When IGMP query is configured with SSM Mapping rules, SSM services can only be provided to member hosts running IGMPv2.

Question

Options

• ATRUE
• BFALSE
• C
• D

• A
  17% (5)
• B
  70% (21)
• C
  7% (2)
• D
  7% (2)

Explanation

B is correct because IGMP SSM Mapping is specifically designed to extend SSM services to hosts running either IGMPv1 or IGMPv2 - not IGMPv2 exclusively. When the router receives a standard (*,G) join from an IGMPv1/v2 host, the SSM Mapping feature translates it into an (S,G) SSM channel subscription using configured rules (static or DNS-based), bridging the gap for hosts that lack native SSM support.

A (TRUE) is wrong because it incorrectly restricts SSM Mapping to IGMPv2 only. IGMPv1 hosts also benefit from this feature. Furthermore, IGMPv3 hosts already support SSM natively and don't need SSM Mapping at all - so the statement's scope is wrong in both directions.

Memory tip: Think of SSM Mapping as a translation layer at the router for legacy IGMP hosts (v1 and v2). The "only IGMPv2" phrasing is a trap - whenever you see "only" in a networking question, verify whether the restriction is real or artificially narrow. Here, it excludes IGMPv1 unjustly and ignores that IGMPv3 is the native SSM protocol.

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