This is the MCQs in Congestion Control and Quality of Service from book the Data Communications and Networking 4th Edition by Behrouz A. Forouzan. If you are looking for a reviewer in Electronics Systems and Technologies (Communications Engineering) this will definitely help you before taking the Board Exam.
Topic Outline
- DATA TRAFFIC
- CONGESTION
- Open-Loop Congestion Control
- Closed-Loop Congestion Control
- TWO EXAMPLES
- Congestion Control in TCP
- Congestion Control in Frame Relay
- QUALITY OF SERVICE
- TECHNIQUES TO IMPROVE QoS
- INTEGRATED SERVICES
- DIFFERENTIATED SERVICES
- QoS IN SWITCHED NETWORKS
- QoS in Frame Relay
- QoS in ATM
Begin and Good luck!
Choose the letter of the best answer in each questions.
1. _______ is a flow characteristic that applications can tolerate in different degrees.
- A) Reliability
- B) Delay
- C) Jitter
- D) Bandwidth
2. The _______ defines the maximum data rate of the traffic.
- A) peak data rate
- B) maximum burst size
- C) effective bandwidth
- D) none of the above
3. In Frame Relay, the _____________ defines an average rate in bits per second.
- A) access rate
- B) committed burst size
- C) committed information rate
- D) excess burst size
4. In ________ congestion control, policies are applied to prevent congestion before it happens.
- A) open-loop
- B) closed-loop
- C) either (a) or (b)
- D) neither (a) nor (b)
5. In ________ we try to avoid traffic congestion.
- A) congestion control
- B) quality of service
- C) either (a) or (b)
- D) both (a) and (b)
6. _________ is a characteristic that a flow needs. Lack of it means losing a packet or acknowledgment, which entails retransmission.
- A) Reliability
- B) Delay
- C) Jitter
- D) Bandwidth
7. In a network, after the load reaches the capacity, throughput _______.
- A) increases sharply
- B) increases proportionally with the load
- C) declines sharply
- D) declines proportionally with the load
8. In _________ queuing, the packets are assigned to different classes and admitted to different queues. The queues, however, are weighted based on the priority of the queues; higher priority means a higher weight. The system processes packets in each queue in a round-robin fashion with the number of packets selected from each queue based on the corresponding weight.
- A) FIFO
- B) priority
- C) weighted fair
- D) none of the above
9. In ATM, the _________ class is a best-effort delivery service that does not guarantee anything.
- A) CBR
- B) VBR
- C) ABR
- D) UBR
10. The________ normally refers to the maximum length of time the traffic is generated at the peak rate.
- A) peak data rate
- B) maximum burst size
- C) effective bandwidth
- D) none of the above
11. In _______ congestion control, mechanisms are used to alleviate congestion after it happens.
- A) open-loop
- B) closed-loop
- C) either (a) or (b)
- D) neither (a) nor (b)
12. _______ happens in any system that involves waiting.
- A) Congestion
- B) Jamming
- C) Error
- D) none of the above
13. In the ________ algorithm of TCP, the size of the congestion window increases exponentially until it reaches a threshold.
- A) slow-start
- B) congestion avoidance
- C) congestion detection
- D) none of the above
14. In Frame Relay, the user can never exceed the_________.
- A) access rate
- B) committed burst size
- C) committed information rate
- D) excess burst size
15. In the ___________ algorithm of TCP, the size of the threshold is dropped to one-half, a multiplicative decrease.
- A) slow-start
- B) congestion avoidance
- C) congestion detection
- D) none of the above
16. In _________, when a source makes a reservation, it needs to define a flow specification.
- A) Integrated Services
- B) Differentiated Services
- C) Connectionless
- D) Connection-Oriented
17. A _________ traffic model has a data rate that does not change.
- A) constant bit rate
- B) variable bit rate
- C) bursty
- D) none of the above
18. ________ is the variation in delay for packets belonging to the same flow.
- A) Reliability
- B) Delay
- C) Jitter
- D) Bandwidth
19. A ___________ is a packet sent by a node to the source to inform it of congestion.
- A) backpressure
- B) choke packet
- C) implicit signaling
- D) explicit signaling
20. In ATM, the _________ class delivers cells at a minimum rate. If more network capacity is available, this minimum rate can be exceeded.
- A) CBR
- B) VBR
- C) ABR
- D) UBR
21. In the ________ traffic model, the rate of the data flow changes in time, with the changes smooth instead of sudden and sharp.
