350-401 Question #156: Real Exam Question with Answer & Explanation

Question

Why is an AP joining a different WLC than the one specified through option 43?

Options

• AThe WLC is running a different software version.
• BThe API is joining a primed WLC
• CThe AP multicast traffic unable to reach the WLC through Layer 3.
• DThe APs broadcast traffic is unable to reach the WLC through Layer 2.

Explanation

AP Joining a Different WLC Than Option 43 Specifies

Option B is correct because a primed WLC takes priority over DHCP Option 43 in the WLC discovery process. When an AP has been previously configured ("primed") to join a specific WLC, that stored controller information is checked before Option 43 in the AP's discovery algorithm, causing it to join the primed WLC instead.

Why the distractors are wrong:

• A is incorrect because a software version mismatch would prevent the AP from joining at all (or trigger an automatic upgrade), not redirect it to a different WLC.
• C is incorrect because multicast is used for WLC discovery, not the joining process itself, and a failure would prevent joining entirely rather than redirect to another WLC.
• D is incorrect because Layer 2 broadcast issues would similarly block discovery altogether, not cause redirection to a different controller.

🧠 Memory Tip: Think of "primed" as a pre-programmed preference - like a GPS that remembers your home address regardless of new directions given. The AP's internal memory always wins over DHCP instructions because it's checked first in the discovery order: Prior knowledge > DHCP > DNS > Broadcast.

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