Fi, Bluetooth, mobile communication.
Used in Wi-Fi, Bluetooth, mobile communication.
Microwaves
Line-of-sight communication, used in satellite links.
Line-of-sight communication, used in satellite links.
Satellite
Long-distance communication using satellites in orbit.
Long-distance communication using satellites in orbit.
Infrared
Short-range communication (remote controls).
Short-range communication (remote controls).
Advantages of Computer Network
Hardware Sharing – Expensive devices like printers can be shared
Software Sharing – Programs can be accessed from remote computers
Centralized Control – All computers can be monitored centrally
Fast Communication – Messages and data transferred quickly
Backup and Recovery – Data backup maintained regularly
Flexible Access – Authorized users can access files remotely
Workgroup Computing – Multiple users can work together
Disadvantages of Computer Network
Virus Transfer – Viruses and malware spread easily
Less Reliable – Failure of one computer may affect others
Security Issues – Unauthorized access may occur
Expensive Setup – Networking devices and cables are costly
Need Technical Manpower – Skilled professionals required
Quick Comparison: Communication Modes
| Mode | Direction | Example |
|---|---|---|
| Simplex | One direction only | Radio, Television |
| Half Duplex | Both directions (one at a time) | Walkie-talkie |
| Full Duplex | Both directions simultaneously | Mobile phone, Telephone |
Key Points Summary
Computer Network: Interconnected computers sharing resources
Simplex: One-way communication
Half Duplex: Two-way but one at a time
Full Duplex: Two-way simultaneous
Transmission Media: Wired (Twisted Pair, Coaxial, Fiber) and Wireless (Radio, Microwave, Satellite)
Frequently Asked Questions (HSEB Pattern)
What is a computer network? Write its advantages.
A computer network is a group of interconnected computers sharing resources. Advantages: hardware sharing, software sharing, centralized control, fast communication, backup, flexible access, workgroup computing.
Differentiate between Simplex, Half Duplex, and Full Duplex.
Simplex: one-way (Radio). Half Duplex: two-way but one at a time (Walkie-talkie). Full Duplex: two-way simultaneous (Mobile phone).
What are the different types of transmission media?
Wired: Twisted Pair Cable, Coaxial Cable, Fiber Optic Cable. Wireless: Radio Waves, Microwaves, Satellite, Infrared.
Write any four disadvantages of computer network.
Virus transfer, less reliable, security issues, expensive setup, need technical manpower.
Quick Revision Card
Simplex = One-way (Radio, TV)
Half Duplex = Two-way alternately (Walkie-talkie)
Full Duplex = Two-way simultaneous (Mobile)
Wired Media = Twisted Pair, Coaxial, Fiber
Wireless Media = Radio, Microwave, Satellite
Types of Network, Architecture & Transmission Media | NEB Class 12 Computer Science
Based on Latest Syllabus 2080 | LAN, MAN, WAN, Peer-to-Peer, Client-Server, Guided & Unguided Media
Updated according to latest syllabus of 2080 | Includes comparison tables and diagrams
Types of Network (Based on Geographical Area)
LAN (Local Area Network)
Covers a small geographical area such as Room, Building, School, Office.
Media: Twisted pair cable, Coaxial cable, Fibre optics
✓ Cheap to establish
✓ Fast data transmission
✓ High security, Easy to manage
✗ Limited area coverage
✗ Connects fewer computers
MAN (Metropolitan Area Network)
Covers City, District, Village. Connects multiple LANs together.
Media: Wired and Wireless
✓ Covers larger area than LAN
✓ Connects more computers
✓ Supports wired and wireless
✗ More expensive than LAN
✗ Slower than LAN
✗ Complex management
WAN (Wide Area Network)
Covers Countries, Continents, Entire world. Example: Internet
Media: Mostly Wireless
✓ Largest geographical coverage
✓ Connects many computers
✓ Long-distance communication
✗ Very expensive
✗ Slowest network type
✗ Requires skilled manpower
LAN, MAN and WAN Comparison
| Features | LAN | MAN | WAN |
|---|---|---|---|
| Area Covered | Room, Building | City, Village | Country, World |
| Media | Wired | Wired/Wireless | Mostly Wireless |
| Speed | Fastest | Faster | Fast |
| Reliability | Highly Reliable | Reliable | Less Reliable |
Network Architecture
Peer-to-Peer Network
All computers have equal responsibility and access. No dedicated server. Each computer acts as both client and server.
