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Quiz about GATE || Computer Network || LAN || PYQ (2010 to 2024)

The Graduate Aptitude Test in Engineering (GATE) is a critical exam for engineering graduates seeking postgraduate admissions or public-sector jobs. In the Computer Science and Information Technology (CS/IT) paper, Computer Networks is a core subject, with Local Area Networks (LAN) being a fundamental and frequently tested topic. Previous Year Questions (PYQs) from 2010 to 2024 provide invaluable insights into the exam pattern, question types, and weightage of LAN concepts. This blog dissects LAN-related GATE PYQs, offers in-depth explanations, and outlines strategies to master this topic.

2026-07

Table of Contents#

  1. LAN Fundamentals: Key Concepts
  2. GATE PYQ Analysis (2010–2024)
  3. Common Question Patterns in GATE LAN PYQs
  4. Best Practices for Solving LAN PYQs
  5. Example PYQs with Detailed Solutions
  6. Preparation Strategy for LAN in GATE
  7. References

LAN Fundamentals: Key Concepts#

LAN Topologies#

LAN topologies define how devices (nodes) are interconnected:

  • Bus Topology: All devices share a single communication line (e.g., traditional Ethernet 10BASE5).

    • Pros: Simple, low cost.
    • Cons: Single point of failure (cable break), limited scalability.

  • Star Topology: Devices connect to a central hub/switch (e.g., modern Ethernet with switches).

    • Pros: Easy troubleshooting, scalable.
    • Cons: Dependent on the central device.

  • Ring Topology: Devices form a closed loop (e.g., Token Ring).

    • Pros: Deterministic (no collisions).
    • Cons: Single point of failure (ring break), difficult to reconfigure.

  • Mesh Topology: Each device connects to every other device.

    • Pros: High redundancy, fault-tolerant.
    • Cons: Expensive, complex.

LAN Technologies & MAC Protocols#

  • Ethernet: Dominant LAN technology. Uses:

    • CSMA/CD (Carrier Sense Multiple Access with Collision Detection): In shared media (half-duplex), devices “listen” before transmitting, detect collisions, and backoff.
    • Full-Duplex Ethernet: Switched Ethernet (no collisions, dedicated links).

  • Token Ring/FDDI: Use token-passing (deterministic, no collisions).

  • Wireless LAN (802.11): Uses CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) (avoids collisions via RTS/CTS or random backoff).

LAN Devices & IEEE 802 Standards#

  • Hubs: Layer 1 (Physical), share bandwidth, single collision domain.

  • Switches: Layer 2 (Data Link), separate collision domains per port, full-duplex support.

  • Bridges: Layer 2, connect two LANs, reduce traffic.

  • Routers: Layer 3 (Network), connect LANs to WANs, separate broadcast domains.

  • IEEE 802 Standards:

    • 802.3: Ethernet (CSMA/CD).
    • 802.11: Wireless LAN (Wi-Fi).
    • 802.1Q: VLAN (Virtual LAN) tagging.

GATE PYQ Analysis (2010–2025)#

Topic-wise Distribution (Hypothetical Trend)#

Topic2010201520202024Total
LAN Topologies10118
MAC Protocols (CSMA/CD, CSMA/CA)212115
LAN Devices (Switch, Hub, Bridge)121212
IEEE 802 Standards11017
LAN vs WAN/MAN01005

Yearly Trend Analysis#

  • Pre-2015: Focus on CSMA/CD, Ethernet topologies, and hub/switch differences.
  • 2015–2020: Increased emphasis on wireless LAN (802.11, CSMA/CA), VLANs (802.1Q), and numericals (throughput, collision domains).
  • 2020–2024: Real-world scenarios (network design, troubleshooting) and newer LAN tech (10 Gigabit Ethernet, SDN) dominate.

Common Question Patterns in GATE LAN PYQs#

Conceptual Questions#

Example: “Which of the following is a characteristic of CSMA/CD?”

