350-401 Question #27: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. SwitchC connects HR and Sales to the Core switch However, business needs require that no traffic from the Finance VLAN traverse this switch. Which command meets this requirement?

Options

• ASwitchC(config)#vtp pruning
• BSwitchC(config)#vtp pruning vlan 110
• CSwitchC(config)#interface port-channel 1
• DSwitchC(config)#interface port-channel 1

Explanation

Explanation

Option D is correct because it uses the switchport trunk allowed vlan remove 110 command (applied under the port-channel interface) to explicitly remove the Finance VLAN (110) from the trunk link on SwitchC, preventing that VLAN's traffic from ever traversing the switch. This is a manual, precise method of controlling which VLANs are permitted on a trunk interface.

Why the distractors are wrong:

• Option A (vtp pruning) enables VTP pruning globally, but this is an automatic, dynamic process controlled by the VTP server - it doesn't guarantee Finance VLAN traffic will never traverse SwitchC, as pruning decisions can change.
• Option B (vtp pruning vlan 110) is not valid syntax; VTP pruning eligibility is configured with vtp pruning or switchport trunk pruning vlan, not this format.
• Option C appears identical to D in the choices shown, suggesting the exhibit includes the full command switchport trunk allowed vlan remove 110 - the key distinction is that manual trunk VLAN removal is more reliable than VTP pruning for strict security requirements.

Memory Tip: Think "Remove = Reliable" - when a business requires traffic to be blocked, use switchport trunk allowed vlan remove [vlan-id] for guaranteed, static control rather than depending on dynamic VTP pruning.

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