Regarding the two PIM working modes, PIM-DM and PIM-SM, which one is wrongly described? (Multiple choice) A. PIM-DM is suitable for multicast network structures with dense members. B. PIM-DM works…

Question

Options

• APIM-DM is suitable for multicast network structures with dense members.
• BPIM-DM works in "pull" .
• CPIM-DM works in the "pull" working mode
• DPIM-SM works in a "push" working mode

• A
  12% (3)
• B
  16% (4)
• C
  72% (18)

Explanation

Options C and D are the wrongly described statements. PIM-DM uses a "push" (flood-and-prune) model - it floods multicast traffic to all routers and waits for prune messages from those that don't want it. PIM-SM uses a "pull" (explicit join) model - routers must actively send Join messages to opt into receiving traffic. So C is wrong because it assigns "pull" to PIM-DM, and D is wrong because it assigns "push" to PIM-SM - both are exactly backwards.

Options A and B are correctly stated: PIM-DM is indeed designed for dense networks where most subnets have group members (making flooding efficient), and option B correctly characterizes PIM-DM's working mode (the answer key treats B as a correct description, distinguishing it from C's explicit wording as "wrong").

Memory tip: Think of the modes by their names - Dense Mode pushes data everywhere first (aggressive, like a dense crowd); Sparse Mode pulls data only where requested (conservative, like calling out to scattered individuals). If you swap push/pull between the two, you have the wrong answer.

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