Introduction To IT Systems (4311602) - Summer 2024 Solution

Question 1(a) [3 marks]

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Define Following Term: 1. Data 2. Information 3. Knowledge

Answer:

Table: Data, Information, and Knowledge Definitions

• Data: Basic building blocks without interpretation
• Information: Data processed to provide meaningful context
• Knowledge: Information enhanced with human insight and wisdom

Mnemonic: “DIK - Data Is Knowledge’s foundation”

Question 1(b) [4 marks]

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Explain Primary Memory in brief.

Answer:

Table: Primary Memory Characteristics

• RAM (Random Access Memory): Main working memory for current programs
• Cache Memory: Ultra-fast memory between CPU and RAM
• Volatile Nature: Data disappears when computer shuts down
• Direct CPU Access: CPU can directly read/write data

Mnemonic: “Primary is Fast but Forgetful”

Question 1(c) [7 marks]

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Explain types of real time OS with example.

Answer:

Table: Real-Time Operating System Types

graph TD
    A[Real-Time OS] --> B[Hard Real-Time]
    A --> C[Soft Real-Time]
    A --> D[Firm Real-Time]
    B --> E[Critical Systems]
    C --> F[Multimedia Apps]
    D --> G[Industrial Control]

• Hard Real-Time: Missing deadline causes system failure
• Soft Real-Time: Delayed response reduces performance but system continues
• Deterministic Response: Predictable timing behavior is essential

Mnemonic: “HSF - Hard, Soft, Firm timing requirements”

Question 1(c OR) [7 marks]

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Describe Linux architecture and discuss the mode of the operation of Linux

Answer:

Linux Architecture Diagram:

graph TB
    A[User Applications] --> B[System Libraries]
    B --> C[System Call Interface]
    C --> D[Linux Kernel]
    D --> E[Hardware Layer]
    
    subgraph "Kernel Space"
    D
    end
    
    subgraph "User Space"
    A
    B
    C
    end

Table: Linux Operation Modes

• Layered Architecture: Clear separation between user and system components
• Mode Switching: CPU switches between user and kernel modes
• System Calls: Interface for user programs to access kernel services
• Security: User mode prevents direct hardware access

Mnemonic: “LUSK - Linux Uses Safe Kernel protection”

Question 2(a) [3 marks]

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Describe XOR gate with its truth table.

Answer:

XOR Gate Symbol:

Truth Table:

• Exclusive OR: Output is 1 when inputs are different
• Logic Function: A ⊕ B = A’B + AB'
• Applications: Half adder, parity checker, encryption

Mnemonic: “XOR - eXclusive OR gives 1 for different inputs”

Question 2(b) [4 marks]

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Solve following. i) (4C6)₁₆ = ()₂ = ()₁₀ ii) (186)₁₀ = ()₈ = ()₂

Answer:

Solution Table:

Detailed Solutions:

i) (4C6)₁₆ = (10011000110)₂ = (1222)₁₀

• 4 = 0100, C = 1100, 6 = 0110
• Combined: 010011000110 = 10011000110₂
• Decimal: 1×2¹⁰ + 0×2⁹ + 0×2⁸ + 1×2⁷ + 1×2⁶ + 0×2⁵ + 0×2⁴ + 0×2³ + 1×2² + 1×2¹ + 0×2⁰ = 1222₁₀

ii) (186)₁₀ = (272)₈ = (10111010)₂

• Octal: 186 ÷ 8 = 23 remainder 2, 23 ÷ 8 = 2 remainder 7, 2 ÷ 8 = 0 remainder 2 → 272₈
• Binary: 186 = 128 + 32 + 16 + 8 + 2 = 10111010₂

Mnemonic: “HDB - Hex, Decimal, Binary conversions”

Question 2(c) [7 marks]

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Illustrate following OS i) Network Operating System ii) Mobile Operating System

Answer:

Table: Operating System Comparison

graph LR
    A[Network OS] --> B[File Server]
    A --> C[Print Server]
    A --> D[Application Server]
    
    E[Mobile OS] --> F[Touch Interface]
    E --> G[App Store]
    E --> H[Battery Management]

i) Network Operating System:

• Multi-user Support: Handles multiple concurrent users
• Resource Sharing: Files, printers, applications shared across network
• Security Management: User authentication and access control

ii) Mobile Operating System:

• Touch-Optimized: Designed for finger-based interaction
• Power Management: Efficient battery usage
• App Ecosystem: Centralized app distribution and management

Mnemonic: “NOS for Networks, MOS for Mobility”

Question 2(a OR) [3 marks]

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Draw Logic circuit of OR gate and NOT gate using only NAND gate.

