Introduction to IT Systems (4311602) - Summer 2023 Solution

Question 1(a) [3 marks]

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Discuss the main components of the Computer.

Answer:

Table: Main Components of Computer

Key Components:

• Hardware: Physical parts like CPU, RAM, motherboard
• Software: Programs and operating systems
• Data: Information processed by computer

Mnemonic: “I Can Make Output” (Input-CPU-Memory-Output)

Question 1(b) [4 marks]

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Explain the web browser and its type.

Answer:

A web browser is software that accesses and displays web pages from the internet.

Table: Types of Web Browsers

Features:

• Navigation: Forward, back, refresh buttons
• Bookmarks: Save favorite websites
• Tabs: Multiple pages in one window
• Security: HTTPS support, popup blockers

Mnemonic: “Browse Safely Online” (Bookmarks-Security-Online)

Question 1(c) [7 marks]

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Explain LAN, MAN and WAN with example.

Answer:

Table: Network Types Comparison

Detailed Explanation:

LAN (Local Area Network):

• Coverage: Within building or small area
• Technology: Ethernet, Wi-Fi
• Example: Computer lab, home network

MAN (Metropolitan Area Network):

• Coverage: Across city or metropolitan area
• Technology: Fiber optic, microwave
• Example: City-wide cable internet

WAN (Wide Area Network):

• Coverage: Multiple cities/countries
• Technology: Satellite, fiber optic
• Example: Internet, bank ATM networks

Diagram:

graph TD
    A[LAN - Building] --> B[MAN - City]
    B --> C[WAN - Global]
    A --> D[Office Network]
    B --> E[City Cable TV]
    C --> F[Internet]

Mnemonic: “Local Metro World” (LAN-MAN-WAN)

Question 1(c OR) [7 marks]

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Difference between DOS and Unix Operating system.

Answer:

Table: DOS vs Unix Comparison

Key Differences:

DOS (Disk Operating System):

• Architecture: 16-bit, single-user
• Memory: Limited to 640KB conventional
• Commands: DIR, COPY, DEL
• File naming: 8.3 format limitation

Unix:

• Architecture: 32/64-bit, multi-user
• Memory: Advanced memory management
• Commands: ls, cp, rm, grep
• File naming: Case-sensitive, long names

Examples:

• DOS: MS-DOS, PC-DOS
• Unix: Linux, Solaris, AIX

Mnemonic: “DOS Simple, Unix Powerful” (Single vs Multi-user)

Question 2(a) [3 marks]

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List out features of operating system.

Answer:

Table: Operating System Features

Core Features:

• User Interface: GUI or command line
• Security: User authentication, access control
• Multitasking: Run multiple programs simultaneously
• Resource Allocation: CPU, memory distribution

Mnemonic: “Please Manage Files Properly” (Process-Memory-File-Device)

Question 2(b) [4 marks]

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Define half duplex and full duplex transmission modes.

Answer:

Table: Transmission Modes Comparison

Definitions:

Half Duplex:

• Communication: Two-way but not simultaneous
• Example: Radio communication, old Ethernet hubs
• Limitation: Turn-taking required

Full Duplex:

• Communication: Two-way simultaneous
• Example: Modern Ethernet, telephone calls
• Advantage: No waiting time

Diagram:

Mnemonic: “Half waits, Full flows” (Half=waiting, Full=simultaneous)

Question 2(c) [7 marks]

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Difference between open source and proprietary software.

Answer:

Table: Open Source vs Proprietary Software

Detailed Comparison:

Open Source Software:

• Definition: Source code publicly available
• Licensing: GPL, MIT, Apache licenses
• Benefits: Cost-effective, customizable, transparent
• Examples: LibreOffice, GIMP, MySQL

Proprietary Software:

• Definition: Owned by individual/company
• Licensing: End User License Agreement (EULA)
• Benefits: Professional support, guaranteed updates
• Examples: Adobe Photoshop, Oracle Database

Advantages & Disadvantages:

Open Source Pros: Free, flexible, community support Open Source Cons: Limited professional support

Proprietary Pros: Professional support, warranty Proprietary Cons: Expensive, vendor lock-in

Mnemonic: “Open = Free to See, Proprietary = Pay to Use”

Question 2(a OR) [3 marks]

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Differentiate between RAM and ROM.

Answer:

Table: RAM vs ROM Comparison

Key Differences:

• Purpose: RAM for temporary storage, ROM for permanent
• Cost: RAM more expensive per GB
• Usage: RAM for programs, ROM for firmware

Mnemonic: “RAM Runs, ROM Remembers” (temporary vs permanent)

Question 2(b OR) [4 marks]

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Explain AND logic gate with Example.

