mediumMultiple Select
350-401 Practice Question: Which two statements about PIM sparse mode…
Which two statements about PIM sparse mode (PIM-SM) are true? (Choose two.)
⚠ Common exam trap
The trap is assuming that PIM-SM immediately switches to SPT or that only one RP is allowed, but the exam tests the pull model and the RP's role as the shared tree root, while the SPT switchover is conditional and multiple RPs are supported.
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
✓
PIM-SM uses a pull model where receivers explicitly join the multicast group.
Option A is correct because PIM-SM operates on a pull model: receivers must explicitly signal their interest by sending IGMP joins, which trigger PIM (*,G) Join messages toward the RP, rather than relying on flood-and-prune push behavior. Option B is correct because in PIM-SM the rendezvous point (RP) is the root of the shared distribution tree (the RPT, denoted (*,G)), through which all sources initially send their traffic and receivers join. Option C is incorrect because the switch from the shared tree to the shortest path tree (SPT) is not immediate upon the first packet; it occurs when the last-hop router receives traffic and meets the SPT-switchover threshold, or is triggered administratively. Option D is incorrect because PIM-SM does not require every router to be statically configured with the same RP address; RP information can be learned dynamically via bootstrap router (BSR) or Auto-RP mechanisms. Option E is incorrect because PIM-SM can support multiple RPs per multicast group (for load sharing and redundancy) using anycast RP or MSDP, and a single RP can serve multiple groups.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
PIM-SM uses a pull model where receivers explicitly join the multicast group.
Why this is correct
PIM-SM builds distribution trees only when receivers signal interest, so it operates as a pull model: the last-hop router sends explicit PIM joins toward the rendezvous point. This satisfies the stem's requirement that receivers explicitly join the group, unlike dense-mode flood-and-prune push behaviour.
- ✓
In PIM-SM, the rendezvous point (RP) is the root of the shared tree.
Why this is correct
In PIM sparse mode, receivers join the shared distribution tree whose root is the rendezvous point, and sources register with that RP. Traffic initially flows source-to-RP-to-receivers, satisfying the shared-tree root characteristic before any switch to a shortest-path source tree.
- ✗
PIM-SM automatically switches to the shortest path tree (SPT) immediately after the first multicast packet is received.
Why it's wrong here
PIM-SM initially forwards via the shared tree and switches to the SPT only after traffic exceeds the SPT threshold, not on the first packet. It is tempting because SPT switchover does occur automatically, so the mechanism is real, just triggered by the threshold rather than immediately.
- ✗
PIM-SM requires all routers in the domain to be configured with the same RP address.
Why it's wrong here
PIM-SM domains can use anycast-RP or MSDP peering so multiple RPs serve the domain; identical RP addresses are not required on every router. It is tempting because a single statically configured RP address is the simplest baseline design taught for small PIM-SM domains.
- ✗
PIM-SM supports only one RP per multicast group.
Why it's wrong here
PIM-SM supports multiple RPs per group through anycast-RP or MSDP, allowing redundancy and load sharing across candidate RPs. It is tempting because basic PIM-SM configuration maps each group range to one RP, which looks like a protocol limit rather than a design choice.
Go deeper
Related to this question
About these practice questions
This 350-401 question is part of Courseiva's 1,923-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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.