cs4024_2025T3_ET_FN.pdf
Computer Networks · End Term · Sep 2025 FN
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Questions and published explanations below are available without starting a test. Some questions may not have a published solution yet.
Question 2 NAT · 2.0 marks
Assume a host in Mumbai wants to send a packet to a server in Delhi, approximately 1510 km
away. If the signal travels at 2 × 10\(^{6}\) m/s, what is the one-way propagation delay in milliseconds?
NOTE: Assume no processing or queuing delay(in ms).
A published solution is not available for this question yet.
Question 3 NAT · 2.0 marks
If the one-way latency between two cities is measured to be 15 ms, the RTT (Round Trip Time)
assuming symmetric paths and no processing delay is:
A published solution is not available for this question yet.
Question 4 NAT · 3.0 marks
A transmitter sends packets of size 2000 bits at a rate of 3 Mbps from node X to node Y. The one-
way delay is observed to vary between 20 ms (no queueing) and 120 ms (maximum queue), with
an average of 60 ms. Assume queuing occurs only at one router along the path and there is no
packet loss. What is the mean number of packets in the queue at the bottleneck link?
A published solution is not available for this question yet.
Question 5 NAT · 3.0 marks
In a circuit-switched network, a source communicates with a destination through 5 intermediate
switches. Each switch takes 3 ms to process a reservation request before forwarding it to the next
node. The propagation delay between each pair of nodes (i.e., source/switch/destination) is 2 ms.
What is the total time (in milliseconds) taken for the reservation request to reach the destination?
A published solution is not available for this question yet.
Question 6 SHORT_TEXT · 3.0 marks
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A published solution is not available for this question yet.
Question 7 NAT · 3.0 marks
A TCP connection uses the following identifiers:
• Source IP = 192.168.1.10
• Destination IP = 10.0.0.5
• Source Port = 55000
• Destination Port = 80
Assuming that TCP port numbers range from 0 to 65535, but 0–1023 are the well-known
(privileged) ports and are excluded, how many additional TCP connections can this host
theoretically open to the same server (IP 10.0.0.5, port 80) using different source ports?
A published solution is not available for this question yet.
Question 8 NAT · 3.0 marks
A 20 Mbps link has a propagation delay of 400 μs. The transmitter employs the Stop-and-Wait
protocol. Assuming each frame is 100 bytes long, what is the maximum data rate possible?
A published solution is not available for this question yet.
Question 9 NAT · 3.0 marks
If you are designing sliding window protocol (assume selective repeat) of 7 Mbps which has one
way delay of 1.55 seconds. Assuming each frame carries 1kB of data, what is the minimum
number of bits you need for the sequence number?
A published solution is not available for this question yet.
Question 10 NAT · 3.0 marks
In a network with a bottleneck bandwidth of 25 Mbps and a round-trip time of 400 ms,what should
be the minimum congestion window size (in bytes) to fully utilize the link?
A published solution is not available for this question yet.
Question 11 NAT · 3.0 marks
A TCP flow has a congestion window of 54 KB and an RTT of 510 ms. Calculate the average
throughput in Mbps. **Note**: In two point precision
A published solution is not available for this question yet.
Question 12 NAT · 3.0 marks
In TCP BBR’s bottleneck bandwidth estimation, the ACK arrival rate measured over an epoch gives
a delivery rate of 48 Mbps. If the minimum measured RTT (RTTmin) is 100 ms, what is BBR’s
current estimate of the bottleneck bandwidth (in Mbps)?
A published solution is not available for this question yet.
Question 13 NAT · 3.0 marks
A TCP Reno connection detects congestion when CWND = 100 KB. After triple duplicate ACK,
CWND is reduced to 3/4, and additive increase resumes with +1 KB per RTT. Compute the CWND
after 3 RTTs post-loss.(in KB)
A published solution is not available for this question yet.
Question 14 NAT · 3.0 marks
An ISP manages a network block of 200.8.0.0/10. it partitions and assigns a customer a smaller
block 200.8.4.128/22. Calculate the number of network bits that were added to the prefix length
during this delegation process and then find how many total subnets could the ISP theoretically
create from the original /10 block if it subdivides it all the way down to /22 subnets?
A published solution is not available for this question yet.
Question 15 NAT · 3.0 marks
How many distinct prefixes can a /10 block be divided into when it is subnetted up to /18
networks?
A published solution is not available for this question yet.
Question 16 NAT · 3.0 marks
An organization has 2,200 devices connected in a private network. Each NAT router can handle up
to 80,000 simultaneous connections and can serve 290 devices comfortably. If they use NAT (one
public IP per NAT router), how many public IP addresses are required?
A published solution is not available for this question yet.
Question 17 MCQ · 1.0 marks
When using Dijkstra’s algorithm to find shortest path in a graph, which of the following statement
is not true?
It can find shortest path within the same graph data structure
Every time a new node is visited, we choose the node with smallest know
distance/cost (weight) to visit first
Shortest path always passes through least number of vertices
The graph needs to have a non-negative weight on every edge
A published solution is not available for this question yet.
Question 18 MCQ · 1.0 marks
The browser connects (TCP handshake visible) but the webpage never loads. What is the MOST
likely issue?
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[[IMAGE:61524c429bd5b208_8_6]]
A published solution is not available for this question yet.
Question 19 MCQ · 1.0 marks
The server prints the GET request in console but the browser keeps “Waiting for localhost...”. Why?
The server didn’t call accept()
The server didn’t send file data back using send()
Browser sent POST instead of GET
TCP packet was dropped
A published solution is not available for this question yet.
Question 20 MCQ · 1.0 marks
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[[IMAGE:61524c429bd5b208_9_9]]
[[IMAGE:61524c429bd5b208_9_10]]
[[IMAGE:61524c429bd5b208_9_11]]
A published solution is not available for this question yet.
Question 21 MCQ · 1.0 marks
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8 bytes
16 bytes
20 bytes
32 bytes
A published solution is not available for this question yet.
Question 22 MCQ · 2.0 marks
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The browser expects an HTTP response, but the server closes the connection
without sending one.
The buffer size is too large, causing a deadlock.
read() cannot be used with HTTP traffic; recv() must be used.
The server must send a TCP FIN before printf.
A published solution is not available for this question yet.