Answer:

AND Gate Definition: Output is HIGH only when ALL inputs are HIGH.

Truth Table:

Symbol:

Example Applications:

• Security System: Door opens only with key AND card
• Car Starting: Engine starts with key AND foot on brake
• Boolean Expression: Y = A · B or Y = A ∧ B

Real-life Example: Washing machine starts only when door is closed AND power button is pressed.

Mnemonic: “ALL inputs True = Output True”

Question 2(c OR) [7 marks]

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Explain the Ethernet Cable Color code.

Answer:

Standard: TIA/EIA-568B Color Code

Table: Wire Color Sequence

Cable Types:

Straight-Through Cable (568B both ends):

• Use: Computer to switch/hub
• Color sequence: Same on both ends

Cross-Over Cable (568A one end, 568B other):

• Use: Computer to computer direct
• Pins swapped: 1↔3, 2↔6

Wiring Diagram:

Preparation Steps:

1. Strip outer jacket (1 inch)
2. Arrange wires in color order
3. Cut wires evenly
4. Insert into RJ-45 connector
5. Crimp with crimping tool

Mnemonic: “White Orange, Orange, White Green, Blue, White Blue, Green, White Brown, Brown”

Question 3(a) [3 marks]

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Compare wired and Wireless Communication.

Answer:

Table: Wired vs Wireless Communication

Key Points:

• Wired: Reliable, fast, secure but limited mobility
• Wireless: Mobile, flexible but security concerns

Mnemonic: “Wires are Fast, Wireless is Free” (speed vs mobility)

Question 3(b) [4 marks]

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Discuss the different types of computer systems.

Answer:

Table: Computer System Types

Classifications:

By Size & Power:

• Supercomputer: Scientific calculations, research
• Mainframe: Large organizations, concurrent users
• Personal Computer: Individual users, office work
• Embedded Systems: Specific functions (washing machines)

By Purpose:

• General Purpose: Versatile, multiple applications
• Special Purpose: Dedicated tasks (ATM, gaming console)

Mnemonic: “Super Main Mini Micro” (decreasing size order)

Question 3(c) [7 marks]

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Write short note on TDM, FDM, and OFDM.

Answer:

Multiplexing Techniques for Efficient Communication

Table: Multiplexing Comparison

Time Division Multiplexing (TDM):

• Principle: Each user gets fixed time slot
• Implementation: Sequential data transmission
• Example: Digital telephone systems, GSM
• Advantage: Efficient use of bandwidth

Frequency Division Multiplexing (FDM):

• Principle: Each user gets unique frequency band
• Implementation: Simultaneous transmission
• Example: FM radio, cable TV
• Advantage: No timing coordination needed

Orthogonal Frequency Division Multiplexing (OFDM):

• Principle: Multiple orthogonal subcarriers
• Implementation: Parallel data streams
• Example: Wi-Fi (802.11), LTE, DSL
• Advantage: High spectral efficiency, robust against interference

Diagram:

graph TD
    A[Data Stream] --> B[TDM - Time Slots]
    A --> C[FDM - Frequency Bands]
    A --> D[OFDM - Multiple Carriers]
    B --> E["T1|T2|T3|T4"]
    C --> F[F1 + F2 + F3 + F4]
    D --> G[Orthogonal Subcarriers]

Applications:

• TDM: ISDN, T1/E1 lines
• FDM: Analog TV, radio
• OFDM: Modern wireless systems

Mnemonic: “Time Frequency Orthogonal” (TDM-FDM-OFDM)

Question 3(a OR) [3 marks]

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Discuss FSK and PSK.

Answer:

Digital Modulation Techniques

Table: FSK vs PSK

FSK (Frequency Shift Keying):

• Principle: Different frequencies for 0 and 1
• Implementation: f1 for ‘0’, f2 for ‘1’
• Example: Computer modems, RFID

PSK (Phase Shift Keying):

• Principle: Phase changes represent data
• Implementation: 0° for ‘0’, 180° for ‘1’
• Example: Wi-Fi, satellite communication

Mnemonic: “Frequency Shifts, Phase Shifts” (FSK-PSK)

Question 3(b OR) [4 marks]

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Differentiate between Multitasking and Multi programming OS.