✓ Cheap and easy setup
✓ No dedicated server required
✓ Failure of one computer does not affect others
✗ Poor security
✗ Difficult backup and recovery
✗ Not suitable for large organizations
Client-Server Network
A central server controls all clients. Centralized control, high security. Server provides services to clients.
✓ Centralized administration
✓ Better security
✓ Easier backup and recovery, Suitable for large organizations
✗ Server failure affects entire network
✗ Expensive, Complex setup
Client-Server Architecture Diagram
Server
↔
Client 1
Client 2
Client N
All clients connected to a central server
Transmission Media
Guided / Wired Media
1. Twisted Pair Cable
Description: Pairs of wires twisted together to reduce EMI (Electromagnetic Interference).
Types: UTP (Unshielded Twisted Pair) – Cheap, commonly used | STP (Shielded Twisted Pair) – Shielded, expensive, better for long distance
Connectors: RJ45 (4 pair), RJ11 (2 pair)
Advantages: Cheap, flexible, good bandwidth
Disadvantages: Short distance only, affected by electromagnetic fields
Types: UTP (Unshielded Twisted Pair) – Cheap, commonly used | STP (Shielded Twisted Pair) – Shielded, expensive, better for long distance
Connectors: RJ45 (4 pair), RJ11 (2 pair)
Advantages: Cheap, flexible, good bandwidth
Disadvantages: Short distance only, affected by electromagnetic fields
2. Coaxial Cable
Description: Used in television broadcasting. High speed, large bandwidth, better reliability.
Connector: BNC Connector
Advantages: Faster than twisted pair, medium-range transmission
Disadvantages: Expensive, rarely used in modern networks
Connector: BNC Connector
Advantages: Faster than twisted pair, medium-range transmission
Disadvantages: Expensive, rarely used in modern networks
3. Fibre Optic Cable
Description: Made of glass or plastic and transmits data as light. Very high speed, immune to EMI, high security.
Connector: ST Connector
Advantages: High bandwidth, long-distance transmission, error-free communication
Disadvantages: Expensive, requires skilled manpower
Connector: ST Connector
Advantages: High bandwidth, long-distance transmission, error-free communication
Disadvantages: Expensive, requires skilled manpower
Unguided / Wireless Media
Microwave
Used for long-distance communication, requires Line of Sight (LOS)
Used for long-distance communication, requires Line of Sight (LOS)
Satellite
Microwave transmission system in space, uses uplink and downlink communication
Microwave transmission system in space, uses uplink and downlink communication
Radio Wave
Does not require Line of Sight, works on multiple frequencies
Does not require Line of Sight, works on multiple frequencies
Infrared
Uses invisible red light, used in TV remotes, cannot penetrate walls
Uses invisible red light, used in TV remotes, cannot penetrate walls
Satellite Communication
Earth Station (Uplink)
↑
🛰️
↓
Earth Station (Downlink)
Satellite communication uses uplink and downlink transmission
Transmission Media Comparison
| Media Type | Speed | Cost | Distance | Interference |
|---|---|---|---|---|
| Twisted Pair | Up to 1 Gbps | Cheap | Short (100m) | High |
| Coaxial | Up to 10 Mbps | Medium | Medium (500m) | Medium |
| Fiber Optic | Up to 100 Gbps | Expensive | Long (40+ km) | None |
| Microwave | Up to 100 Mbps | Medium | Long (LOS) | Weather affects |
| Satellite | Up to 100 Mbps | Very Expensive | Very Long | Weather affects |
Key Points Summary
LAN: Small area, fast, cheap, high security
MAN: City-wide, connects multiple LANs
WAN: Country/World-wide, Internet, slowest
Peer-to-Peer: No server, cheap, poor security
Client-Server: Central server, high security, expensive
Twisted Pair: Cheap, short distance (RJ45/RJ11)
Coaxial: Used in TV, BNC connector
Fiber Optic: Fastest, immune to EMI, expensive
Wireless: Microwave, Satellite, Radio, Infrared
Frequently Asked Questions (HSEB Pattern)
Differentiate between LAN, MAN, and WAN.
