💡 DSU Exam Strategy & Guidance

OSI vs TCP/IP Layers, Subnetting (VLSM, CIDR), Sliding Window Protocols (Go-Back-N, Selective Repeat), Routing Algorithms (Link State, Distance Vector), and TCP Congestion Control.

High-Yield Passing Strategy: Practice IP subnet calculations and CRC error-detection polynomial division.

Most Repeated Question Topics:

CIDR Subnetting CalculationsCRC Polynomial Error DetectionGo-Back-N vs Selective Repeat ARQDistance Vector Routing & Count-to-Infinity ProblemTCP 3-Way Handshake & Congestion Window

🔥 Most Predictable Exam Questions (2)

Guaranteed Every Year 8 Marks Module 3: Network Layer & Addressing

Q1. An organization is granted IP block 192.168.10.0/24. Design 4 subnets: Subnet A (60 hosts), Subnet B (30 hosts), Subnet C (20 hosts), Subnet D (10 hosts) using VLSM. List Subnet Address, Subnet Mask, Valid Host IP Range, and Broadcast Address for each.

Key Points: Subnet A (60 hosts): 2^6 - 2 = 62. Mask /26 (255.255.255.192). Range: .1 to .62, BC: .63. Subnet B (30 hosts): 2^5 - 2 = 30. Mask /27. Range: .65 to .94, BC: .95. Subnet C (20 hosts): Mask /27. Range: .97 to .126, BC: .127. Subnet D (10 hosts): 2^4 - 2 = 14. Mask /28. Range: .129 to .142, BC: .143.

95% Probability 8 Marks Module 2: Data Link Layer & Flow Control

Q2. Differentiate between Go-Back-N and Selective Repeat sliding window protocols. For a channel with bandwidth 1 Mbps, round trip time 40ms, and packet size 1000 bits, compute the link utilization for window size N = 4.

Key Points: Transmission time Tt = 1000 / 10^6 = 1 ms. Propagation time Tp = RTT / 2 = 20 ms. a = Tp / Tt = 20. Efficiency eta = N / (1 + 2a) = 4 / (1 + 40) = 4 / 41 = 9.76%.

🎓 Open Source Courses & Video Playlists (3)

YouTube (Gate Smashers)

Gate Smashers: Computer Networks Complete Series

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Stanford Online

Stanford CS144: Introduction to Computer Networking

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YouTube (Neso Academy)

Neso Academy: Computer Networks

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📄 Previous Year Question Papers (2)

END_SEM • 2024

End Semester Exam 2024

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END_SEM • 2023

End Semester Exam 2023

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