Exam 300-430 topic 1 question 18 discussion

The Correct Answer is D. "When you enter the mls qos trust cos command on a port, the switch uses the CoS marking on incoming packets in order to put the packet in the right queue. When the packet is resent, the switch makes the DSCP value correspond to the CoS." See: https://www.cisco.com/c/en/us/support/docs/wireless-mobility/voice-over-wireless-lan-vowlan/116056-technote-qos-00.html#anc3

Answer is C. https://www.cisco.com/c/en/us/support/docs/wireless-mobility/voice-over-wireless-lan-vowlan/116056-technote-qos-00.html#:~:text=When%20you%20enter,to%20the%20CoS. "Set to match" vs "correspond to"

In a wireless QoS deployment, voice traffic needs to be prioritized throughout the network. The Class of Service (CoS) values are assigned based on 802.1p (Layer 2 QoS), while Differentiated Services Code Point (DSCP) values are used for Layer 3 QoS. ✔ mls qos trust cos ensures that the switch trusts the CoS value assigned by the WLC and maps it to the appropriate DSCP value for end-to-end QoS.

Concentrate on the wording. DSCP to correspond to CoS. Answer is D.

The engineer wants to use the wireless voice traffic class of service to determine the queue order for packets received. This means that Quality of Service (QoS) needs to be configured to prioritize voice traffic. “cos” stands for Class of Service, which is typically used for Ethernet frames and not specifically designed for voice traffic prioritization. In this case, the engineer wants to prioritize voice traffic using the wireless voice traffic class of service, which is better achieved by trusting the Differentiated Services Code Point (DSCP) value rather than the Class of Service (COS) value. Therefore, option D is not the right configuration, and option C, “msl qos trust dscp configured on the controller switch port,” is the correct configuration required in the network.

D is correct - trust cos

Ignore the reference to DSCP upon resend. It is meant to throw you off and is irrelevant to what the question is asking. The key ask here is to use the CoS to determine queue order for frames received on a switch.

Answer D. I agree with andit explanation.

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/voice-over-wireless-lan-vowlan/116056-technote-qos-00.html#:~:text=When%20you%20enter,to%20the%20CoS.

not msl qos.. but mls qos

If WLAN QoS is default, the voice class of service will be rewritten to default on the controller. Platinum QoS must be enabled to maintain class of service for received voice packets.

Correct answer is D because the engineer was the voice traffic CLASS OF SERVICE to be used. So we're wanting to trust COS and have the switch then remark DSCP to match.

C dscp

Provided answer is correct

Correct answer is D

answer is D

I think is A, because that commands are globally enable, not per port. And the answer talk about mark the traffic on the wireless, so the need to implement QoS on the wireless.