LAN covers small area (room/building), fastest, cheap. MAN covers city, connects LANs. WAN covers country/world, slowest, expensive (Internet).
Differentiate between Peer-to-Peer and Client-Server network.
Peer-to-Peer: No server, equal computers, cheap, poor security. Client-Server: Central server controls clients, high security, expensive.
Compare Twisted Pair, Coaxial, and Fiber Optic cable.
Twisted Pair: cheap, short, RJ45. Coaxial: medium, BNC. Fiber Optic: expensive, long, fast, immune to EMI.
What are the types of wireless media?
Microwave (LOS), Satellite (uplink/downlink), Radio Wave (no LOS), Infrared (short range, TV remotes).
Network Topology | NEB Class 12 Computer Science Notes
Based on Latest Syllabus 2080 | Complete Topology Concepts with Diagrams and Comparison
Updated according to latest syllabus of 2080 | Includes diagrams and detailed explanations
What is Network Topology?
Network topology is the physical arrangement of computers, devices, and cables in a network. It defines how different nodes are connected and how data flows between them.
Types of Network Topology
1. Bus Topology
─── ─── ───
↑ Backbone Cable ↑
↑ Backbone Cable ↑
All computers connect to a single backbone cable. Data travels in both directions along the cable.
Easy setup and installation
Cheap (requires less cable)
Suitable for small networks
Failure of backbone affects entire network
Performance decreases as computers increase
Difficult to troubleshoot
2. Ring Topology
──
│ ↺ │
──
│ ↺ │
──
Computers are connected in a circular form. Each computer has exactly two neighbors.
Equal access to all devices
Fast communication
Can cover greater distance
Failure of one computer/cable affects whole network
Difficult to add/remove computers
Slower than star topology
3. Star Topology
↘ ↙
(Hub)
↙ ↘
All devices connect to a central hub or switch. The hub acts as a central connection point.
Easy to add/remove computers
Failure of one computer does NOT affect others
Highly reliable and easy to troubleshoot
Most popular topology
Hub failure affects whole network
Requires more cable than bus
Expensive due to hub/switch
4. Mesh Topology
──
│ X │
──
│ X │
──
Devices are connected point-to-point. Every computer connects to every other computer.
Fast transmission (dedicated links)
Highly reliable – multiple paths
Easy fault identification
Maximum reliability
Very expensive
Complex structure and installation
Requires many cables (n(n-1)/2 links)
5. Tree (Hybrid) Topology
(Root Hub)
├── (Sub-Hub)
│ ├──
│ └──
└── (Sub-Hub)
├── (Sub-Hub)
│ ├──
│ └──
└── (Sub-Hub)
Combination of two or more topologies. Usually combines Star and Bus topology.
Flexible and scalable
Combines advantages of multiple topologies
Suitable for large organizations
Complex design and installation
Expensive
Difficult to manage
Topology Comparison
| Topology | Cost | Cable Length | Reliability | Popularity |
|---|---|---|---|---|
| Bus | Lowest | Short | Low | Low |
| Ring | Medium | Medium | Medium | Medium |
| Star | Medium | Long | High | Highest |
| Mesh | Highest | Longest | Highest | Low |
| Tree/Hybrid | High | Long | High | Low |
Star Topology – Most Popular Network Topology
Computer
→
Central Hub/Switch
←
Computer
All devices connected to a central hub – failure of one device doesn’t affect others
Important Terms
Protocol
Rules and conventions used for communication between devices in a network. Examples: TCP/IP, HTTP, FTP.
