Computer Networks & Data Communication (4361101) - Summer 2025 Solution

Question 1(a) [3 marks]

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State different DSL technology and discuss ADSL

Answer:

DSL Technology Types:

ADSL Features:

• Asymmetric: Different upload/download speeds
• Frequency Division: Uses existing copper telephone lines
• Download Speed: Higher than upload speed

Mnemonic: “ADSL Downloads Faster”

Question 1(b) [4 marks]

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Describe the network classification of based on Architecture.

Answer:

Network Architecture Classification:

Client-Server Advantages:

• Centralized Control: Easy management and security
• Resource Sharing: Efficient utilization of resources
• Scalability: Can handle more users effectively
• Data Security: Better backup and recovery

P2P Characteristics:

• Decentralized: No single point of failure
• Cost Effective: No need for dedicated server

Mnemonic: “Client Serves Better”

Question 1(c) [7 marks]

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Draw the diagram of OSI Model and explain in detail with all layers.

Answer:

graph TD
    A[Application Layer - 7] --> B[Presentation Layer - 6]
    B --> C[Session Layer - 5]
    C --> D[Transport Layer - 4]
    D --> E[Network Layer - 3]
    E --> F[Data Link Layer - 2]
    F --> G[Physical Layer - 1]

OSI Layer Functions:

Key Features:

• Layered Approach: Each layer serves specific function
• Standardization: Universal communication model
• Troubleshooting: Easy to identify network problems

Mnemonic: “All People Seem To Need Data Processing”

Question 1(c OR) [7 marks]

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Draw the diagram of TCP/IP protocol suite and explain the functions of Application Layer, Transport Layer and Network Layer in detail.

Answer:

graph TD
    A[Application Layer] --> B[Transport Layer]
    B --> C[Network Layer]
    C --> D[Data Link Layer]

    A1[HTTP, FTP, SMTP, DNS] --> A
    B1[TCP, UDP] --> B
    C1[IP, ICMP, ARP] --> C

Layer Functions:

Application Layer Functions:

• Web Services: HTTP for web browsing
• File Transfer: FTP for file sharing
• Email: SMTP for mail delivery

Transport Layer Functions:

• Reliable Delivery: TCP ensures data integrity
• Unreliable Delivery: UDP for fast transmission
• Port Numbers: Identify specific applications

Network Layer Functions:

• Logical Addressing: IP addresses for devices
• Routing: Best path selection for packets
• Fragmentation: Breaking large packets

Mnemonic: “Applications Transport Networks”

Question 2(a) [3 marks]

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Explain WWW.

Answer:

World Wide Web (WWW):

WWW Features:

• Hypertext: Linked documents using HTML
• Client-Server Model: Browser requests, server responds
• Universal Access: Platform independent

Components:

• HTML: Markup language for web pages
• Browser: Firefox, Chrome, Safari

Mnemonic: “Web Works Worldwide”

Question 2(b) [4 marks]

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Explain FDDI and CDDI.

Answer:

FDDI vs CDDI Comparison:

FDDI Features:

• Dual Ring Topology: Primary and secondary rings
• Token Passing: Access control method
• Fault Tolerance: Self-healing capability

CDDI Features:

• Copper Based: Uses twisted pair cables
• Cost Effective: Cheaper than fiber
• Limited Distance: Shorter transmission range

Applications:

• FDDI: Backbone networks, long distances
• CDDI: Local area networks, cost-sensitive environments

Mnemonic: “Fiber Fast, Copper Cheap”

Question 2(c) [7 marks]

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Describe a network management system with functions of OS, CLI, Administrative Functions, Interfaces.

Answer:

graph TD
    A[Network Management System] --> B[Operating System]
    A --> C[CLI Interface]
    A --> D[Administrative Functions]
    A --> E[GUI Interfaces]

    B --> B1[Resource Management]
    C --> C1[Command Line]
    D --> D1[User Management]
    E --> E1[Graphical Interface]

Network Management Components:

Operating System Functions:

• Process Management: Control running applications
• Memory Management: Allocate system resources
• File System: Organize and store data

CLI Functions:

• Direct Commands: Text-based control
• Scripting: Automated task execution
• Remote Access: SSH, Telnet connections

Administrative Functions:

• User Management: Create, modify user accounts
• Security Policies: Access control, permissions
• System Monitoring: Performance tracking

Interfaces:

• GUI: Graphical user interface for easy navigation
• Web Interface: Browser-based management
• SNMP: Simple Network Management Protocol

Mnemonic: “Operating CLI Administers Interfaces”

Question 2(a OR) [3 marks]

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Compare connection-oriented protocol and connection less protocol.

