This read-only Counter64 counts queries discarded because the ingress port was in a blocking state (for example, held down by spanning tree or an access-control action) when the query arrived. This ties multicast query loss directly to L2 loop-prevention or security state on the port, useful when troubleshooting why an IPTV stream briefly drops during a topology change; because it is drawn from the most recently completed short-interval historical bin, it is a closed record of the interval right before the current one, useful for checking whether a problem seen right now had already started in the previous window. On an access port serving a multi-dwelling unit, a count of 1,840 over the last completed collection window 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.