What is the difference between PIM-SM protocol and PIM-DM protocol? (Multiple choice) A. BSR/RP only exists in PIM-SM network and does not exist in PIM-DM B. PIM-DM periodically floods the network…

Question

Options

• ABSR/RP only exists in PIM-SM network and does not exist in PIM-DM
• BPIM-DM periodically floods the network without receiving traffic from the network, while PIM-DM floods periodically and there is no redundant traffic in the network.
• CPIM-DM assumes a small number of receivers in the network while PIM-DM assumes a large number of receivers in the network
• DRPT and SPT trees exist in PIM-SM, while only SPT trees exist in PIM-DM

• A
  76% (25)
• B
  24% (8)

Explanation

Options A, C, and D are correct because they accurately capture the core architectural differences between the two protocols.

A is correct because BSR (Bootstrap Router) and RP (Rendezvous Point) are fundamental to PIM-SM's shared-tree model - receivers register with the RP to receive traffic. PIM-DM has no need for these roles since it uses a simple flood-and-prune mechanism without a central rendezvous point.

C is correct (note the typo in the question - both say "PIM-DM", but the intended reading is PIM-SM vs PIM-DM): PIM-SM (Sparse Mode) is designed for networks where receivers are few and spread out, while PIM-DM (Dense Mode) assumes receivers are plentiful and densely distributed, justifying its flood-first approach.

D is correct because PIM-SM builds two tree types - an RPT (shared tree rooted at the RP) for initial delivery, then optionally switches to an SPT (Shortest Path Tree) for efficiency - whereas PIM-DM only ever builds SPTs since it floods outward from the source directly.

B is wrong because it contradicts itself (it says "PIM-DM" twice) and gets the facts backwards: PIM-DM does generate redundant traffic through periodic flooding before pruning dead branches, while PIM-SM avoids redundant traffic by only forwarding where receivers exist.

Memory tip: Think of the letters - Sparse Mode = Selective (needs RP, uses RPT+SPT, few receivers); Dense Mode = Dump traffic everywhere first, then prune (no RP, SPT only, many receivers assumed).

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