Which of the following statements about IGMPv2 routers maintaining segment group membership are correct? (Multiple choice)

Question

Options

• AAfter receiving the Leave message, the router immediately removes the members of the group
• BThe router maintains the group membership
• CThe router maintains a timeout timer for each group membership
• DAfter the router sends a general group query message, all receivers need to respond within the maximum response time

• A
  9% (2)
• B
  73% (16)
• D
  18% (4)

Explanation

B and C are correct because IGMPv2 routers actively maintain a membership table of which multicast groups have active listeners on each segment (B), and for each entry they run a timeout timer - if no Membership Report is received before expiry, the group is pruned (C). These two mechanisms work together to keep group state accurate without flooding the network.

A is wrong because IGMPv2 does not immediately remove a group on receiving a Leave message. Instead, the router sends a Group-Specific Query to check whether any remaining members still exist; only if no response arrives within the maximum response time is the group removed. This prevents a single host's departure from cutting off the rest.

D is wrong because IGMPv2 uses a report suppression mechanism: each host picks a random delay within the maximum response time and, if it hears another host's report for the same group first, it cancels its own. As a result, typically only one host responds per group - not all receivers.

Memory tip: Picture the router as a librarian keeping a card catalogue (B) with due-date stamps (C). When someone returns a book (Leave), the librarian checks if anyone else still has it checked out before deleting the record (not A). And when asking "who has this book?", the first person to raise their hand lets everyone else lower theirs (not D).

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