1. What is the primary goal of congestion control in networks?
Correct Answer: b) Prevent network overload and ensure smooth data flow
Explanation: Congestion control aims to prevent network resources from being overwhelmed while maintaining efficient data transfer rates.
2. Which of the following is a symptom of network congestion?
Correct Answer: a) Increased packet loss
Explanation: Network congestion typically manifests through increased packet loss, higher latency, and reduced throughput.
3. Congestion control is mainly implemented in which layer of the OSI model?
Correct Answer: d) Transport Layer (but also handled at Network Layer in some cases)
Explanation: While primarily a Transport Layer function (e.g., in TCP), some congestion control mechanisms also exist at the Network Layer (e.g., in routers).
4. What is the difference between congestion control and flow control?
Correct Answer: a) Congestion control prevents network overload, while flow control prevents receiver overload
Explanation: Flow control manages the sender-receiver speed mismatch, while congestion control manages overall network traffic to prevent congestion collapse.
5. Which of the following is an open-loop congestion control technique?
Correct Answer: b) Leaky Bucket Algorithm
Explanation: Open-loop techniques like Leaky Bucket control congestion without network feedback, while closed-loop techniques (like TCP's) use feedback.
6. The Leaky Bucket algorithm is used for:
Correct Answer: b) Traffic shaping and congestion control
Explanation: The Leaky Bucket algorithm smooths out bursty traffic by regulating the output rate, making it useful for traffic shaping and congestion control.
7. In the Leaky Bucket algorithm, if the bucket size is 1000 bytes and the output rate is 100 bytes/sec, how long will it take to empty a full bucket?
Correct Answer: b) 10 sec
Explanation: Time = Bucket size / Output rate = 1000 bytes / 100 bytes/sec = 10 seconds.
8. What is a key disadvantage of the Leaky Bucket algorithm?
Correct Answer: a) It does not handle bursty traffic well
Explanation: The Leaky Bucket's strict output rate smoothing can be inefficient for applications that benefit from occasional bursts of traffic.
9. Which parameter controls the rate of outgoing traffic in the Leaky Bucket algorithm?
Correct Answer: b) Leak rate
Explanation: The leak rate determines how quickly packets leave the bucket (the output rate), regardless of input burstiness.
10. The Leaky Bucket algorithm is an example of:
Correct Answer: a) Open-loop congestion control
Explanation: It's open-loop because it regulates traffic without feedback about current network conditions.
11. How does the Token Bucket algorithm differ from the Leaky Bucket algorithm?
Correct Answer: a) Token Bucket allows bursty traffic, while Leaky Bucket does not
Explanation: Token Bucket allows bursts up to bucket capacity, while Leaky Bucket strictly enforces the output rate.
12. In the Token Bucket algorithm, tokens are generated at a fixed rate. If the rate is 10 tokens/sec and the bucket size is 50 tokens, how many tokens are available after 7 seconds if the bucket was initially empty?
Correct Answer: a) 50
Explanation: Tokens generated = 10 tokens/sec × 7 sec = 70 tokens, but limited by bucket capacity of 50 tokens.
13. Which algorithm is better for real-time traffic like video streaming?
Correct Answer: b) Token Bucket
Explanation: Token Bucket's ability to handle bursts makes it more suitable for real-time applications that occasionally need to send data quickly.
14. What happens if a packet arrives when no tokens are available in the Token Bucket?
Correct Answer: a) The packet is discarded
Explanation: When no tokens are available, packets are typically dropped (though some implementations may buffer them). This enforces strict rate limiting.
15. The Token Bucket algorithm is used in:
Correct Answer: b) QoS (Quality of Service) policies
Explanation: The Token Bucket algorithm is commonly implemented in network devices to enforce QoS policies and traffic shaping rules.