This sets, when the modem is acting as an IGMP server or querier, how often in seconds it sends IGMP membership queries to check which groups still have active listeners. A shorter query period detects a group with no remaining listeners faster, freeing that multicast bandwidth sooner, but at the cost of more frequent query traffic consuming a small amount of the same satellite bandwidth being conserved. Setting this to 60 means the modem checks every minute whether each multicast group still has listeners, striking a balance between quick cleanup of dead groups and query overhead.