Question 1(a) [3 marks]

Explain star topology in detail.

Answer: Star topology connects all devices to a central hub or switch. Each device has dedicated point-to-point connection with central device.

Diagram:

    Computer A
        |
        |
Computer D ---- HUB ---- Computer B
        |
        |
    Computer C

Key Features:

Central Hub: All connections pass through central device
Dedicated Links: Each node has separate connection
Easy Management: Simple to add/remove devices

Mnemonic: "Star Shines Central" - All devices connect to central point

Question 1(b) [4 marks]

Explain client-server network.

Answer: Client-server is network architecture where clients request services from centralized servers. Server provides resources and services to multiple clients.

Table: Client vs Server

Client	Server
Requests services	Provides services
Limited resources	Powerful hardware
Depends on server	Independent operation

Key Components:

Client: Requests data/services from server
Server: Provides centralized resources and processing
Network: Medium for communication between client-server

Mnemonic: "Client Calls, Server Serves"

Question 1(c) [7 marks]

Write a functional description of all layer of TCP/IP model.

Answer: TCP/IP model has four layers providing end-to-end communication over networks.

Table: TCP/IP Model Layers

Layer	Function	Protocols
Application	User interface, network services	HTTP, FTP, SMTP
Transport	End-to-end delivery, error control	TCP, UDP
Internet	Routing, logical addressing	IP, ICMP, ARP
Network Access	Physical transmission	Ethernet, WiFi

Layer Functions:

Application Layer: Provides network services to user applications
Transport Layer: Ensures reliable data delivery between processes
Internet Layer: Routes packets across multiple networks using IP
Network Access Layer: Handles physical transmission of data

Mnemonic: "All Transport Internet Networks" (ATIN)

Question 1(c OR) [7 marks]

Explain the functions of Data Link Layer & Network Layer of OSI reference model.

Answer: Data Link and Network layers provide reliable transmission and routing capabilities in OSI model.

Table: Layer Comparison

Feature	Data Link Layer	Network Layer
Main Function	Node-to-node delivery	End-to-end delivery
Addressing	MAC addresses	IP addresses
Error Control	Frame-level	Packet-level

Data Link Layer Functions:

Framing: Organizes bits into frames
Error Control: Detects and corrects transmission errors
Flow Control: Manages data transmission rate

Network Layer Functions:

Routing: Determines best path for packets
Logical Addressing: Uses IP addresses for identification
Packet Forwarding: Routes packets between networks

Mnemonic: "Data Links Locally, Network Routes Globally"

Question 2(a) [3 marks]

Compare repeater and hub.

Answer: Both devices amplify signals but operate differently in network architecture.

Table: Repeater vs Hub

Feature	Repeater	Hub
Ports	2 ports	Multiple ports
Function	Signal amplification	Signal distribution
Collision Domain	Single	Single shared

Key Differences:

Port Count: Repeater has 2 ports, hub has multiple
Usage: Repeater extends distance, hub connects multiple devices

Mnemonic: "Repeater Extends, Hub Connects"

Question 2(b) [4 marks]

Explain wireless LAN.

Answer: Wireless LAN uses radio waves for network communication without physical cables.

Diagram:

  Laptop     Desktop
    |   \   /   |
    |    \ /    |
    |   Access  |
    |   Point   |
    |     |     |
    Mobile   Printer

Key Components:

Access Point: Central wireless communication device
Wireless Clients: Devices with WiFi capability
Radio Frequencies: 2.4GHz and 5GHz bands commonly used

Advantages:

Mobility: Users can move freely within coverage area
Easy Installation: No physical cable installation required

Mnemonic: "Wireless Waves Connect"

Question 2(c) [7 marks]

Explain FDDI & CDDI.

Answer: FDDI and CDDI are ring-based network technologies providing high-speed data transmission.

Table: FDDI vs CDDI Comparison

Feature	FDDI	CDDI
Medium	Fiber optic	Copper (UTP)
Speed	100 Mbps	100 Mbps
Distance	200 km	100 meters
Cost	High	Lower

FDDI Features:

Dual Ring: Primary and secondary rings for fault tolerance
Token Passing: Deterministic access method
Self-Healing: Automatic recovery from failures

CDDI Features:

Copper Medium: Uses unshielded twisted pair cables
Same Protocol: Identical to FDDI except transmission medium
Cost Effective: Lower implementation cost than FDDI

Ring Structure:

    Station A
        |
Station D --+-- Station B
        |
    Station C

Mnemonic: "FDDI Fiber Fast, CDDI Copper Cheap"

Question 2(a OR) [3 marks]

How does a firewall protect data.

