An engineer with an employee ID: 4535:15:507 must implement PIM-SSM in the network to support a new multicast messaging service. All the routers in the network run a distance vector routing…

Question

Options

• AIGMPv3 on all interfaces that participate in multicast
• BPIM RP feature on the network
• CPIM dense mode on all devices on the network
• DPIM dense mode and IGMPv2 on all interfaces that participate in multicast

• A
  83% (30)
• B
  3% (1)
• C
  8% (3)
• D
  6% (2)

Explanation

IGMPv3 is required because PIM-SSM operates on source-specific multicast groups (S,G), and only IGMPv3 gives hosts the ability to specify which source they want traffic from - earlier versions (v1/v2) only support (*,G) any-source joins. Without IGMPv3 on participating interfaces, hosts cannot signal the source-specific membership reports that SSM depends on. The note about unicast routing being established is the satisfied prerequisite - PIM ("Protocol Independent") already leverages that, so the remaining gap is host-to-router signaling via IGMPv3.

Why the distractors are wrong:

• B - PIM-SSM explicitly eliminates the need for a Rendezvous Point (RP). RP is a PIM-SM (Sparse Mode) concept; SSM builds source trees directly.
• C - PIM Dense Mode uses flood-and-prune and is architecturally incompatible with SSM; enabling it would not implement PIM-SSM.
• D - Combines two wrong answers: Dense Mode doesn't apply, and IGMPv2 lacks source-filtering capability, making it insufficient for SSM operation.

Memory tip: Link the "S" in SSM to the "S" in IGMPv3's Source-filtering feature - "SSM needs the Source-aware version of IGMP, which is v3." If you remember that SSM = source-specific and IGMPv3 = source-filtering, the answer is immediate.

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