Answer:

Table: Multitasking vs Multiprogramming

Multitasking:

• Definition: Multiple tasks run seemingly simultaneously
• Method: Time sharing with quick switching
• User Experience: Interactive, responsive
• Types: Preemptive, cooperative

Multiprogramming:

• Definition: Multiple programs in memory
• Method: CPU switches when I/O operations occur
• User Experience: Batch job processing
• Purpose: CPU utilization improvement

Mnemonic: “Tasks are Interactive, Programs are Batched”

Question 3(c OR) [7 marks]

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Write short note on network topologies.

Answer:

Network Topology Types and Characteristics

Table: Topology Comparison

Detailed Descriptions:

Bus Topology:

• Structure: Single backbone cable
• Termination: Required at both ends
• Example: Early Ethernet (10BASE2)
• Failure Impact: Cable break stops entire network

Star Topology:

• Structure: Central switch/hub with spokes
• Scalability: Easy to add/remove nodes
• Example: Modern Ethernet networks
• Failure Impact: Only affected node fails

Ring Topology:

• Structure: Nodes connected in circle
• Data Flow: Unidirectional token passing
• Example: Token Ring, FDDI
• Failure Impact: Single break stops network

Mesh Topology:

• Structure: Every node connected to every other
• Types: Full mesh, partial mesh
• Example: Internet backbone, military networks
• Reliability: Multiple paths available

Hybrid Topology:

• Structure: Combination of topologies
• Example: Star-bus, star-ring
• Flexibility: Best features of each type

Diagram:

graph TD
    A[Network Topologies] --> B[Bus]
    A --> C[Star]
    A --> D[Ring]
    A --> E[Mesh]
    A --> F[Hybrid]
    
    B --> G[Linear Connection]
    C --> H[Central Hub]
    D --> I[Circular Connection]
    E --> J[Full Interconnection]
    F --> K[Mixed Structure]

Selection Criteria:

• Cost: Bus < Star < Ring < Mesh
• Reliability: Bus < Ring < Star < Mesh
• Scalability: Ring < Bus < Star < Mesh

Mnemonic: “Bus Star Ring Mesh Hybrid” (increasing complexity)

Question 4(a) [3 marks]

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Explain Switch.

Answer:

Network Switch Definition and Functions

Table: Switch Characteristics

Key Features:

• MAC Address Table: Learns and stores device addresses
• Full Duplex: Simultaneous send/receive
• Dedicated Bandwidth: Each port gets full bandwidth
• VLAN Support: Virtual network segregation

Functions:

• Frame Forwarding: Sends data to specific port
• Address Learning: Builds MAC address table
• Loop Prevention: Spanning Tree Protocol

Mnemonic: “Switch Learns MAC Addresses”

Question 4(b) [4 marks]

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Define Cyberthreat with an example.

Answer:

Cyberthreat Definition: Malicious attempt to damage, disrupt, or gain unauthorized access to computer systems.

Table: Cyberthreat Types

Example - Phishing Attack:

• Method: Fake email from “bank”
• Request: Login credentials
• Result: Account compromise
• Prevention: Verify sender authenticity

Common Indicators:

• Suspicious emails: Unknown senders, urgent requests
• Unusual system behavior: Slow performance, pop-ups
• Unauthorized access: Changed passwords, new files

Mnemonic: “Cyber Criminals Create Chaos” (threats cause damage)

Question 4(c) [7 marks]

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Compare TCP/IP and OSI networking models.

Answer:

Table: TCP/IP vs OSI Model Comparison

Key Differences:

OSI Model (7 layers):

• Purpose: Theoretical reference model
• Development: ISO standard
• Layers: Clearly separated functions
• Usage: Educational, troubleshooting

TCP/IP Model (4 layers):

• Purpose: Practical implementation
• Development: DARPA/Internet
• Layers: Combined functionality
• Usage: Internet, real networks

Advantages:

OSI Model:

• Standardization: Universal reference
• Troubleshooting: Layer-by-layer analysis
• Education: Clear concept separation

TCP/IP Model:

• Simplicity: Fewer layers
• Practicality: Internet-proven
• Flexibility: Protocol independence

Protocols Examples:

• OSI: Conceptual framework
• TCP/IP: HTTP, FTP, TCP, UDP, IP

Diagram:

graph TD
    A[OSI - 7 Layers] --> B[Application]
    A --> C[Presentation]  
    A --> D[Session]
    A --> E[Transport]
    A --> F[Network]
    A --> G[Data Link]
    A --> H[Physical]
    
    I[TCP/IP - 4 Layers] --> J[Application]
    I --> K[Transport]
    I --> L[Internet]
    I --> M[Network Access]

Mnemonic: “OSI is Perfect Theory, TCP/IP is Practical Reality”

Question 4(a OR) [3 marks]

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Write main objectives of cyber security.

