This read-only Counter64 counts queries discarded because the ingress port was down at the moment the query arrived. A nonzero count right after a known link flap is expected and benign, but a steady trickle on a port that monitoring shows as up points to a state-tracking mismatch worth investigating; because it is drawn from the current, still-open 24-hour bin for today, the number keeps climbing until midnight rollover, so it should be read as "so far today" rather than a finished daily total. On a residential VLAN used for multicast video delivery, a count of 3,056 over today so far 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.