Answer:

Protocol Comparison:

Connection-Oriented Features:

• Three-way Handshake: Establishes connection before data transfer
• Reliable Delivery: Guarantees packet delivery and order

Connectionless Features:

• No Setup: Direct data transmission
• Best Effort: No delivery guarantee

Mnemonic: “TCP Connects, UDP Delivers”

Question 2(b OR) [4 marks]

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Explain Network device Repeater.

Answer:

Repeater Functions:

Repeater Characteristics:

• Physical Layer Device: Operates at Layer 1
• Bit-by-Bit: Regenerates digital signals
• No Intelligence: Cannot filter or route data

Applications:

• LAN Extension: Extend Ethernet segments
• Signal Recovery: Restore degraded signals

Limitations:

• Collision Domain: Does not segment collisions
• No Filtering: Forwards all signals

Mnemonic: “Repeater Regenerates Signals”

Question 2(c OR) [7 marks]

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Differentiate between Router, Hub and Switch.

Answer:

Network Device Comparison:

graph TD
    A[Network Devices] --> B[Hub - Layer 1]
    A --> C[Switch - Layer 2]
    A --> D[Router - Layer 3]

    B --> B1[Shared Bandwidth]
    C --> C1[Dedicated Bandwidth]
    D --> D1[Inter-network Connection]

Hub Characteristics:

• Shared Medium: All ports share bandwidth
• Half Duplex: Cannot send and receive simultaneously
• Collision Prone: Single collision domain

Switch Characteristics:

• MAC Address Table: Learns device locations
• Full Duplex: Simultaneous send/receive
• VLAN Support: Virtual network segmentation

Router Characteristics:

• IP Routing: Forwards packets between networks
• Routing Table: Maintains network topology
• NAT Support: Network Address Translation

Applications:

• Hub: Legacy networks (mostly obsolete)
• Switch: LAN connectivity, VLAN implementation
• Router: Internet connectivity, WAN connections

Mnemonic: “Hub Shares, Switch Switches, Router Routes”

Question 3(a) [3 marks]

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Draw neat diagram of UTP, Coaxial and Fiber optic cable

Answer:

Cable Characteristics:

Mnemonic: “Twisted Copper Glass”

Question 3(b) [4 marks]

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Differentiate switching circuit and packet switching circuit.

Answer:

Switching Methods Comparison:

Circuit Switching Features:

• Dedicated Path: Exclusive connection between communicating parties
• Constant Bandwidth: Fixed data rate throughout communication
• Setup Phase: Connection established before data transfer

Packet Switching Features:

• Store and Forward: Packets stored at intermediate nodes
• Dynamic Routing: Different paths for different packets
• Resource Sharing: Multiple users share network resources

Advantages:

• Circuit: Guaranteed bandwidth, low latency
• Packet: Efficient resource utilization, fault tolerance

Mnemonic: “Circuit Connects, Packet Shares”

Question 3(c) [7 marks]

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Describe unguided media and guided media.

Answer:

Transmission Media Classification:

graph TD
    A[Transmission Media] --> B[Guided Media]
    A --> C[Unguided Media]

    B --> B1[Twisted Pair]
    B --> B2[Coaxial Cable]
    B --> B3[Fiber Optic]
    
    C --> C1[Radio Waves]
    C --> C2[Microwaves]
    C --> C3[Infrared]

Guided Media Characteristics:

Unguided Media Characteristics:

Guided Media Advantages:

• Security: Physical protection from interference
• Reliability: Stable signal transmission
• High Bandwidth: Greater data capacity

Unguided Media Advantages:

• Mobility: Wireless connectivity
• Coverage: Wide area reach
• Installation: No physical cabling required

Applications:

• Guided: LAN, backbone networks, high-speed connections
• Unguided: Mobile networks, satellite communication, WiFi

Mnemonic: “Guided Wires, Unguided Airs”

Question 3(a OR) [3 marks]

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Discuss various connectors used in Computer Networks.