Answer:

Table: Cyber Security Objectives (CIA Triad)

Additional Objectives:

• Authentication: Verify user identity
• Authorization: Control access rights
• Non-repudiation: Prevent denial of actions

Mnemonic: “CIA protects data” (Confidentiality-Integrity-Availability)

Question 4(b OR) [4 marks]

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List out different types of networking devices used in the networking.

Answer:

Table: Networking Devices

Functions:

• Connectivity: Hub, switch, bridge
• Routing: Router, gateway
• Security: Firewall, proxy
• Wireless: Access point, wireless router

Mnemonic: “Hubs Switch Routes Bridges Gateways”

Question 4(c OR) [7 marks]

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Write different types of security attacks.

Answer:

Classification of Security Attacks

Table: Attack Types and Characteristics

Detailed Attack Categories:

1. Network Attacks:

• Man-in-the-Middle: Intercept communication
• DDoS: Overwhelm server with traffic
• Packet Sniffing: Capture network data
• IP Spoofing: Fake source addresses

2. Application Attacks:

• SQL Injection: Database manipulation
• Cross-site Scripting (XSS): Web vulnerability
• Buffer Overflow: Memory corruption
• Zero-day Exploits: Unknown vulnerabilities

3. Malware Attacks:

• Virus: Self-replicating code
• Worm: Network-spreading malware
• Trojan: Disguised malicious software
• Ransomware: Data encryption for payment

4. Social Engineering:

• Phishing: Fake emails/websites
• Pretexting: False scenarios
• Baiting: Malicious downloads
• Tailgating: Physical access following

5. Cryptographic Attacks:

• Brute Force: Try all combinations
• Dictionary Attack: Common passwords
• Rainbow Tables: Pre-computed hashes
• Side-channel: Information leakage

Attack Vectors:

• External: Internet-based attacks
• Internal: Insider threats
• Physical: Direct hardware access
• Wireless: Wi-Fi vulnerabilities

Prevention Strategies:

• Technical: Firewalls, antivirus, encryption
• Administrative: Policies, procedures
• Physical: Locks, surveillance
• Education: User awareness training

Mnemonic: “Network Application Malware Social Crypto” (attack categories)

Question 5(a) [3 marks]

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Calculate binary of (5AB.4) hexadecimal number.

Answer:

Hexadecimal to Binary Conversion

Method: Convert each hex digit to 4-bit binary

Table: Hex to Binary Conversion

Step-by-step Conversion:

• 5 → 0101
• A → 1010
• B → 1011
• . → . (decimal point)
• 4 → 0100

Final Answer: (5AB.4)₁₆ = (010110101011.0100)₂

Simplified: (10110101011.01)₂

Mnemonic: “Each Hex = 4 Bits”

Question 5(b) [4 marks]

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List out the main features of Digi-Locker, e-rupi.

Answer:

Table: Digital Platform Features

Digi-Locker Features:

• Digital Wallet: Store documents in cloud
• Authentication: Aadhaar-based verification
• Integration: Government department access
• Sharing: Secure document sharing

e-RUPI Features:

• Prepaid Voucher: Purpose-specific payments
• Contact-less: QR code/SMS based
• Security: No personal/bank details shared
• Usage: Healthcare, education, welfare schemes

Mnemonic: “Digi Stores, e-RUPI Pays” (storage vs payment)

Question 5(c) [7 marks]

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Describe different generations of a computer system.

Answer:

Computer Generations Evolution

Table: Computer Generations Comparison

Detailed Description:

First Generation (1940-1956):

• Technology: Vacuum tubes for logic/memory
• Programming: Machine language, punch cards
• Characteristics: Large, expensive, unreliable
• Heat: Generated enormous heat
• Examples: ENIAC (30 tons), UNIVAC I

Second Generation (1956-1963):

• Technology: Transistors replaced vacuum tubes
• Programming: Assembly language, FORTRAN, COBOL
• Improvements: Smaller, faster, more reliable
• Memory: Magnetic core memory
• Examples: IBM 1401, Honeywell 400

Third Generation (1964-1971):

• Technology: Integrated Circuits (ICs)
• Programming: High-level languages
• Features: Operating systems, multiprocessing
• Size: Mini-computer emergence
• Examples: IBM System/360, PDP-8

