As shown in the figure, it is a multicast network. Which of the following ports are multicast group member ports? (Multiple choice)

Question

Options

• AIF4
• BIF3
• CIF1
• DIF2

• A
  82% (18)
• B
  5% (1)
• D
  14% (3)

Explanation

In IGMP snooping, multicast group member ports are switch ports that have received IGMP Membership Report (Join) messages from downstream hosts - meaning a host on that port explicitly joined a multicast group. IF1 (C) and IF4 (A) are member ports because hosts connected to them sent IGMP Join messages, signaling active group membership.

IF2 (D) is a router port (the upstream port toward the multicast router), not a member port - it receives multicast traffic rather than requesting it. IF3 (B) connects to a host that has not joined any multicast group, so no IGMP Report was received on that port and it holds no membership state.

Memory tip: Think of member ports as "subscribers" - a port only becomes a member port when a host actively subscribes (sends an IGMP Join). Router-facing ports and silent hosts are never member ports, even though multicast traffic may pass through them.

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