Answer:

Network Connectors:

Connector Features:

• RJ-45: 8-pin modular connector for twisted pair
• BNC: Bayonet connector for coaxial cables
• SC/ST: Push-pull and twist-lock fiber connectors

Mnemonic: “RJ BNC Fiber Connect”

Question 3(b OR) [4 marks]

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Explain IP addressing scheme with examples.

Answer:

IP Address Classes:

IP Address Structure:

• Network Part: Identifies the network
• Host Part: Identifies the device
• Subnet Mask: Separates network and host portions

Special Addresses:

• Loopback: 127.0.0.1 (localhost)
• Private: 10.x.x.x, 172.16.x.x, 192.168.x.x
• Broadcast: All host bits set to 1

Example Calculation: IP: 192.168.1.100/24

• Network: 192.168.1.0
• Broadcast: 192.168.1.255

Mnemonic: “A Big Class Networks”

Question 3(c OR) [7 marks]

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Differentiate between IPv4 and IPv6.

Answer:

IPv4 vs IPv6 Comparison:

IPv4 Characteristics:

• Address Example: 192.168.1.1
• Dotted Decimal: Four octets separated by dots
• Classes: A, B, C, D, E addressing scheme
• NAT Required: Due to address exhaustion

IPv6 Characteristics:

• Address Example: 2001:0db8:85a3::8a2e:0370:7334
• Colon Notation: Eight groups of hexadecimal digits
• No Classes: Hierarchical addressing
• Auto-configuration: Stateless address configuration

IPv6 Advantages:

• Larger Address Space: Eliminates address exhaustion
• Simplified Header: Improved processing efficiency
• Built-in Security: IPSec mandatory
• Better QoS: Flow labeling for traffic prioritization

Migration Strategies:

• Dual Stack: Run both IPv4 and IPv6
• Tunneling: Encapsulate IPv6 in IPv4
• Translation: Convert between protocols

Mnemonic: “IPv6 Has More Addresses”

Question 4(a) [3 marks]

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Explain File Transfer Protocol.

Answer:

FTP Characteristics:

FTP Operations:

• Upload: PUT command transfers files to server
• Download: GET command retrieves files from server
• Directory: LIST command shows file listings

FTP Modes:

• Active Mode: Server initiates data connection
• Passive Mode: Client initiates data connection

Mnemonic: “FTP Transfers Files”

Question 4(b) [4 marks]

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Write note on DNS.

Answer:

Domain Name System (DNS):

DNS Hierarchy:

• Root Domain: Top-level (.)
• Top-Level Domain: .com, .org, .net
• Second-Level Domain: google.com
• Subdomain: www.google.com

DNS Records:

• A Record: Maps domain to IPv4 address
• AAAA Record: Maps domain to IPv6 address
• CNAME: Canonical name alias
• MX: Mail exchange server

DNS Resolution Process:

1. Local Cache: Check browser cache
2. Recursive Query: Contact DNS resolver
3. Iterative Query: Query authoritative servers

Mnemonic: “DNS Names Servers”

Question 4(c) [7 marks]

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Explain Electronic Mail.

Answer:

graph TD
    A[Email Client] --> B[SMTP Server]
    B --> C[Internet]
    C --> D[Recipient SMTP]
    D --> E[POP3/IMAP Server]
    E --> F[Recipient Client]

Email System Components:

Email Protocols:

Email Message Format:

• Header: To, From, Subject, Date
• Body: Message content
• Attachments: Binary files

SMTP vs POP3 vs IMAP:

• SMTP: Outgoing mail protocol
• POP3: Downloads mail to local device
• IMAP: Synchronizes mail across devices

Email Process:

1. Compose: User creates message
2. Send: SMTP transfers to server
3. Route: Internet routing to destination
4. Deliver: Store in recipient mailbox
5. Retrieve: POP3/IMAP download to client

Security Features:

• Encryption: Secure mail transmission
• Authentication: Verify sender identity
• Spam Filtering: Block unwanted mail

Mnemonic: “SMTP Sends, POP3 Picks, IMAP Integrates”

Question 4(a OR) [3 marks]

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Explain Web browser.