Rules and conventions used for communication between devices in a network. Examples: TCP/IP, HTTP, FTP.
Bandwidth
The maximum amount of data that can be transmitted over a network in a given time. Measured in bps, Mbps, Gbps.
The maximum amount of data that can be transmitted over a network in a given time. Measured in bps, Mbps, Gbps.
EMI (Electromagnetic Interference)
Disturbance caused by electromagnetic signals from external sources that affects network performance.
Disturbance caused by electromagnetic signals from external sources that affects network performance.
LOS (Line of Sight)
Direct visible path between a sender and receiver. Required for microwave and satellite communication.
Direct visible path between a sender and receiver. Required for microwave and satellite communication.
Quick Revision Summary
Communication = exchange of information
Networking = interconnected computers sharing resources
LAN = small area (room/building), MAN = city-wide, WAN = worldwide
Peer-to-Peer = no server, Client-Server = centralized server
Fibre optics = fastest transmission medium
Star topology = most popular topology (central hub)
Bus topology = uses backbone cable
Ring topology = forms a circle
Mesh topology = provides maximum reliability
Exam Tips
- Star topology is the most asked topology in exams – remember its advantages and diagram
- Bus topology is cheapest but least reliable – failure of backbone affects everything
- Mesh topology is most reliable but very expensive – useful for important connections
- Always draw diagrams when explaining topologies to get full marks
- Remember: Hub = failure point in Star, Backbone = failure point in Bus
Frequently Asked Questions (HSEB Pattern)
What is network topology? List its types.
Network topology is the physical arrangement of computers. Types: Bus, Ring, Star, Mesh, Tree/Hybrid.
Which is the most popular network topology and why?
Star topology is most popular because it is reliable, easy to add/remove computers, and failure of one computer doesn’t affect others.
Differentiate between Bus and Star topology.
Bus: single backbone cable, cheap, failure of cable affects all. Star: central hub, more expensive, failure of one computer doesn’t affect others.
What are the advantages of Mesh topology?
Fast transmission, highly reliable, multiple paths, easy fault identification, maximum reliability.
What is Hybrid topology?
Combination of two or more topologies. Example: Tree topology (combines Star and Bus).
OSI Model, Protocols, Transmission Impairments & Networking Devices
Based on Latest Syllabus 2080 | Complete Notes for NEB Class 12 Computer Science
OSI Reference Model | Protocols | Transmission Impairments | Networking Devices
OSI Reference Model
What is OSI Model?
The OSI (Open Systems Interconnection) model is a conceptual framework developed by the International Organization for Standardization (ISO) in 1984. It standardizes the functions of a communication system into 7 layers.
7 Layers of OSI Model
Layer 7 – Application Layer
Layer 6 – Presentation Layer
Layer 5 – Session Layer
Layer 4 – Transport Layer
Layer 3 – Network Layer
Layer 2 – Data Link Layer
Layer 1 – Physical Layer
Data flows from top to bottom (sender) and bottom to top (receiver)
Detailed OSI Layers
| Layer | Name | Function | PDU | Examples |
|---|---|---|---|---|
| 7 | Application | Provides network services to user applications | Data | HTTP, FTP, SMTP, DNS |
| 6 | Presentation | Data translation, encryption, compression | Data | SSL/TLS, JPEG, MPEG, ASCII |
| 5 | Session | Manages sessions, synchronization, checkpoints | Data | NetBIOS, RPC, PPTP |
| 4 | Transport | End-to-end connection, flow control, error control | Segment | TCP, UDP |
| 3 | Network | Routing, logical addressing (IP) | Packet | IP, ICMP, ARP, RIP |
| 2 | Data Link | Error detection, MAC addressing, framing | Frame | Ethernet, PPP, Switch |
| 1 | Physical | Transmits raw bits over physical medium | Bits | Hub, Repeater, Cable, RJ45 |
Easy Mnemonic to Remember OSI Layers
From Top to Bottom: All People Seem To Need Data Processing
(Application – Presentation – Session – Transport – Network – Data Link – Physical)
(Application – Presentation – Session – Transport – Network – Data Link – Physical)
Network Protocols
What is a Protocol?