Answer: Firewall acts as security barrier between trusted internal network and untrusted external networks.

Protection Methods:

Packet Filtering: Examines packet headers for security rules
Access Control: Blocks unauthorized access attempts
Traffic Monitoring: Monitors all incoming and outgoing traffic

Mnemonic: "Firewall Filters Foes"

Question 2(b OR) [4 marks]

Explain the structure of FDDI and give its advantages.

Answer: FDDI uses dual counter-rotating rings for high-speed, fault-tolerant networking.

Structure Components:

Primary Ring: Main data transmission path
Secondary Ring: Backup path for fault recovery
Dual Attachment Stations: Connect to both rings
Single Attachment Stations: Connect to one ring only

Advantages:

High Speed: 100 Mbps transmission rate
Fault Tolerance: Automatic recovery using secondary ring
Long Distance: Supports up to 200 km networks

Mnemonic: "FDDI Dual Rings Deliver Reliability"

Question 2(c OR) [7 marks]

Explain and distinguish Ethernet, Fast Ethernet, Gigabit Ethernet.

Answer: Evolution of Ethernet standards providing increasing bandwidth and improved performance.

Table: Ethernet Comparison

Feature	Ethernet	Fast Ethernet	Gigabit Ethernet
Speed	10 Mbps	100 Mbps	1000 Mbps
Standard	802.3	802.3u	802.3z/ab
Cable	Coax/UTP	UTP/Fiber	UTP/Fiber
Distance	500m (coax)	100m (UTP)	100m (UTP)

Key Differences:

Bandwidth: Each generation increases speed by factor of 10
Media Support: Newer standards support more cable types
Backward Compatibility: Higher standards support lower speeds

Applications:

Ethernet: Legacy systems, basic connectivity
Fast Ethernet: Desktop connections, small networks
Gigabit Ethernet: Server connections, backbone networks

Mnemonic: "Ethernet Evolves: 10-100-1000"

Question 3(a) [3 marks]

Explain types of DSL.

Answer: DSL provides high-speed internet over existing telephone lines using different frequency bands.

Table: DSL Types

Type	Full Form	Speed
ADSL	Asymmetric DSL	Up to 8 Mbps down
SDSL	Symmetric DSL	Equal up/down
VDSL	Very-high-bit-rate DSL	Up to 52 Mbps

Characteristics:

ADSL: Different upload/download speeds for home users
SDSL: Same speed both directions for business use

Mnemonic: "DSL: Asymmetric, Symmetric, Very-fast"

Question 3(b) [4 marks]

Explain ARP & RARP.

Answer: ARP and RARP provide address resolution between IP and MAC addresses.

Table: ARP vs RARP

Feature	ARP	RARP
Purpose	IP to MAC	MAC to IP
Used by	All devices	Diskless workstations
Direction	Logical to Physical	Physical to Logical

ARP Process:

Request: Broadcast "Who has IP address X?"
Reply: Target responds with MAC address
Caching: Stores mapping in ARP table

RARP Process:

Request: "What is my IP address?"
Server Response: RARP server provides IP address

Mnemonic: "ARP: Address Resolution Protocol, RARP: Reverse ARP"

Question 3(c) [7 marks]

Describe circuit switching and packet switching.

Answer: Two fundamental approaches for establishing communication paths in networks.

Table: Circuit vs Packet Switching

Feature	Circuit Switching	Packet Switching
Path Setup	Dedicated path	No dedicated path
Resource Usage	Reserved throughout	Shared dynamically
Delay	Constant	Variable
Examples	Telephone	Internet

Circuit Switching:

Path Establishment: Dedicated circuit created before communication
Resource Reservation: Bandwidth reserved for entire session
Guaranteed Service: Consistent performance throughout connection

Packet Switching:

Store and Forward: Packets stored temporarily at intermediate nodes
Dynamic Routing: Each packet can take different path
Resource Sharing: Network resources shared among multiple connections

Diagram: Packet Switching

Source --- Router1 --- Router2 --- Destination
    \         |         /
     \        |        /
      \--- Router3 ---/

Mnemonic: "Circuit Commits, Packet Partitions"

Question 3(a OR) [3 marks]

Describe DHCP & BOOTP protocol.

Answer: Both protocols automatically assign IP addresses to network devices.

