Network Layer Performance MCQs

1. Which factor affects the performance of the network layer the most?

a) Bandwidth b) Propagation delay c) Processing time d) All of the above

Correct Answer: d) All of the above

Explanation:
Network layer performance is influenced by multiple factors: bandwidth (data capacity), propagation delay (time for signals to travel), and processing time (router/switch processing). All these factors collectively determine the overall network performance.

2. The time taken for a packet to travel from source to destination is called:

a) Throughput b) Latency c) Bandwidth d) Jitter

Correct Answer: b) Latency

Explanation:
Latency (or delay) measures the time taken for a packet to travel from source to destination. Throughput measures data transfer rate, bandwidth is capacity, and jitter is variation in delay.

3. Which metric is used to measure the number of packets successfully delivered per unit time?

a) Latency b) Jitter c) Throughput d) Propagation delay

Correct Answer: c) Throughput

Explanation:
Throughput measures the actual data transfer rate - the amount of data successfully delivered per unit time. It's a key indicator of network performance and efficiency.

4. Which of the following factors can cause delay in network layer performance?

a) Queuing delay b) Transmission delay c) Propagation delay d) All of the above

Correct Answer: d) All of the above

Explanation:
Network delays consist of: queuing delay (time in router buffers), transmission delay (time to push bits onto the link), and propagation delay (time for signals to travel through the medium). All contribute to total latency.

5. What is the effect of congestion at the network layer?

a) Increased packet loss b) Decreased transmission speed c) Increased delay d) All of the above

Correct Answer: d) All of the above

Explanation:
Network congestion leads to: packet loss (full buffers drop packets), reduced throughput (slower transmission), and increased delay (longer queuing times). These effects degrade overall network performance.

6. If the bandwidth of a network link is 10 Mbps, how many bits can be transmitted in 1 second?

a) 10,000 bits b) 1,000,000 bits c) 10,000,000 bits d) 100,000,000 bits

Correct Answer: c) 10,000,000 bits

Explanation:
10 Mbps = 10 Megabits per second = 10,000,000 bits per second (1 Megabit = 1,000,000 bits). This is the theoretical maximum capacity of the link.

7. What is the difference between latency and throughput?

a) Latency measures delay, throughput measures data transfer rate b) Throughput measures delay, latency measures data transfer rate c) Latency and throughput are the same d) Latency is always greater than throughput

Correct Answer: a) Latency measures delay, throughput measures data transfer rate

Explanation:
Latency (measured in milliseconds) is the time delay in packet delivery. Throughput (measured in bits per second) is the actual data transfer rate. They are different but related performance metrics.

8. Which of the following is a method used to improve network layer performance?

a) Load balancing b) Packet prioritization c) Traffic shaping d) All of the above

Correct Answer: d) All of the above

Explanation:
Performance optimization techniques include: load balancing (distributing traffic across paths), packet prioritization (QoS for important traffic), and traffic shaping (controlling data flow rates).

9. What is the primary goal of Quality of Service (QoS) in network performance?

a) Increase network latency b) Provide fair bandwidth distribution c) Reduce congestion by dropping packets d) Increase jitter

Correct Answer: b) Provide fair bandwidth distribution

Explanation:
QoS aims to manage network resources by prioritizing certain types of traffic and ensuring fair bandwidth allocation. It actually reduces latency and jitter while managing congestion intelligently.

10. What is jitter in network performance?

a) The time taken to deliver the first packet b) Variation in delay between packets c) The amount of data transferred per second d) Packet loss due to congestion

Correct Answer: b) Variation in delay between packets

Explanation:
Jitter measures the variability in packet arrival times. Consistent latency means low jitter, while varying delays cause high jitter - particularly problematic for real-time applications like VoIP.

11. A network with high throughput but high latency is:

a) Ideal for real-time applications b) Good for large file transfers c) Best suited for VoIP calls d) Inefficient for any application

Correct Answer: b) Good for large file transfers

Explanation:
High throughput (large data capacity) with high latency (delay) is acceptable for bulk data transfers where completion time matters more than immediate delivery. Real-time apps need low latency.

12. Which of the following can improve the efficiency of packet forwarding at the network layer?

a) Faster routers b) Larger buffers c) Better congestion control mechanisms d) All of the above

Correct Answer: d) All of the above

Explanation:
Packet forwarding efficiency can be improved by: faster router hardware (a), adequate buffering (b), and intelligent congestion control (c) to manage traffic flows and prevent bottlenecks.

13. The time taken by a packet to travel from the source to the destination, including all delays, is called:

a) Jitter b) Propagation delay c) End-to-end delay d) Queuing delay

Correct Answer: c) End-to-end delay

Explanation:
End-to-end delay is the total time a packet takes to traverse the network from source to destination, including all types of delays: transmission, propagation, processing, and queuing delays. Jitter is variation in this delay, while propagation and queuing delays are components of the total delay.

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