Answer:

Web Browser Functions:

Browser Components:

• User Interface: Address bar, bookmarks, navigation
• Rendering Engine: HTML/CSS interpretation
• Networking: HTTP/HTTPS communication

Popular Browsers:

• Chrome: Google’s browser
• Firefox: Mozilla’s browser
• Safari: Apple’s browser

Mnemonic: “Browser Renders Web”

Question 4(b OR) [4 marks]

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Explain Mail Protocols.

Answer:

Email Protocol Comparison:

SMTP Features:

• Push Protocol: Sender initiates transfer
• Store and Forward: Intermediate mail servers
• Text-based: ASCII command protocol

POP3 Features:

• Download and Delete: Mail removed from server
• Offline Access: Local mail storage
• Single Device: Not suitable for multiple devices

IMAP Features:

• Server Storage: Mail remains on server
• Multi-device: Access from multiple clients
• Folder Sync: Server-client synchronization

Mnemonic: “SMTP Sends, POP3 Pulls, IMAP Integrates”

Question 4(c OR) [7 marks]

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Describe TCP and UDP protocols.

Answer:

TCP vs UDP Comparison:

graph TD
    A[Transport Layer] --> B[TCP - Reliable]
    A --> C[UDP - Fast]

    B --> B1[Web, Email, FTP]
    C --> C1[DNS, Streaming, Gaming]

TCP Features:

• Three-way Handshake: SYN, SYN-ACK, ACK
• Sequence Numbers: Ordered packet delivery
• Acknowledgments: Confirms packet receipt
• Flow Control: Prevents buffer overflow
• Congestion Control: Manages network traffic

UDP Features:

• Stateless: No connection state maintained
• Best Effort: No delivery guarantee
• Low Overhead: Minimal header information
• Broadcast Support: One-to-many communication

TCP Applications:

• Web Browsing: HTTP/HTTPS
• Email: SMTP, POP3, IMAP
• File Transfer: FTP

UDP Applications:

• DNS Queries: Domain name resolution
• Streaming: Video/audio transmission
• Gaming: Real-time applications

TCP Header Fields:

• Source/Destination Port: Application identification
• Sequence Number: Packet ordering
• Window Size: Flow control

UDP Header Fields:

• Source/Destination Port: Application identification
• Length: Datagram size
• Checksum: Error detection

Mnemonic: “TCP Tries Carefully, UDP Unleashes Data”

Question 5(a) [3 marks]

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Describe Network device Bridge.

Answer:

Bridge Characteristics:

Bridge Operations:

• Learning: Records MAC addresses from frames
• Filtering: Forwards frames only when necessary
• Forwarding: Sends frames to appropriate segment

Bridge Types:

• Transparent Bridge: Automatic learning
• Source Routing: Path specified in frame

Mnemonic: “Bridge Breaks Collisions”

Question 5(b) [4 marks]

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Explain Social issues and Hacking also discuss its precautions.

Answer:

Social Issues in Networks:

Hacking Types:

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

Precautions:

• Strong Passwords: Use complex, unique passwords
• Software Updates: Keep systems patched
• Firewall: Block unauthorized access
• Antivirus: Detect and remove malware

Security Measures:

• Education: User awareness training
• Backup: Regular data backup
• Monitoring: Network traffic analysis

Mnemonic: “Secure Systems Save Societies”

Question 5(c) [7 marks]

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Explain IP Security in detail.

