Recommended AP-to-AC Discovery Across Layer 3 Networks
Short answer
C Use DHCP (Option 43) so an AP on a different Layer 3 network learns the AC's IP automatically.
Question
Key Takeaways
The question tests which AP-to-AC discovery mechanism survives a Layer 3 boundary, and the trap is picking broadcast, which cannot cross subnets at all.
When an AP and AC sit on different Layer 3 networks, Huawei recommends DHCP-based discovery, using Option 43 to hand the AP the AC's IP address; the answer is C.
Common mistake: B (Broadcast) is the trap: AP discovery broadcasts work only within a single subnet, so they fail once the AP and AC are separated by a Layer 3 boundary.
Expert Analysis
The decisive constraints The question fixes two conditions at once: the AP and the AC are on different Layer 3 networks, and we must choose the method that is recommended — not merely a method that can work. Both qualifiers eliminate candidates. "Different Layer 3 networks" immediately kills B. Broadcast, because broadcast/multicast discovery frames never leave their own subnet; an AP cannot hear an AC's Layer 2 broadcast across a router boundary. B is eliminated by physics, not by preference.
Why the other two fall short A. DNS can deliver an AC address, but it requires extra DNS server records and infrastructure, so it is possible rather than recommended. D. Manually specified on the AP works and is deterministic, yet the word "recommended" argues against per-AP static settings: it does not scale when APs are provisioned in bulk or the AC address changes. The community analysis reaches the same conclusion, calling DNS "possible, but not recommended" and manual configuration "not scalable" in large environments.
The recommended method C. DHCP is the standard cross-subnet discovery path: the AP gets an address, and the DHCP server hands over the AC's IP in Option 43 (Huawei also uses Option 148). It needs no broadcast reachability and no per-AP manual work, so it satisfies both the Layer 3 constraint and the "recommended" wording. Therefore C is the correct answer.
Exam Strategy
Read the topology qualifier first: any question stating "different Layer 3 networks" or "across subnets" should make you discard Layer 2 mechanisms such as broadcast and multicast before you evaluate the rest. Then apply the demand word — "recommended", "most suitable", "scalable" — which usually eliminates workable-but-impractical options like manual per-AP configuration or extra DNS records. Finally, recall that vendor WLAN designs favour DHCP options (Option 43/148) for AC discovery because they combine reachability with zero-touch provisioning.
Frequently Asked Questions
Why can't broadcast discovery work when the AP and AC are on different subnets?
How does the AP learn the AC address through DHCP?
Is manual AC configuration on the AP ever acceptable?
Community Votes
100% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 2 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 2
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Fmoura17 👍 1 Answered CAvaliação das opções A — DNS → ❌ Possível, mas não recomendado Requer configuração adicional de servidor DNS. B — Broadcast → ❌ Inválido Broadcast não atravessa redes Layer 3. C — DHCP → ✅ Recomendado Utiliza a Option 43 para informar o IP do AC automaticamente ao AP. D — Configuração manual → ❌ Não escalável Funciona, mas é inviável em ambientes grandes.
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orxan1492 👍 1 Answered CDHCP Option 43
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