What new feature in IGMPv2 allows a host to indicate it has stopped listening to a multicast group?

In IGMPv2, the Leave Group message is a significant feature that allows a host to notify the local router that it has stopped listening to a specific multicast group. This is important because it enables the router to manage multicast group memberships more effectively. When a host sends a Leave Group message, it indicates that it no longer wishes to receive traffic destined for that particular multicast address.

This message triggers the router to potentially remove the host from the multicast forwarding list and may prompt it to check if other hosts are still part of the group. This process helps in optimizing network resources by minimizing unnecessary multicast traffic.

The other options have their own functions within IGMP. For instance, the Membership Query is sent by the router to determine which hosts are still active in a multicast group, while Group Specific Query is a more targeted version of that query, addressing specific multicast groups. Querier election refers to the process of selecting a designated router to handle IGMP communications, but it does not relate to informing the router about a host leaving a multicast group. Thus, the Leave Group message is the specific feature that fulfills the requirement outlined in the question.