Refer to the exhibit.
Which statement about configuring the switch to manage traffic is true?
A.
The switchport priority extend cos command on interface FastEthernet0/0 prevents traffic to and
from the PC from taking advantage of the high-priority data queue that is assigned to the IP phone.
B.
The switchport priority extend cos command on interface FastEthernet0/0 enables traffic to and
from the PC to use the high priority data queue that is assigned to the IP phone.
C.
When the switch is configured to trust the CoS label of incoming traffic, the trusted boundary
feature is disabled automatically.
D.
The mls qos cos override command on interface FastEthernet0/0 configures the port to trust the
CoS label of traffic to and from the PC.
In some situations, you can prevent a PC connected to the Cisco IP Phone from taking advantage
of a high-priority data queue. You can use the switchport priority extend cos interface configuration
command to configure the telephone through the switch CLI to override the priority of the traffic
received from the PC.
Reference. http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2950/software/release/12-1_22_ea2/configuration/guide/2950scg/swqos.html
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Odd – I think the answer is C.
Answer D is wrong because “override” means don’t trust and override.
According to
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-2_2_e/vlan/command_reference/b_vlan_1522e_2960x_cr/b_vlan_152ex_2960-x_cr_chapter_010.html
the command “switchport priority extend” influences only incoming traffic from the PC, so answers A and B are wrong.
The answer C makes sense. Trust boundary is where you don’t trust any more, so the CoS value is overridden. So if you configure “trust” it is not a boundary.
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