hardMultiple SelectObjective-mapped
350-401 Practice Question: Which three statements about RPF check in IP…
Which three statements about RPF check in IP multicast are true? (Choose three.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The RPF check ensures that multicast packets are forwarded only if they arrive on the interface that the router would use to send unicast traffic back to the source.
The RPF check is a fundamental multicast forwarding mechanism that verifies the source address of incoming multicast packets against the unicast routing table. A packet passes RPF if it arrives on the interface that the router would use to reach the source. If the RPF check fails, the packet is dropped to prevent loops. RPF is performed on every multicast packet, not just the first one. The RPF check is independent of the multicast routing protocol; it uses the unicast routing table. RPF failure can occur even with a correct unicast route if the packet arrives on a different interface.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The RPF check ensures that multicast packets are forwarded only if they arrive on the interface that the router would use to send unicast traffic back to the source.
Why this is correct
Correct because the RPF check uses the unicast routing table to determine the expected incoming interface for the source.
- ✓
If the RPF check fails, the multicast packet is dropped by the router.
Why this is correct
Correct because a failed RPF check indicates a potential routing loop, so the packet is discarded.
- ✗
The RPF check is performed only on the first packet of a multicast stream to determine the forwarding path.
Why it's wrong here
Incorrect because the RPF check is performed on every incoming multicast packet to maintain loop-free forwarding.
- ✗
The RPF check relies solely on the multicast routing table (MRIB) to determine the incoming interface.
Why it's wrong here
Incorrect because the RPF check uses the unicast routing table (RIB), not the multicast routing table (MRIB).
- ✓
A multicast packet can fail the RPF check even if the unicast route to the source exists, if the packet arrives on a different interface than the one used for unicast return traffic.
Why this is correct
Correct because the RPF check compares the arrival interface with the unicast route's outgoing interface; a mismatch causes failure.
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
About these practice questions
One of 1,175 original 350-401 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.