Table: DHCP vs BOOTP

Feature	DHCP	BOOTP
Address Type	Dynamic/Static	Static only
Lease Time	Temporary	Permanent
Configuration	Automatic	Manual setup

Functions:

DHCP: Dynamic address assignment with lease management
BOOTP: Bootstrap protocol for diskless workstations

Mnemonic: "DHCP Dynamic, BOOTP Bootstrap"

Question 3(b OR) [4 marks]

Explain IPv4 & IPv6 in detail.

Answer: Internet Protocol versions providing addressing and routing capabilities.

Table: IPv4 vs IPv6

Feature	IPv4	IPv6
Address Size	32 bits	128 bits
Address Format	Dotted decimal	Hexadecimal
Address Space	4.3 billion	340 undecillion
Header Size	20-60 bytes	40 bytes

IPv4 Features:

Address Format: 192.168.1.1 (4 octets)
Classes: A, B, C, D, E address classes
NAT Required: Address shortage requires NAT

IPv6 Features:

Address Format: 2001:db8::1 (8 groups of 4 hex digits)
No NAT Needed: Abundant address space
Built-in Security: IPSec support mandatory

Mnemonic: "IPv4 Four Octets, IPv6 Six-teen Bytes"

Question 3(c OR) [7 marks]

Draw and explain constructional details of twisted pair cable, coaxial cable, and fiber optic cable with label.

Answer: Three main types of guided transmission media with different construction and characteristics.

Twisted Pair Cable:

  Outer Jacket
       |
   +---+---+
   |  / \  |  Twisted Pairs
   | /   \ |  (4 pairs)
   +-------+
       |
   Insulation

Coaxial Cable:

   Outer Jacket
        |
    +---+---+
    |   |   |  Outer Conductor (Shield)
    | +-+-+ |  Dielectric Insulator
    | | | | |  Inner Conductor (Copper)
    +-+-+-+-+

Fiber Optic Cable:

   Outer Jacket
        |
    +---+---+
    |   |   |  Cladding
    | +-+-+ |  Core (Glass/Plastic)
    |   |   |  Light travels here
    +---+---+

Construction Details:

Twisted Pair: Copper wires twisted to reduce interference
Coaxial: Central conductor surrounded by dielectric and shield
Fiber Optic: Glass core with cladding for total internal reflection

Characteristics:

Twisted Pair: Low cost, easy installation, limited bandwidth
Coaxial: Better shielding, higher bandwidth than twisted pair
Fiber Optic: Highest bandwidth, immune to electromagnetic interference

Mnemonic: "Twisted Copper, Coax Shielded, Fiber Light"

Question 4(a) [3 marks]

Name any three data link layer protocol and explain any one in detail.

Answer: Common data link layer protocols: HDLC, PPP, Ethernet.

HDLC (High-Level Data Link Control):

Frame Structure: Flag, Address, Control, Data, FCS, Flag
Error Control: Uses sequence numbers and acknowledgments
Flow Control: Sliding window protocol for efficient transmission

Key Features:

Bit-oriented: Works with bit streams rather than characters
Full-duplex: Simultaneous bidirectional communication

Mnemonic: "HDLC Handles Data Link Control"

Question 4(b) [4 marks]

Explain TCP and UDP protocol.

Answer: Transport layer protocols providing different levels of service reliability.

Table: TCP vs UDP

Feature	TCP	UDP
Connection	Connection-oriented	Connectionless
Reliability	Reliable	Unreliable
Speed	Slower	Faster
Header Size	20+ bytes	8 bytes

TCP Features:

Connection Setup: Three-way handshake establishes connection
Error Recovery: Retransmits lost packets automatically
Flow Control: Prevents sender from overwhelming receiver

UDP Features:

No Connection: Sends data without establishing connection
Best Effort: No guarantee of delivery or order
Low Overhead: Minimal header for fast transmission

Mnemonic: "TCP Trustworthy, UDP Unreliable but Quick"

Question 4(c) [7 marks]

Describe VoIP with example.

Answer: Voice over Internet Protocol transmits voice communications over IP networks instead of traditional telephone systems.

