NPTEL Computer Networks And Internet Protocol Week 10 Assignment Answers 2025
1. The CSMA/CD protocol, predominantly used in Ethemet, addresses which of the following
challenges?
a) Efficient encoding and decoding of data signals
b) Synchronization of devices in wireless networks
c) Detection and management of data collisions in shared media networks.
d) Guaranteeing data delivery across multiple broadcast domains.
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2. Which MAC technique is most suitable for bursty traffic with sporadic transmissions?
a) Synchronous MAC with reserved slots.
b) Asynchronous MAC with round-robin allocation.
c) Token passing in ring topology.
d) Contention-based asynchronous MAC.
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3. In Go-Back-N ARQ, why must the size of the sender’s window be less than 2m, where m is the
number of bits in the sequence number?
a) To prevent out-of-order frames from being accepted by the receiver
b) To allow cumulative acknowledgments to function correctly
c) To ensure the receiver’s window size can accommodate all pending frames
d) To avoid ambiguities in the sequence numbers during retransmission
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4. What is the minimum frame size for Ethernet (IEEE 802.3), and why is it important?
a) 46 bytes, to prevent collisions from being detected too late
b) 64 bytes, to ensure collision detection within the frame transmission time.
c) 512 bytes, to maximize bandwidth efficiency.
d) 1500 bytes, to support large data payloads.
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5. In a Selective Repeat ARQ system with a 4-bit sequence number and a sender’s window size of 8, what is the minimum size of the receiver’s buffer to prevent loss of out-of-order frames?
a) 4
b) 8
c) 16
d) 1
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6. A wireless CSMA/CA network uses a backoff algorithm with a contention window size that
doubles after each collision. If the initial contention window size is 32, what is the maximum
contention window size after 4 collisions?
a) 256
b) 512
c) 128
d) 1024
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7. In a shared 75 kbps channel, each station transmits a 20-bit frame every 2000 ms. If the network
uses Slotted Aloha, what is the maximum number of stations that can be supported?
a) 7500
b) 2775
c) 7000
d) 5000
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8.
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9. In a round-robin MAC technique, a network has 10 stations, and each station gets a time slot of 2 ms. If a station has a data frame of 2 KB to transmit, and the transmission rate is 1 Mbps, how many rounds will it take for the station to complete its transmission?
a) 4
b) 8
c) 16
d) 20
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10. A network administrator is analyzing a collision on a traditional Ethernet network using CSMA/CD. They observe the following sequence:
(i) A node transmits a frame after sensing the medium is free.
(ii) A collision occurs, detected by voltage fluctuations.
(ili) A jam signal is transmitted, and the node applics a backoff algorithm.
If the backoff limit is reached without successful transmission, what should the node do next?
a) Retry immediately without further sensing.
b) Send another jam signal and continue to backoff indefinitely.
c) Abort the transmission and report a failure.
d) Switch to a synchronous MAC protocol.
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