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- CCNA Routing and Switching 200-125
66.
When should QoS shaping be implemented?
- A.When maintaining a contracted burst rate
- B.When LAN applications require a minimum bit rate
- C.When WAN applications require a minimum bit rate
- D.When the service provider is policing traffic
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| QoS shaping should be used when the service provider is policing traffic. If the traffic is policed and exceeds the CIR, the ISP will drop packets. Therefore, traffic shaping can delay the packets to slow the protocols vs. being dropped by the ISP. |
67.
Which statement is correct about tail drop with QoS queues?
- A.Tail drop is a method of QoS.
- B.Tail drop happens when the queues round-robin.
- C.Tail drop happens when the queues are full.
- D.Tail drop helps slow down protocols that are monopolizing bandwidth.
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| Tail drop happens when the QoS queues are full and cannot send packets fast enough. There is no more room in the queue, and any packets being added to the tail of the queue are dropped. |
68.
When should QoS policing be implemented?
- A.To help police LAN applications
- B.To maintain a contracted CIR
- C.To help police WAN applications
- D.o maintain a contracted burst rate
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| QoS policing should be implemented to adhere network traffic to a contracted CIR. As an example, if your enterprise contracted a Metro Ethernet connection with an access link of 1 Gb/s and a CIR of 400 Mb/s, you would need to make sure that traffic does not exceed the CIR except for occasional bursts. |
69.
Which statement is correct about policing of traffic for QoS?
- A.Policing holds packets in the queue over the configured bit rate to cause delay.
- B.Policing drops packets over the configured bit rate to cause loss.
- C.Policing drops packets over the configured bit rate to cause loss.
- D.Policing slows packets in the queue over the configured bit rate to adhere to the bit rate.
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| Policing monitors the bit rate of packets. If the bit rate is exceeded for a configured queue, then policing drops packets over the configured bit rate, causing loss. In some cases it can be configured to re-mark the packets. |
70.
Which of the following topology terms most closely describe the topology created
by a Metro Ethernet Tree (E-Tree) service? (Choose two answers.)
- A.Which QoS method uses a round-robin scheduler for packet queuing?
- B.FIFO
- C.CBWFQ
- D.PQ
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| Class-Based Weighted Fair Queuing, or CBWFQ, is driven by a round-robin scheduler. The queues are weighted for priority in the scheduler and the packets are put into the queues upon classification. |
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