300-415 Question #377: Real Exam Question with Answer & Explanation

Question

Options

• Apolicy-map shape_GigabitEthernet4.100 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100
• Bpolicy-map shape_GigabitEthernet4.200 class class-default service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.200
• Cpolicy-map shape_GigabitEthernet4.100 class class-default service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 200 service-policy output shape_GigabitEthernet4.100
• Dpolicy-map shape_GigabitEthernet4.200 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100

Explanation

To shape traffic on a specific subinterface for a VLAN, the policy-map applied to the subinterface must be correctly named and explicitly applied to the corresponding subinterface, with the encapsulation dot1Q matching the target VLAN.

Common mistakes.

• B. This option defines a policy-map named shape_GigabitEthernet4.200 but applies it to interface GigabitEthernet4.100, creating a mismatch between the policy name and its application.
• C. This option configures encapsulation dot1Q 200 on interface GigabitEthernet4.100, which does not match the requirement to shape traffic for VLAN 100.
• D. This option defines a policy-map named shape_GigabitEthernet4.200 but applies service-policy output shape_GigabitEthernet4.100, creating a naming mismatch between the defined policy and the applied policy.

Concept tested. IOS XE QoS policy-map application on subinterfaces

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_plcshp/configuration/xe-3s/qos-plcshp-xe-3s-book/qos-plcshp-overview.html

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