This read-only Counter64 counts the number of times this PM instance timed out waiting for hosts to reply with membership reports after a query. Admins use this to catch unresponsive or powered-off multicast receivers before the switch prunes them from the group and a subscriber notices the stream stop; because it is drawn from this table's currently-accumulating, short-interval bin, it reflects only the last few minutes of activity, so it's the value to watch for a fast-forming problem rather than a long-term trend. On an access port serving a multi-dwelling unit, a count of 1,945 over the last 15 minutes is the kind of number an admin would trend against the join/leave rate on the same port to judge whether it's normal channel-surfing or an anomaly worth a closer look.