Fourth Generation (1971-1980s):

• Technology: Microprocessors (CPU on chip)
• Development: Personal computers born
• Features: GUI, networking capabilities
• Storage: Floppy disks, hard drives
• Examples: Intel 8080, Apple II, IBM PC

Fifth Generation (1980s-Present):

• Technology: AI, parallel processing, VLSI
• Features: Internet, multimedia, mobile computing
• Characteristics: User-friendly, portable, powerful
• Current: Smartphones, tablets, cloud computing
• Examples: Modern laptops, smartphones, supercomputers

Key Innovations by Generation:

• 1st: Electronic computing
• 2nd: Stored programs
• 3rd: Operating systems
• 4th: Personal computing
• 5th: Internet and AI

Diagram:

timeline
    title Computer Generations
    1940-1956 : First Generation
              : Vacuum Tubes
              : Room-sized
    1956-1963 : Second Generation
              : Transistors
              : Smaller size
    1964-1971 : Third Generation
              : Integrated Circuits
              : Minicomputers
    1971-1980s : Fourth Generation
               : Microprocessors
               : Personal Computers
    1980s-Present : Fifth Generation
                  : AI & Internet
                  : Mobile Computing

Mnemonic: “Vacuum Transistor IC Micro AI” (technology progression)

Question 5(a OR) [3 marks]

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Write Difference between Data and Information with example.

Answer:

Table: Data vs Information

Examples:

• Data: Student marks (85, 92, 78, 88)
• Information: Class average is 85.75%

Characteristics:

• Data: Unorganized, raw, needs processing
• Information: Organized, meaningful, useful for decisions

Mnemonic: “Data is Raw, Information is Refined”

Question 5(b OR) [4 marks]

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Compare analog modulation and digital modulation.

Answer:

Table: Analog vs Digital Modulation

Analog Modulation:

• Types: AM (Amplitude), FM (Frequency), PM (Phase)
• Applications: Radio broadcasting, analog TV
• Advantages: Simple, lower bandwidth
• Disadvantages: Noise susceptible, quality loss

Digital Modulation:

• Types: ASK, FSK, PSK, QAM
• Applications: Wi-Fi, cellular, satellite
• Advantages: Noise resistant, error correction
• Disadvantages: Complex, higher bandwidth

Mnemonic: “Analog is Simple, Digital is Smart”

Question 5(c OR) [7 marks]

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Discuss the range of IP addresses in IPv4

Answer:

IPv4 Address Range and Classification

Table: IPv4 Address Classes

Special Address Ranges:

Private IP Ranges (RFC 1918):

• Class A: 10.0.0.0 - 10.255.255.255 (/8)
• Class B: 172.16.0.0 - 172.31.255.255 (/12)
• Class C: 192.168.0.0 - 192.168.255.255 (/16)

Reserved Addresses:

• Loopback: 127.0.0.0 - 127.255.255.255
• Link-local: 169.254.0.0 - 169.254.255.255
• Broadcast: x.x.x.255 (last address in subnet)
• Network: x.x.x.0 (first address in subnet)

Address Structure:

• Total IPv4 space: 4,294,967,296 addresses (2³²)
• Format: 32-bit address in dotted decimal
• Example: 192.168.1.100

Subnet Calculation Example:

• Network: 192.168.1.0/24
• Subnet Mask: 255.255.255.0
• Host Range: 192.168.1.1 - 192.168.1.254
• Broadcast: 192.168.1.255

CIDR Notation:

• /8: 255.0.0.0 (Class A default)
• /16: 255.255.0.0 (Class B default)
• /24: 255.255.255.0 (Class C default)
• /30: 255.255.255.252 (Point-to-point links)

IPv4 Exhaustion:

• Problem: Limited address space
• Solution: IPv6 (128-bit addresses)
• Temporary fixes: NAT, CIDR, private addressing

Diagram:

graph TD
    A[IPv4 Address Space] --> B[Class A: 1-126]
    A --> C[Class B: 128-191]  
    A --> D[Class C: 192-223]
    A --> E[Class D: 224-239 Multicast]
    A --> F[Class E: 240-255 Reserved]
    
    B --> G[Large Networks]
    C --> H[Medium Networks]
    D --> I[Small Networks]

Applications:

• Public IPs: Internet routing
• Private IPs: Internal networks
• Multicast: One-to-many communication
• Loopback: Local testing

Mnemonic: “A Big Company Delivered Everything” (Classes A-B-C-D-E)