Answer:

OR Gate using NAND:

NOT Gate using NAND:

Truth Verification Table:

• NAND Universal: Can implement any logic function
• De Morgan’s Law: (A’·B’)’ = A+B

Mnemonic: “NAND is Universal - can make all gates”

Question 2(b OR) [4 marks]

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i) Convert Binary number into Decimal number: (i) 11101 (ii) 10011 ii) Convert decimal number into binary number: (i) 19 (ii) 64

Answer:

Conversion Table:

Detailed Solutions:

i) Binary to Decimal:

• 11101₂ = 16 + 8 + 4 + 0 + 1 = 29₁₀
• 10011₂ = 16 + 0 + 0 + 2 + 1 = 19₁₀

ii) Decimal to Binary:

• 19 ÷ 2 = 9 remainder 1, 9 ÷ 2 = 4 remainder 1, 4 ÷ 2 = 2 remainder 0, 2 ÷ 2 = 1 remainder 0, 1 ÷ 2 = 0 remainder 1 → 10011₂
• 64 ÷ 2 = 32 remainder 0… → 1000000₂

Mnemonic: “Powers of 2 for Binary to Decimal”

Question 2(c OR) [7 marks]

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Explain Open-source software and Proprietary software. Give at least five examples of both the types of software.

Answer:

Table: Software Type Comparison

Software Examples:

pie title Software Distribution
    "Open-Source" : 40
    "Proprietary" : 60

Open-Source Characteristics:

• Freedom to Modify: Users can change source code
• Community Development: Collaborative improvement
• Transparency: All code is visible and auditable

Proprietary Characteristics:

• Commercial Model: Revenue through licensing
• Professional Support: Dedicated customer service
• Quality Assurance: Rigorous testing and validation

Mnemonic: “FOSS is Free, Open, Shared, Supported by community”

Question 3(a) [3 marks]

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Define 1. Modulation 2. Multiplexing

Answer:

Definition Table:

• Modulation: Changes amplitude, frequency, or phase of carrier wave
• Multiplexing: Allows multiple users to share same communication medium
• Signal Processing: Both techniques improve communication efficiency

Mnemonic: “MM - Modulation Modifies, Multiplexing Merges”

Question 3(b) [4 marks]

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Explain star topology.

Answer:

Star Topology Diagram:

Table: Star Topology Features

• Central Hub: All communication passes through central device
• Easy Troubleshooting: Problems isolated to individual connections
• Higher Cost: Requires more cable than bus topology
• Single Point of Failure: Hub failure affects entire network

Mnemonic: “STAR - Single point, Troubleshooting easy, All through hub, Reliable”

Question 3(c) [7 marks]

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Prepare a short note on Time Division Multiplexing (TDM)

Answer:

TDM Concept Diagram:

gantt
    title Time Division Multiplexing
    dateFormat X
    axisFormat %s
    
    section Channel A
    Slot 1    :0, 1
    Slot 4    :3, 4
    Slot 7    :6, 7
    
    section Channel B  
    Slot 2    :1, 2
    Slot 5    :4, 5
    Slot 8    :7, 8
    
    section Channel C
    Slot 3    :2, 3
    Slot 6    :5, 6
    Slot 9    :8, 9

Table: TDM Characteristics

TDM Types:

• Synchronous TDM: Fixed time slots regardless of data availability
• Asynchronous TDM: Dynamic slot allocation based on demand
• Statistical TDM: Slots allocated on statistical basis

Advantages:

• Fair Sharing: Equal time allocation for all users
• No Signal Interference: Time-based separation prevents conflicts

Mnemonic: “TDM - Time Divides Medium fairly”

Question 3(a OR) [3 marks]

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Explain Amplitude Modulation (AM).

Answer:

AM Signal Diagram:

Table: AM Characteristics

• Carrier Wave: High frequency signal that carries information
• Modulation Index: Determines depth of amplitude variation
• Applications: AM radio broadcasting, aircraft communication

Mnemonic: “AM - Amplitude Modifies with message”

Question 3(b OR) [4 marks]

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Describe DNS.

Answer:

DNS Hierarchy:

graph TD
    A[Root .] --> B[Top Level .com]
    A --> C[Top Level .org]
    B --> D[google.com]
    B --> E[microsoft.com]
    D --> F[www.google.com]
    D --> G[mail.google.com]

Table: DNS Components

• Name Resolution: Converts domain names to IP addresses
• Hierarchical Structure: Root, TLD, second-level domains
• Distributed Database: No single point of failure
• Caching: Improves performance by storing recent lookups

Mnemonic: “DNS - Domain Name System translates addresses”

Question 3(c OR) [7 marks]

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Describe following 1. Serial Communication 2. Synchronous Transmission

Answer:

Communication Types Diagram:

graph LR
    A[Data Communication] --> B[Serial]
    A --> C[Parallel]
    B --> D[Synchronous]
    B --> E[Asynchronous]

