Exam 350-401 topic 1 question 415 discussion

Priority Queuing (PQ)—This type of queuing places traffic into one of four queues. Each queue has a different level of priority, and higher-priority queues must be emptied before packets are emptied from lower-priority queues. This behavior can “starve out” lower- priority traffic. Reference: https://www.ciscopress.com/articles/article.asp?p=352991&seqNum=7#:~:text=Priority%20Queuing%20(PQ)%E2%80%94This%20type%20of%20queuing%20places%20traffic%20into%20one%20of%20four%20queues.%20Each%20queue%20has%20a%20different%20level%20of%20priority%2C%20and%20higher%2Dpriority%20queues%20must%20be%20emptied%20before%20packets%20are%20emptied%20from%20lower%2Dpriority%20queues.%20This%20behavior%20can%20%E2%80%9Cstarve%20out%E2%80%9D%20lower%2D%20priority%20traffic.

"Which . . . uses four static queues?" Correct is A) Weighted Fair Queuing (also CBWFQ) B) maybe. . .if you're customizing the queueing sure, but there is usually a name tied with your queueing method. C) Same As PQ -- only 1, max 2 PQ or LLQ available, not four static queues. D) A PQ only uses ONE queue out of the four, except a few special platforms which have two priority queues (but they are not called static queues). I've never even heard of hardware that would allow all four queues to be "PQ". That would defeat the purpose of a PQ.

D is correct

Keyword is "four" queues: Priority Queuing. The Cisco CG-OS router supports four priority queue settings for QoS, indexes 1 to 4, where 1 is the highest priority and 4 is the lowest.

https://packetlife.net/media/library/19/QoS.pdf

Correctomundo