A protocol is a set of rules and conventions that govern how data is transmitted and received over a network. It defines the format, timing, sequencing, and error control of data exchange.
Common Network Protocols
HTTP/HTTPS
Hypertext Transfer Protocol – Used for web browsing. HTTPS is secure version (port 80/443).
Hypertext Transfer Protocol – Used for web browsing. HTTPS is secure version (port 80/443).
SMTP
Simple Mail Transfer Protocol – Sending emails (port 25).
Simple Mail Transfer Protocol – Sending emails (port 25).
POP3/IMAP
Receiving emails. POP3 (port 110), IMAP (port 143).
Receiving emails. POP3 (port 110), IMAP (port 143).
FTP
File Transfer Protocol – Transferring files between computers (ports 20/21).
File Transfer Protocol – Transferring files between computers (ports 20/21).
Telnet/SSH
Remote login. Telnet (port 23 – insecure), SSH (port 22 – secure).
Remote login. Telnet (port 23 – insecure), SSH (port 22 – secure).
DNS
Domain Name System – Converts domain names to IP addresses (port 53).
Domain Name System – Converts domain names to IP addresses (port 53).
DHCP
Dynamic Host Configuration Protocol – Automatically assigns IP addresses.
Dynamic Host Configuration Protocol – Automatically assigns IP addresses.
TCP
Transmission Control Protocol – Connection-oriented, reliable, ensures delivery.
Transmission Control Protocol – Connection-oriented, reliable, ensures delivery.
UDP
User Datagram Protocol – Connectionless, faster but less reliable.
User Datagram Protocol – Connectionless, faster but less reliable.
IP
Internet Protocol – Handles addressing and routing of packets.
Internet Protocol – Handles addressing and routing of packets.
TCP/IP Model
| TCP/IP Layer | OSI Equivalent | Protocols |
|---|---|---|
| Application | Application, Presentation, Session | HTTP, FTP, SMTP, DNS, Telnet |
| Transport | Transport | TCP, UDP |
| Internet | Network | IP, ICMP, ARP |
| Network Access | Data Link, Physical | Ethernet, Wi-Fi, PPP |
Transmission Impairments
What are Transmission Impairments?
Transmission impairments are undesirable effects that occur when a signal travels through a transmission medium, causing distortion or loss of data. These impairments degrade the quality of communication.
Attenuation
Loss of signal strength as it travels through a medium. Signals weaken over distance.
Solution: Amplifiers/Repeaters
Loss of signal strength as it travels through a medium. Signals weaken over distance.
Solution: Amplifiers/Repeaters
Distortion
Change in the shape of the signal due to different propagation speeds of different frequency components.
Solution: Equalization
Change in the shape of the signal due to different propagation speeds of different frequency components.
Solution: Equalization
Noise
Unwanted electrical or electromagnetic signals that interfere with the original signal.
Types: Thermal Noise, Intermodulation Noise, Crosstalk, Impulse Noise
Unwanted electrical or electromagnetic signals that interfere with the original signal.
Types: Thermal Noise, Intermodulation Noise, Crosstalk, Impulse Noise
Delay Distortion
Different frequency components travel at different speeds, causing phase shift.
Common in guided media (Twisted Pair, Coaxial)
Different frequency components travel at different speeds, causing phase shift.
Common in guided media (Twisted Pair, Coaxial)
Important Terms
Bandwidth
Maximum data transfer rate of a network. Measured in bps, Mbps, Gbps.
Maximum data transfer rate of a network. Measured in bps, Mbps, Gbps.
Latency
Time delay between sending and receiving data. Also called delay.
Time delay between sending and receiving data. Also called delay.
Throughput
Actual data transfer rate achieved (not theoretical maximum).
Actual data transfer rate achieved (not theoretical maximum).
Jitter
Variation in packet arrival time. Critical for real-time applications (VoIP, video).
Variation in packet arrival time. Critical for real-time applications (VoIP, video).