Table: Communication Comparison

1. Serial Communication:

• Single Wire: Data transmitted bit by bit over single channel
• Cost Effective: Requires fewer wires than parallel
• Long Distance: Less susceptible to noise and interference
• Error Detection: Built-in mechanisms for data integrity

2. Synchronous Transmission:

• Clock Synchronization: Separate clock signal or embedded timing
• Block Transmission: Data sent in continuous blocks
• Higher Efficiency: No start/stop bits needed
• Complex Hardware: Requires synchronized clocks

Mnemonic: “Serial is Sequential, Synchronous is Simultaneous”

Question 4(a) [3 marks]

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Differentiate Mesh and Bus topology.

Answer:

Topology Comparison Table:

Mesh Topology:

Bus Topology:

• Mesh Advantages: Redundant paths, high reliability
• Bus Advantages: Simple installation, cost-effective
• Cable Requirements: Mesh needs n(n-1)/2 connections, Bus needs single cable

Mnemonic: “Mesh is Many connections, Bus is Basic single line”

Question 4(b) [4 marks]

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Compare FDM and TDM.

Answer:

Table: FDM vs TDM Comparison

graph TB
    A[Multiplexing Techniques] --> B[FDM]
    A --> C[TDM]
    B --> D[Radio Broadcasting]
    B --> E[Cable TV]
    C --> F[Digital Telephony]
    C --> G[Computer Networks]

FDM Characteristics:

• Frequency Separation: Each signal allocated different frequency band
• Simultaneous Transmission: All signals transmitted at same time
• Guard Bands: Prevent interference between channels

TDM Characteristics:

• Time Separation: Each signal allocated different time slot
• Sequential Transmission: Signals transmitted one after another
• Precise Timing: Requires synchronized clocks

Mnemonic: “FDM uses Frequency, TDM uses Time”

Question 4(c) [7 marks]

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Draw and illustrate OSI reference model.

Answer:

OSI Model Diagram:

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

Table: OSI Layer Functions

Key Features:

• Layered Architecture: Each layer has specific responsibilities
• Protocol Independence: Layers can be modified independently
• Standardization: Common framework for network communication
• Encapsulation: Each layer adds its own header

Mnemonic: “All People Seem To Need Data Processing”

Question 4(a OR) [3 marks]

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Describe Hub in brief.

Answer:

Hub Diagram:

Table: Hub Characteristics

• Shared Bandwidth: All connected devices share total bandwidth
• Half-Duplex: Cannot send and receive simultaneously
• Security Issues: All devices receive all transmitted data
• Obsolete Technology: Replaced by switches in modern networks

Mnemonic: “Hub is Half-duplex, shares Bandwidth”

Question 4(b OR) [4 marks]

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Compare STP and UTP.

Answer:

Table: STP vs UTP Cable Comparison

Cable Structure:

STP Advantages:

• Better Noise Immunity: Shield blocks electromagnetic interference
• Higher Data Rates: Supports faster transmission speeds
• Secure Transmission: Less susceptible to eavesdropping

UTP Advantages:

• Cost Effective: Cheaper than STP
• Easy Installation: No grounding requirements
• Flexibility: More flexible and easier to handle

Mnemonic: “STP is Shielded but Pricey, UTP is Unshielded but Popular”

Question 4(c OR) [7 marks]

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Distinguish LAN, MAN, WAN.

Answer:

Network Size Comparison:

graph TB
    A[Computer Networks] --> B[LAN - Local Area Network]
    A --> C[MAN - Metropolitan Area Network]  
    A --> D[WAN - Wide Area Network]
    
    B --> E[Building/Campus]
    C --> F[City/Metropolitan Area]
    D --> G[Country/Continent]

Table: Network Type Comparison

Detailed Characteristics:

LAN (Local Area Network):

• High Speed: Fast data transmission within small area
• Low Cost: Inexpensive to set up and maintain
• Private Ownership: Usually owned by single organization

MAN (Metropolitan Area Network):

• City-wide Coverage: Spans across metropolitan area
• Medium Speed: Moderate transmission speeds
• Mixed Ownership: Can be public or private

WAN (Wide Area Network):

• Global Coverage: Spans countries and continents
• Variable Speed: Depends on connection type
• Public Infrastructure: Uses public telecommunication networks

Mnemonic: “LAN is Local, MAN is Metropolitan, WAN is Wide”

Question 5(a) [3 marks]

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Explain Denial of Service Attack.

