Implementing and Operating Cisco Collaboration Core Technologies (CLCOR) — Question 364

If a trust boundary is placed on a Cisco IP phone, what occurs with the packets that come to the phone from a PC?

Answer options

• A. The phone sets/resets the CoS field to 3 for voice signaling and 5 for voice traffic.
• B. The phone does not mark any packets, and the access switch sets up the CoS values.
• C. The phone sets/resets the CoS field to 0; voice signaling is set to 3; and voice traffic is set to 5.
• D. QoS is performed at the distribution layer, and packets are marked at this boundary.

Correct answer: C

Explanation

The correct answer is C because when a trust boundary is applied, the Cisco IP phone can set the CoS field values for voice signaling and voice traffic accordingly. Options A and B are incorrect as they either misrepresent the marking process or indicate that the phone does not modify packets at all. Option D is also incorrect, as it suggests that QoS marking occurs at a different level rather than at the phone itself.