Signal-to-Noise Ratio (SNR)
Ratio of signal power to noise power. Higher SNR = better quality.
Ratio of signal power to noise power. Higher SNR = better quality.
Electromagnetic Interference (EMI)
Disturbance from external electromagnetic fields affecting signals.
Disturbance from external electromagnetic fields affecting signals.
Different Networking Devices
NIC (Network Interface Card)
Connects computer to network. Has unique MAC address. Works at Physical Layer.
Connects computer to network. Has unique MAC address. Works at Physical Layer.
Hub
Broadcasts data to all ports. Works at Physical Layer. Simple but inefficient.
Broadcasts data to all ports. Works at Physical Layer. Simple but inefficient.
Switch
Forwards data to specific port based on MAC address. Works at Data Link Layer. More efficient than hub.
Forwards data to specific port based on MAC address. Works at Data Link Layer. More efficient than hub.
Router
Connects different networks. Forwards packets based on IP address. Works at Network Layer.
Connects different networks. Forwards packets based on IP address. Works at Network Layer.
Bridge
Connects two similar network segments. Filters traffic based on MAC address. Data Link Layer.
Connects two similar network segments. Filters traffic based on MAC address. Data Link Layer.
Repeater
Regenerates signal to extend distance. Works at Physical Layer.
Regenerates signal to extend distance. Works at Physical Layer.
Gateway
Connects networks with different protocols. Translates between formats. Works at Application Layer.
Connects networks with different protocols. Translates between formats. Works at Application Layer.
Modem
Modulates/Demodulates signals for internet access. Converts digital to analog and vice versa.
Modulates/Demodulates signals for internet access. Converts digital to analog and vice versa.
Access Point (AP)
Allows wireless devices to connect to wired network.
Allows wireless devices to connect to wired network.
Firewall
Security device that filters incoming/outgoing traffic based on rules.
Security device that filters incoming/outgoing traffic based on rules.
Networking Device Comparison
| Device | Layer | Function | Intelligence |
|---|---|---|---|
| Hub | Physical | Broadcasts data to all ports | No (Dumb) |
| Switch | Data Link | Forwards to specific MAC address | Yes |
| Router | Network | Routes packets between networks | Highly Intelligent |
| Bridge | Data Link | Connects two network segments | Partial |
| Repeater | Physical | Regenerates signals | No |
| Gateway | Application | Connects different protocol networks | Highly Intelligent |
Network Devices Connection Diagram
PC
→
Switch
→
Router
→
Internet
Typical home/office network: PC → Switch → Router → Internet
Quick Revision Summary
- OSI Layers (7): Application, Presentation, Session, Transport, Network, Data Link, Physical
- TCP/UDP: TCP = reliable connection-oriented, UDP = fast connectionless
- HTTP/HTTPS: Web browsing (port 80/443), FTP: File transfer (port 20/21), SMTP: Email sending (port 25)
- Transmission Impairments: Attenuation (signal loss), Distortion (shape change), Noise (interference)
- Hub vs Switch: Hub broadcasts (dumb), Switch forwards to specific port (smart)
- Router: Connects networks, uses IP addresses
- Gateway: Connects different protocol networks
Frequently Asked Questions (HSEB Pattern)
What is OSI Model? Explain its layers.
OSI model has 7 layers: Application, Presentation, Session, Transport, Network, Data Link, Physical. Each layer performs specific functions for network communication.
Differentiate between TCP and UDP.
TCP: Connection-oriented, reliable, slower, ensures delivery. UDP: Connectionless, unreliable, faster, no guarantee of delivery.
What are transmission impairments? List them.
Transmission impairments degrade signal quality. Types: Attenuation (signal loss), Distortion (shape change), Noise (unwanted signals).
Differentiate between Hub and Switch.
Hub: Physical layer, broadcasts to all ports, dumb device. Switch: Data Link layer, forwards to specific MAC address, intelligent.
What is the function of a Router?
Router connects different networks, forwards packets based on IP addresses, works at Network Layer. Used to connect LAN to internet.