This sets how many consecutive missed query responses are tolerated before the unit actually removes a host from a multicast group and stops forwarding that stream to it. It's a tradeoff dial between cleaning up stale group memberships quickly and tolerating the occasional lost query or response packet common on a satellite path. For example, raising this value from a low setting gives more tolerance for the packet loss inherent to a marginal satellite link, at the cost of a slower cleanup when a group genuinely has no listeners left.