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Exam 300-420 All Questions

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Exam 300-420 topic 1 question 231 discussion

Actual exam question from Cisco's 300-420
Question #: 231
Topic #: 1
[All 300-420 Questions]

In a multicast network, which condition must be met for an RPF check to be performed on the RP address?

  • A. The PIM router or multilayer switch has a source-tree state.
  • B. The PIM DM device receives a multicast packet and has no directly connected members.
  • C. The PIM DM device receives a multicast packet and has no directly connected PIM neighbor.
  • D. The PIM router or multilayer switch has a shared-tree state.
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Suggested Answer: D 🗳️

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nicolamazzoletti
7 months, 1 week ago
Selected Answer: D
RPF is performed against FHR when in SPT/Source tree state and against RP when in Shared tree state
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Lungful
8 months, 1 week ago
Selected Answer: D
D is correct. "If a PIM router has no source-tree state, it is considered a shared tree state. The router will perform a RPF check on the address of the rendezvous point – the rendezvous address is known when members join the group" https://www.routeprotocol.com/reverse-path-forwarding-rpf/
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dgonzalezexamtopics
9 months, 4 weeks ago
But RPF is not used with PIM-DM? Then it wouldn't be any RP neither shared-trees, but sources one. Would it is so?
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SpicyMochi
12 months ago
Selected Answer: D
D. The PIM router or multilayer switch has a shared-tree state. In a multicast network, the Reverse Path Forwarding (RPF) check is performed to ensure that multicast traffic flows along the optimal path and to prevent loops. When a PIM router or multilayer switch has a shared-tree state, it means that it is using a shared distribution tree with a Rendezvous Point (RP) at its root. In this case, the RPF check is performed on the RP address to ensure that multicast packets are being received from the correct upstream path toward the RP.
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