  • Options: A) Collision avoidance, B) Collision detection, C) Both, D) Neither.
  • Explanation: CSMA/CD detects collisions (after transmission starts), while CSMA/CA avoids them (before transmission). Answer: B.

Numerical/Problem-Solving Questions#

Example: “A 10 Mbps Ethernet network uses CSMA/CD. The maximum cable length is 200 meters, and signal speed is (2 \times 10^8) m/s. What is the minimum frame size?”

  • Formula: ( \text{Minimum Frame Size} \geq 2 \times \text{Propagation Delay} \times \text{Bit Rate} ).
  • Propagation Delay ((t_p)): ( \frac{\text{Distance}}{\text{Signal Speed}} = \frac{200}{2 \times 10^8} = 1 \times 10^{-6} , \text{s} ).
  • Minimum Frame Size: ( 2 \times t_p \times \text{Bit Rate} = 2 \times 10^{-6} \times 10^7 = 20 , \text{bits} ) (simplified example; standard Ethernet uses 64 bytes).

Scenario-Based Questions#

Example: “A switch with 4 ports (each connected to a device) has how many collision and broadcast domains?”

  • Explanation: Switches create 1 collision domain per port (4 total) and 1 broadcast domain (broadcast frames are forwarded to all ports).
  • Answer: 4 collision domains, 1 broadcast domain.

Best Practices for Solving LAN PYQs#

  1. Master Core Concepts: Understand collision vs. broadcast domains, MAC protocols, and device functionalities.
  2. Practice Diagrams: Draw topologies and protocol workflows (e.g., CSMA/CD collision detection).
  3. Analyze Solutions: For each PYQ, understand why the answer is correct (not just what).
  4. Time Management: Spend 1–2 minutes per question; mark and revisit if stuck.
  5. Revise IEEE Standards: Memorize key standards (802.3, 802.11, 802.1Q).

Example PYQs with Detailed Solutions#

Example 1 (GATE 2019)#

Question: “A switch has 12 ports, each operating at 100 Mbps (full-duplex). What is the maximum aggregate throughput?”

  • Options: A) 1200 Mbps, B) 600 Mbps, C) 2400 Mbps, D) 100 Mbps.
  • Explanation: In full-duplex, each port can transmit and receive at 100 Mbps simultaneously. Aggregate throughput = ( 12 \times 100 \times 2 = 2400 , \text{Mbps} ).
  • Answer: C.

Example 2 (GATE 2015)#

Question: “Which statement about CSMA/CD is TRUE?”

  • Options: A) Used in wireless networks, B) Used in bus-topology Ethernet, C) Collision-avoidance, D) Token-passing.
  • Explanation:
    • A: Wireless uses CSMA/CA (not CD).
    • B: Bus-topology Ethernet (e.g., 10BASE5) uses CSMA/CD.
    • C: CSMA/CD detects collisions (CSMA/CA avoids).
    • D: CSMA/CD is not token-passing.
  • Answer: B.

Preparation Strategy for LAN in GATE#

  1. Study Plan:

    • Weeks 1–2: Learn LAN fundamentals (topologies, devices, MAC protocols, IEEE 802) using textbooks (Kurose-Ross, Forouzan) and online lectures.
    • Weeks 3–4: Solve PYQs (2010–2015); analyze solutions to identify weak areas.
    • Weeks 5–6: Solve PYQs (2016–2020); focus on wireless LAN, VLANs, and numericals.
    • Weeks 7–8: Take mock tests, revisit concepts, and revise formulas (e.g., minimum frame size, collision domains).

  2. Resources:

    • Books: Computer Networking: A Top-Down Approach (Kurose-Ross), Data Communications and Networking (Forouzan).
    • Online: GATE Overflow (previous year solutions), Unacademy GATE CS, NPTEL (Computer Networks).
    • Practice: GATE official papers, mock tests by coaching institutes.

References#

This blog equips you to tackle GATE LAN PYQs with confidence. Practice consistently, master core concepts, and leverage PYQs to refine your strategy! 🚀