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GATE · Computer Networks · Nigeria

Computer Networks for the GATE Exam — Nigerian candidates

10% of the GATE test plan. OSI and TCP/IP models, routing protocols, TCP/UDP, IP addressing, subnetting, and congestion control — approximately 10% of GATE CS. Calibrated for Nigerian candidates.

High-stakes exams reward two skills equally: knowledge and test-craft. This page focuses on both for one of the most failure-prone areas. Computer Networks sits at roughly 10% of the Graduate Aptitude Test in Engineering content distribution — Computer Networks is the most calculation-heavy GATE CS topic after Computer Organization. Subnetting, sliding-window throughput calculations, and routing-table lookups are numerically tested every year. The topic also includes conceptual questions on TCP state machines and protocol mechanisms. Pass rates for the GATE are published annually by the awarding body and vary by cohort and locale. For Nigerian candidates preparing for GATE, the calibration of study to local context matters: Nigeria has West Africa's largest exam-prep market. WAEC, JAMB, and NECO are the high-stakes national tests; IELTS and PTE are dominant migration credentials.

Pass rates for GATE (Nigeria) are published periodically by the awarding body.

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

  • !Subnetting errors — off-by-one in the number of usable hosts (subtract 2 for network and broadcast addresses)
  • !Confusing the window size in bytes vs in segments when calculating TCP throughput
  • !Applying CSMA/CD to wireless networks (CSMA/CA is used in 802.11, not CSMA/CD)
  • !Misidentifying which layer a protocol belongs to: ARP is Layer 2/3 boundary, ICMP is Layer 3, DNS is Layer 7
  • !Calculating distance-vector routing loops instead of counting-to-infinity scenarios correctly

Study tips

  • 1Drill IPv4 subnetting until it is mechanical: given an IP address and prefix length, identify the network address, broadcast address, first host, last host, and number of usable hosts.
  • 2For TCP throughput, use: throughput = window_size / RTT. Know how to adjust for slow-start and packet loss.
  • 3Memorise the OSI layer and which protocols live where. GATE asks "at which layer does X protocol operate?" in 1-mark questions.
  • 4Practice sliding-window protocol problems: given window size W and propagation delay, find channel utilisation.
  • 5Trace distance-vector and link-state routing convergence on small topologies (4–5 nodes).
  • 6In Nigeria, internet stability during GATE computer-based testing varies by centre — booking centres in Lagos, Abuja, or Port Harcourt typically delivers the best test-day experience.

Sample GATE Computer Networks questions

These sample items mirror the format and difficulty of real GATE questions. Practice with thousands more on the free Koydo question bank.

  1. 1

    A subnet mask of 255.255.255.192 (i.e., /26) gives how many usable host addresses per subnet?

    • A62Correct
    • B64
    • C126
    • D30
    Why this answer?

    (GATE CS style) /26 means 6 host bits. Total addresses = 2⁶ = 64. Usable hosts = 64 − 2 = 62 (subtract network and broadcast addresses).

  2. 2

    Which protocol resolves an IP address to a MAC address on a local network?

    • ADNS
    • BDHCP
    • CARPCorrect
    • DICMP
    Why this answer?

    (GATE CS style) ARP (Address Resolution Protocol) broadcasts a request with a target IP address; the host with that IP replies with its MAC address. DNS resolves hostnames to IP addresses; DHCP assigns IP addresses dynamically; ICMP handles error messages.

  3. 3

    In a sliding-window protocol, if the window size is W and the link propagation delay is T_p and transmission time is T_t, maximum utilisation is:

    • AW / (1 + 2T_p/T_t)Correct
    • BT_t / (T_t + T_p)
    • CW × T_t / T_p
    • DT_p / (W × T_t)
    Why this answer?

    (GATE CS style) For stop-and-wait, efficiency = 1/(1 + 2a) where a = T_p/T_t. For a window of W frames, efficiency = W/(1 + 2a) provided W ≤ 1 + 2a; otherwise efficiency approaches 1.

Frequently asked questions

Is IPv6 tested in GATE CS?
IPv6 concepts (128-bit addressing, header simplification, extension headers, no broadcast) appear occasionally as conceptual questions. IPv4 subnetting is far more frequently tested numerically.
How important is the TCP three-way handshake for GATE?
The TCP connection establishment (SYN, SYN-ACK, ACK) and connection teardown (FIN/FIN-ACK sequence) are tested both conceptually and as sequence-number calculation problems. Know the state transitions (CLOSED → SYN_SENT → ESTABLISHED → FIN_WAIT → TIME_WAIT → CLOSED).
What is the GATE pass rate for Nigerian candidates?
Pass rates for GATE candidates in Nigeria are published periodically by the awarding body. Practice questions, full-length simulations, and weak-area drills are the highest-impact way to improve your odds.
How long should Nigerian candidates study Computer Networks for the GATE?
For most candidates, focused mastery of Computer Networks requires 20–40 hours of deliberate practice — drilling sample questions, reviewing failure modes, and timing yourself against exam conditions. Nigeria has West Africa's largest exam-prep market. WAEC, JAMB, and NECO are the high-stakes national tests; IELTS and PTE are dominant migration credentials. Combine Computer Networks study with full-length mock exams in the final two weeks before your test date.

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Related study guides

Regulatory citation: GATE 2024 CS Syllabus — Computer Networks (OSI/TCP-IP Layers, LAN Protocols, IP Addressing, Routing, Transport Layer, Application Layer).