VoIP Components:

IP Phone: Hardware device for VoIP calls
Softphone: Software application for computer-based calls
Gateway: Connects VoIP to traditional phone networks
PBX: Private branch exchange for business phone systems

VoIP Process:

Voice Capture: Microphone converts voice to analog signal
Digitization: ADC converts analog to digital samples
Compression: Codec compresses audio data
Packetization: Voice data divided into IP packets
Transmission: Packets sent over IP network
Reconstruction: Receiving end reassembles and plays audio

Example Applications:

Skype: Consumer VoIP service for personal calls
WhatsApp Calling: Mobile VoIP application
Business PBX: Corporate phone systems using VoIP

Advantages:

Cost Effective: Lower long-distance call costs
Feature Rich: Video calling, conferencing, call forwarding
Scalability: Easy to add new users

Disadvantages:

Internet Dependency: Requires stable internet connection
Quality Issues: May suffer from network congestion
Power Dependency: Requires electricity unlike traditional phones

Mnemonic: "VoIP: Voice over Internet Protocol"

Question 4(a OR) [3 marks]

Explain DNS (Domain Name System).

Answer: DNS translates human-readable domain names into IP addresses for network communication.

DNS Components:

Domain Names: Hierarchical naming system (www.example.com)
Name Servers: Computers that store DNS records
Resolvers: Client software that queries DNS servers

DNS Process:

User enters domain name in browser
Local resolver queries DNS server
DNS server returns corresponding IP address

Mnemonic: "DNS: Domain Name to IP Address"

Question 4(b OR) [4 marks]

Write a short note on DSL.

Answer: Digital Subscriber Line provides high-speed internet access over existing telephone infrastructure.

DSL Technology:

Frequency Division: Uses higher frequencies than voice calls
Simultaneous Use: Internet and phone can work together
Distance Limitation: Performance decreases with distance from exchange

DSL Types:

ADSL: Asymmetric speeds for residential users
SDSL: Symmetric speeds for business applications
VDSL: Very high speeds over short distances

Advantages:

Existing Infrastructure: Uses existing telephone lines
Always On: Continuous internet connection
Cost Effective: Lower cost than dedicated lines

Mnemonic: "DSL: Digital Subscriber Line over Phone Lines"

Question 4(c OR) [7 marks]

Explain forum and blogs with example.

Answer: Online platforms for information sharing and community interaction.

Table: Forum vs Blog

Feature	Forum	Blog
Structure	Discussion threads	Chronological posts
Interaction	Multi-user discussions	Comments on posts
Moderation	Community moderated	Author controlled
Purpose	Community support	Information sharing

Forum Characteristics:

Discussion Threads: Topics organized by subject
User Participation: Multiple users contribute to discussions
Categories: Topics organized into different sections
Moderation: Community rules and moderators maintain order

Blog Characteristics:

Personal Publishing: Individual or organization publishes content
Chronological Order: Posts displayed by date
Comments: Readers can respond to blog posts
RSS Feeds: Readers can subscribe to updates

Examples:

Technical Forums: Stack Overflow for programming questions
Community Forums: Reddit for diverse topics
Personal Blogs: Individual websites sharing experiences
Corporate Blogs: Company blogs for marketing and updates

Benefits:

Knowledge Sharing: Users share expertise and experiences
Community Building: Brings together people with common interests
Problem Solving: Forums help users find solutions
Content Creation: Blogs provide platform for publishing

Mnemonic: "Forums Foster Discussion, Blogs Broadcast Information"

Question 5(a) [3 marks]

Define the terms "encryption".

Answer: Encryption converts plaintext data into ciphertext to protect information from unauthorized access.

Encryption Process:

Plaintext: Original readable data
Algorithm: Mathematical process for transformation
Key: Secret parameter used in encryption algorithm
Ciphertext: Encrypted unreadable data

Purpose:

Confidentiality: Prevents unauthorized data access
Data Protection: Secures sensitive information during transmission

Mnemonic: "Encryption: Plain to Cipher with Key"

Question 5(b) [4 marks]

Explain any two of following: (1) WWW (2) FTP (3) SMTP

Answer:

WWW (World Wide Web):

Hypertext System: Documents linked through hyperlinks
HTTP Protocol: HyperText Transfer Protocol for web communication
Web Browser: Client software for accessing web pages
Web Server: Hosts websites and serves web pages

FTP (File Transfer Protocol):

File Transfer: Protocol for transferring files between computers
Client-Server: FTP client connects to FTP server
Two Modes: Active and passive modes for data transfer
Authentication: Username and password for access control

Features:

WWW: Graphical interface, multimedia support, hyperlinks
FTP: Large file transfer, directory navigation, resume capability

Mnemonic: "WWW: Web World Wide, FTP: File Transfer Protocol"

Question 5(c) [7 marks]

Difference between symmetric and asymmetric encryption algorithms

Answer: Two fundamental approaches to cryptographic key management with different characteristics.