- A) constant bit rate
- B) variable bit rate
- C) bursty
- D) none of the above
22. In __________, there is no communication between the congested node or nodes and the source. The source guesses that there is a congestion somewhere in the network from other symptoms.
- A) backpressure
- B) choke packet
- C) implicit signaling
- D) explicit signaling
23. In a network, when the load reaches the network capacity, the delay _______.
- A) increases sharply
- B) decreases sharply
- C) remains constant
- D) cannot be predicted
24. The technique of ________refers to a congestion control mechanism in which a congested node stops receiving data from the immediate upstream node or nodes.
- A) backpressure
- B) choke packet
- C) implicit signaling
- D) explicit signaling
25. In ________ queuing, packets are first assigned to a priority class. Each class has its own queue.
- A) FIFO
- B) priority
- C) weighted fair
- D) none of the above
26. In ________, queuing packets wait in a buffer (queue) until the node (router or switch) is ready to process them.
- A) FIFO
- B) priority
- C) weighted fair
- D) none of the above
27. Traditionally, ________types of characteristics are attributed to a flow.
- A) two
- B) three
- C) four
- D) five
28. In Frame Relay, the ___________ is the maximum number of bits in excess of Bc that a user can send during a predefined time.
- A) access rate
- B) committed burst size
- C) committed information rate
- D) excess burst size
29. In a network, when the load is below the capacity of the network, the throughput ______________.
- A) increases sharply
- B) increases proportionally with the load
- C) declines sharply
- D) declines proportionally with the load
30. In the __________ method, the signal is included in the packets that carry data.
- A) backpressure
- B) choke packet
- C) implicit signaling
- D) explicit signaling
31. In a network, when the load is much less than the capacity of the network, the delay is _________.
- A) at a maximum
- B) at a minimum
- C) constant
- D) none of the above
32. Congestion in a network or internetwork occurs because routers and switches have _______.
- A) tables
- B) queues
- C) crosspoints
- D) none of the above
33. In _________, we try to create an appropriate environment for the traffic.
- A) congestion control
- B) quality of service
- C) either (a) or (b)
- D) both (a) and (b)
34. In Frame Relay, the ________ bit warns the sender of congestion in the network.
- A) BECN
- B) FECN
- C) either (a) or (b)
- D) neither (a) nor (b)
35. In Frame Relay, the ________ bit is used to warn the receiver of congestion in the network.
- A) BECN
- B) FECN
- C) either (a) or (b)
- D) neither (a) nor (b)
36. The ________ is a function of three values: average data rate, peak data rate, and maximum burst size.
- A) peak data rate
- B) maximum burst size
- C) effective bandwidth
- D) none of the above
37. In the _________ algorithm of TCP, the size of the congestion window increases additively until congestion is detected.
- A) slow-start
- B) congestion avoidance
- C) congestion detection
- D) none of the above
38. In ATM, the _________ class is divided into two subclasses: real-time (VBR-RT) and non-real-time (VBR-NRT). VBR-RT is designed for those users who need real-time services (such as voice and video transmission) and use compression techniques to create a variable bit rate. VBR-NRT is designed for those users who do not need real-time services but use compression techniques to create a variable bit rate.
- A) CBR
- B) VBR
- C) ABR
- D) UBR
39. Traffic ______ are qualitative values that represent a data flow.
- A) controls
- B) descriptors
- C) values
- D) none of the above
40. _________ is a class-based QoS model designed for IP.
- A) Integrated Services
- B) Differentiated Services
- C) Connectionless
- D) Connection-Oriented
41. In the ______ bucket algorithm, bursty chunks are stored in the bucket and sent out at an average rate.
- A) leaky
- B) token
- C) either (a) or (b)
- D) neither (a) nor (b)
42. The _______ bucket algorithm allows idle hosts to accumulate credit for the future in the form of tokens.
- A) leaky
- B) token
- C) either (a) or (b)
- D) neither (a) nor (b)
43. In ATM, the _________ class is designed for customers who need real-time audio or video services. The service is similar to that provided by a dedicated line such as a T line.
- A) CBR
- B) VBR
- C) ABR
- D) UBR
44. In the ______ traffic model, the data rate changes suddenly in a very short time.
- A) constant bit rate
- B) variable bit rate
- C) bursty
- D) none of the above
45. In Frame Relay, a ___________ is the maximum number of bits in a predefined time that the network is committed to transfer without discarding any frame or setting the DE bit.
- A) access rate
- B) committed burst size
- C) committed information rate
- D) excess burst size
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