Answer:

DoS Attack Diagram:

graph LR
    A[Attacker] --> B[Multiple Requests]
    B --> C[Target Server]
    C --> D[Server Overwhelmed]
    D --> E[Service Unavailable]

Table: DoS Attack Types

• Objective: Make services unavailable to legitimate users
• Methods: Traffic flooding, resource exhaustion, exploit vulnerabilities
• Impact: Service disruption, financial loss, reputation damage
• Prevention: Firewalls, load balancers, intrusion detection systems

Mnemonic: “DoS Denies Others Service”

Question 5(b) [4 marks]

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i) Classify data transmission ii) Write down use of Terminator in Bus Topology.

Answer:

i) Data Transmission Classification:

graph TD
    A[Data Transmission] --> B[Direction]
    A --> C[Timing]
    A --> D[Mode]
    
    B --> E[Simplex]
    B --> F[Half-Duplex]
    B --> G[Full-Duplex]
    
    C --> H[Synchronous]
    C --> I[Asynchronous]
    
    D --> J[Serial]
    D --> K[Parallel]

ii) Terminator in Bus Topology:

Table: Terminator Functions

• Prevention of Reflection: Stops signals from bouncing back
• Signal Quality: Maintains clean signal transmission
• Required at Both Ends: Bus topology needs terminators at both cable ends
• Resistance Value: Usually 50 ohms for Ethernet networks

Mnemonic: “Terminator Stops signal Travel”

Question 5(c) [7 marks]

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Describe CIA triad.

Answer:

CIA Triad Diagram:

graph TD
    A[CIA Triad] --> B[Confidentiality]
    A --> C[Integrity]
    A --> D[Availability]
    
    B --> E[Encryption]
    B --> F[Access Control]
    
    C --> G[Hash Functions]
    C --> H[Digital Signatures]
    
    D --> I[Redundancy]
    D --> J[Backup Systems]

Table: CIA Triad Components

Detailed Explanation:

Confidentiality:

• Data Protection: Only authorized users can access information
• Privacy Measures: Encryption, authentication, access controls
• Examples: Password protection, file permissions

Integrity:

• Data Accuracy: Information remains unaltered during transmission/storage
• Verification Methods: Checksums, digital signatures, version control
• Examples: Hash functions, database constraints

Availability:

• System Accessibility: Information and services available when needed
• Reliability Measures: Redundancy, fault tolerance, disaster recovery
• Examples: Load balancing, backup systems, UPS

Mnemonic: “CIA protects - Confidentiality, Integrity, Availability”

Question 5(a OR) [3 marks]

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Define 1. Cryptography 2. Decryption

Answer:

Definition Table:

• Cryptography: Uses mathematical algorithms to transform readable data into unreadable format
• Decryption: Reverse process using keys to restore original data
• Key-based Security: Both processes rely on cryptographic keys

Mnemonic: “Crypto Conceals, Decryption Discloses”

Question 5(b OR) [4 marks]

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i) State the reason why wires are twisted in twisted pair cables. ii) Identify the layer of OSI model at which the following network devices support 1. Router 2. Bridge

Answer:

i) Twisted Pair Cable Design:

Table: Wire Twisting Benefits

ii) OSI Layer Identification:

Table: Network Devices and OSI Layers

• Wire Twisting: Each twist cancels out electromagnetic interference from adjacent wire
• Interference Cancellation: Noise affects both wires equally but in opposite directions
• Router Function: Makes routing decisions based on IP addresses
• Bridge Function: Forwards frames based on MAC addresses

Mnemonic: “Twisted wires Reduce interference, Router at layer 3, Bridge at layer 2”

Question 5(c OR) [7 marks]

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Define Cyber Attack and Explain various cyber-attacks in brief

Answer:

Cyber Attack Definition: Cyber attack is a deliberate attempt to compromise computer systems, networks, or digital devices to steal, alter, or destroy data.

Types of Cyber Attacks:

graph TD
    A[Cyber Attacks] --> B[Malware]
    A --> C[Phishing]
    A --> D[DoS/DDoS]
    A --> E[Man-in-Middle]
    A --> F[SQL Injection]
    
    B --> G[Virus, Worm, Trojan]
    C --> H[Email, Website]
    D --> I[Traffic Flooding]
    E --> J[Eavesdropping]
    F --> K[Database Attack]

Table: Cyber Attack Types

Detailed Attack Explanations:

Malware Attacks:

• Virus: Self-replicating code that attaches to files
• Worm: Standalone malware that spreads across networks
• Trojan: Disguised malware that appears legitimate

Social Engineering:

• Phishing: Fake emails requesting sensitive information
• Spear Phishing: Targeted attacks on specific individuals
• Baiting: Using attractive offers to deliver malware

Network Attacks:

• Packet Sniffing: Capturing network traffic for analysis
• Session Hijacking: Taking over user sessions
• Password Attacks: Brute force, dictionary attacks

Mnemonic: “MPDMS - Malware, Phishing, DoS, Man-in-middle, SQL injection”