Table: Symmetric vs Asymmetric Encryption

Feature	Symmetric	Asymmetric
Keys	Single shared key	Key pair (public/private)
Speed	Fast	Slower
Key Distribution	Difficult	Easier
Key Management	Complex for large groups	Simpler
Examples	AES, DES	RSA, ECC

Symmetric Encryption:

Single Key: Same key used for encryption and decryption
Speed: Fast processing due to simple algorithms
Key Sharing Problem: Secure key distribution challenge
Session Keys: Often used for bulk data encryption

Asymmetric Encryption:

Key Pair: Public key for encryption, private key for decryption
Digital Signatures: Private key signs, public key verifies
Key Exchange: Solves key distribution problem
Computationally Intensive: Slower than symmetric encryption

Usage Scenarios:

Symmetric: Bulk data encryption, secure communications
Asymmetric: Key exchange, digital signatures, authentication

Hybrid Approach:

Best of Both: Asymmetric for key exchange, symmetric for data
SSL/TLS: Uses both types for secure web communications

Security Considerations:

Symmetric: Key compromise affects all communications
Asymmetric: Private key compromise affects only one party

Mnemonic: "Symmetric Single Key, Asymmetric Key Pair"

Question 5(a OR) [3 marks]

Write brief note on Cyber Security.

Answer: Cyber security protects digital systems, networks, and data from digital attacks and unauthorized access.

Key Components:

Network Security: Protects network infrastructure from intrusions
Data Protection: Safeguards sensitive information from theft
Application Security: Secures software applications from vulnerabilities

Common Threats:

Malware: Viruses, worms, trojans that damage systems
Phishing: Fraudulent attempts to steal credentials

Mnemonic: "Cyber Security: Protect Digital Assets"

Question 5(b OR) [4 marks]

Explain hacking and its precautions.

Answer: Hacking involves unauthorized access to computer systems, often with malicious intent.

Types of Hacking:

White Hat: Ethical hacking for security testing
Black Hat: Malicious hacking for illegal purposes
Gray Hat: Between ethical and malicious hacking

Common Hacking Methods:

Password Attacks: Brute force, dictionary attacks
Social Engineering: Manipulating people to reveal information
Malware: Viruses, trojans, ransomware
Network Attacks: Man-in-the-middle, packet sniffing

Precautions:

Strong Passwords: Complex, unique passwords for all accounts
Regular Updates: Keep software and systems updated
Firewall: Use firewall to block unauthorized access
Antivirus: Install and update antivirus software regularly

Mnemonic: "Hacking Hurts, Precautions Protect"

Question 5(c OR) [7 marks]

Briefly describe the Information Technology (Amendment) Act, 2008, and its impact on cyber laws in India.

Answer: The IT Amendment Act 2008 significantly strengthened India's cyber law framework and expanded the scope of cybercrime legislation.

Key Amendments:

Data Protection: Enhanced provisions for protecting sensitive personal data
Cybercrime Definitions: Expanded definitions of cybercrime including identity theft
Penalties: Increased penalties for various cyber offenses
Cyber Terrorism: Introduced provisions to deal with cyber terrorism

Major Provisions:

Section 43A: Data protection and compensation for negligence
Section 66A: Punishment for offensive messages (later struck down)
Section 66C: Identity theft punishment
Section 66D: Cheating by personation using computer resource

Impact on Cyber Laws:

Legal Framework: Provided comprehensive legal framework for cybercrime
Business Compliance: Mandated data protection measures for businesses
Law Enforcement: Empowered authorities with investigation tools
International Cooperation: Facilitated cooperation in cybercrime investigation

Regulatory Bodies:

CERT-In: Computer Emergency Response Team for incident response
Cyber Cells: Specialized police units for cybercrime investigation
Adjudicating Officers: For compensation and penalty determination

Data Protection Requirements:

Reasonable Security: Companies must implement reasonable security practices
Breach Notification: Mandatory reporting of data breaches
Compensation: Victims can claim compensation for data breaches

Challenges and Criticisms:

Implementation: Difficulty in implementation across diverse digital landscape
Jurisdiction: Cross-border cybercrime investigation challenges
Technology Gap: Keeping pace with rapidly evolving technology

Recent Developments:

Digital India: Integration with Digital India initiatives
Privacy Laws: Preparation for comprehensive data protection legislation
Emerging Technologies: Addressing challenges from AI, IoT, blockchain

Mnemonic: "IT Act 2008: India's Cyber Law Foundation"