Which statement about multicast RPs is true?

Question

Options

• ARPs are required only when using protocol independent multicast dense mode.
• BRPs are required for protocol independent multicast sparse mode and dense mode.
• CBy default, the RP is needed periodically to maintain sessions with sources and receivers
• DBy default, the RP is needed only to start new sessions with sources and receivers.

• B
  5% (1)
• C
  5% (1)
• D
  91% (20)

Explanation

Multicast Rendezvous Points (RPs) Explained

Option D is correct because in PIM Sparse Mode, the Rendezvous Point (RP) acts as a meeting point only during session initiation - once the source and receiver are discovered, the network builds a Shortest Path Tree (SPT) directly between them, and traffic flows without ongoing RP involvement.

Why the distractors are wrong:

• A is wrong because RPs are used in Sparse Mode, not Dense Mode. Dense Mode floods traffic and uses pruning - it doesn't need an RP at all.
• B is wrong because Dense Mode operates without an RP; it relies on flood-and-prune behavior rather than a central registration point.
• C is wrong because it describes the opposite of default behavior. The RP is not required to maintain ongoing sessions - after the SPT switchover occurs, the RP is bypassed for data forwarding.

Memory Tip: Think of the RP as a matchmaker - it introduces sources to receivers, but once they're "matched," the conversation continues directly without the matchmaker's involvement. "Sparse = Start only, then bypass the RP!"

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