350-401 Question #571: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An engineer attempts to bundle interface Gi0/0 into the port channel, but it does not function as expected. Which action resolves the issue?

Options

• AConfigure channel-group 1 mode active on interface Gi0/0.
• BConfigure no shutdown on interface Gi0/0
• CEnable fast LACP PDUs on interface Gi0/0.
• DSet LACP max-bundle to 2 on interface Port-channeM

Explanation

Explanation

Setting LACP max-bundle to 2 on the Port-Channel interface resolves the issue because LACP has a default max-bundle limit that restricts how many active physical interfaces can participate in the port channel. If the max-bundle value is set to 1 (or lower than needed), any additional interface attempting to join will be placed in a "hot-standby" state rather than becoming an active bundle member, which is exactly what causes Gi0/0 to fail as expected.

Why the distractors are wrong:

• Option A is incorrect because the interface likely already has LACP configured; the problem is a bundle size restriction, not the LACP mode itself.
• Option B is incorrect because a shutdown state would prevent the interface from appearing in the port channel at all, and the exhibit suggests the interface is already up.
• Option C is incorrect because fast LACP PDUs (fast timers) affect how quickly LACP detects link failures, not whether an interface can join a bundle.

Memory Tip

Think of max-bundle as the "guest list capacity" - even if LACP is properly negotiated, the port channel won't let more interfaces in than the max-bundle limit allows. When bundling fails despite correct configuration, always check if the door is big enough for all the interfaces trying to enter.

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