Answer:

graph TD
    A[IP Security - IPSec] --> B[Authentication Header - AH]
    A --> C[Encapsulating Security Payload - ESP]
    A --> D[Security Association - SA]

    B --> B1[Data Integrity]
    C --> C1[Data Confidentiality]
    D --> D1[Security Parameters]

IPSec Components:

IPSec Modes:

IPSec Protocols:

• IKE: Internet Key Exchange for key management
• ISAKMP: Internet Security Association and Key Management
• DES/3DES/AES: Encryption algorithms

Security Services:

• Authentication: Verify sender identity
• Integrity: Ensure data not modified
• Confidentiality: Encrypt data content
• Non-repudiation: Prevent denial of sending

IPSec Process:

1. Policy Definition: Define security requirements
2. Key Exchange: Establish shared keys using IKE
3. SA Establishment: Create security association
4. Data Protection: Apply AH/ESP to packets
5. Transmission: Send protected packets

Applications:

• VPN: Virtual Private Networks
• Remote Access: Secure remote connections
• Site-to-Site: Connect branch offices

Benefits:

• Transparent Security: Works at network layer
• Strong Authentication: Cryptographic verification
• Flexible Implementation: Multiple algorithms supported

Mnemonic: “IPSec Authenticates, Encrypts, Secures”

Question 5(a OR) [3 marks]

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Explain wireless LAN.

Answer:

Wireless LAN Characteristics:

WLAN Components:

• Access Point: Central wireless hub
• Wireless Clients: Laptops, phones, tablets
• SSID: Network identifier

WLAN Standards:

• 802.11a: 54 Mbps, 5 GHz
• 802.11g: 54 Mbps, 2.4 GHz
• 802.11n: 600 Mbps, MIMO

Mnemonic: “Wireless Waves Work”

Question 5(b OR) [4 marks]

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Differentiate between symmetric and asymmetric encryption algorithms

Answer:

Encryption Algorithm Comparison:

Symmetric Encryption:

• Same Key: Encryption and decryption use same key
• Faster Processing: Efficient for large data
• Key Management: Challenge in key distribution

Asymmetric Encryption:

• Key Pair: Public key encrypts, private key decrypts
• Digital Signatures: Non-repudiation support
• Secure Communication: No prior key exchange needed

Applications:

• Symmetric: Bulk data encryption, disk encryption
• Asymmetric: Key exchange, digital certificates

Mnemonic: “Symmetric Same, Asymmetric Pair”

Question 5(c OR) [7 marks]

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

Answer:

IT Act 2008 Key Provisions:

graph TD
    A[IT Act 2008] --> B[Cyber Crimes]
    A --> C[Data Protection]
    A --> D[Digital Signatures]
    A --> E[Penalties]

    B --> B1[Hacking, Identity Theft]
    C --> C1[Sensitive Personal Data]
    D --> D1[Legal Validity]
    E --> E1[Imprisonment + Fine]

Major Amendments:

Key Features:

• Extraterritorial Jurisdiction: Applies to offenses outside India affecting Indian computers
• Cyber Appellate Tribunal: Specialized adjudication body
• Compensation: Damages up to ₹5 crore for data breach

Data Protection Provisions:

• Sensitive Personal Data: Special protection for financial, health data
• Reasonable Security: Organizations must implement adequate measures
• Breach Notification: Mandatory reporting of security incidents

Digital Signature Framework:

• Legal Validity: Electronic signatures legally recognized
• Certification Authority: Licensed bodies issue digital certificates
• Non-repudiation: Prevents denial of electronic transactions

Cybercrime Categories:

• Computer Related Offenses: Unauthorized access, data theft
• Communication Offenses: Obscene content, cyber stalking
• Identity Crimes: Impersonation, fraud

Law Enforcement Powers:

• Search and Seizure: Authority to examine computer systems
• Preservation Orders: Require data retention for investigation
• Blocking Orders: Remove offensive content from internet

Industry Impact:

• Compliance Requirements: Organizations must adopt security measures
• Liability Framework: Clear responsibilities for service providers
• Business Process: Legal framework for e-commerce, digital transactions

Challenges:

• Technology Gap: Law struggles to keep pace with technology
• Jurisdiction Issues: Cross-border cybercrime investigation
• Privacy Concerns: Balance between security and individual rights

Recent Developments:

• Personal Data Protection Bill: Comprehensive privacy legislation
• Cybersecurity Framework: National cyber security strategy
• Digital India: Government digitization initiatives

Mnemonic: “IT Act Protects Digital India”