Why Exclude an End User's PC Device from a QoS Trust Boundary?

B.

A QoS (Quality of Service) trust boundary is used to identify the devices or network segments whose traffic can be trusted to have the appropriate QoS markings. Devices within the trust boundary are given preferential treatment for traffic prioritization over devices outside of it.

In the context of an end user's PC device, it is not recommended to include it in the QoS trust boundary. The reason for this is that end users may incorrectly tag their traffic to bypass firewalls or prioritize their traffic over other network traffic.

Option A: The end user could incorrectly tag their traffic to bypass firewalls. This is a valid concern, as end users may try to bypass firewall policies by tagging their traffic with a high QoS marking to ensure it is not dropped by the firewall. This can create security vulnerabilities that can be exploited by attackers.

Option B: The end user may incorrectly tag their traffic to be prioritized over other network traffic. This is also a valid concern, as end users may try to prioritize their traffic over other traffic on the network, potentially causing congestion and affecting the QoS of other applications.

Option C: There is no reason not to include an end user's PC device in a QoS trust boundary. This is an incorrect option, as there are valid reasons not to include an end user's PC device in a QoS trust boundary, as mentioned above.

Option D: The end user could incorrectly tag their traffic to advertise their PC as a default gateway. This is another potential issue, as end users may try to advertise their PC as a default gateway, which could disrupt network operations and cause routing issues.

In summary, end user's PC devices should not be included in a QoS trust boundary due to the potential risks of incorrect QoS tagging and security vulnerabilities.