Which routing entries supply the RPF check route
Short answer
ABC The RPF check selects the optimal route toward the source from unicast, multicast static, and MBGP routing entries, never from dynamic multicast protocol state.
Question
Key Takeaways
The question tests which tables feed RPF route selection; the trap is assuming PIM's dynamic multicast state counts as a routing source when PIM only consumes the RPF result.
Huawei multicast RPF checks pick the best path back to a source from unicast, multicast static and MBGP routing entries — answer A, B and C — while dynamic multicast protocols like PIM supply no route of their own.
Common mistake: D (multicast dynamic routing entries) — PIM is dynamic and multicast, so it looks like a fourth route source, but PIM never installs routes toward sources; it builds forwarding trees from the RPF result.
Expert Analysis
The trap: option D
Option D, multicast dynamic routing entries, is the most attractive wrong choice because PIM is precisely the dynamic multicast protocol that builds the delivery tree, and the question itself frames RPF as a core multicast function. It satisfies the "multicast" half of the premise and feels like a natural fourth source of routing information. It stops being correct at one point: dynamic multicast protocols such as PIM do not install routes toward a source into any table that the RPF check consults. PIM consumes the result of the RPF lookup to determine the upstream interface, then creates (S,G) or (*,G) forwarding state from it. There is no separate "multicast dynamic routing table" used for RPF route selection.
What the RPF check actually consults
Huawei multicast design draws the best route back to a source from three independent information sources: ordinary unicast routing entries (option A, the default when no special configuration exists), explicitly configured multicast static routing entries (option B), and MBGP-learned entries (option C), which matter when multicast and unicast reachability to the source diverge. Among these candidates the router selects the optimal route and validates the arriving packet's incoming interface against it. A community explanation makes the same point, stating that PIM builds forwarding trees based on the RPF check against the unicast table, multicast static routes or MBGP, rather than creating its own routes toward sources.
Correct set
The correct letters are A, B and C. A multicast static route or an MBGP route may override the default unicast path, but nothing learned dynamically by PIM participates in the selection.
Exam Strategy
On Huawei multicast RPF questions, separate route sources from tree-building protocols: PIM and MSDP construct forwarding state, so any option naming a dynamic multicast protocol as a route table is a distractor. Ask instead which tables can actually return a next hop toward the source — unicast, multicast static, MBGP — and select all of them, since these multi-select items rarely have a single answer.
Frequently Asked Questions
Does PIM participate in the RPF check as a routing source?
Which table is used for RPF when no multicast static or MBGP route exists?
Why do MBGP routes matter for an RPF check?
Community Votes
34% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 1 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 1
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HCIP Resolutor 👍 1Protocolos de enrutamiento dinámico multicast como PIM no crean sus propias rutas hacia las fuentes, sino que construyen los árboles de reenvío basándose en la verificación RPF contra la tabla de enrutamiento Unicast, Rutas Estáticas Multicast o MBGP. Las tres fuentes reales de información de rutas que un router consulta de forma independiente para seleccionar la ruta RPF óptima hacia la fuente son: Unicast routing table (A), Multicast static routing table (B) y MBGP routing table (C). Por lo tanto, las respuestas correctas son A, B y C.
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