This read-write enable/disable switch controls the IGMP querier function for this VLAN; its stored source DESCRIPTION text ('the IGMP snooping state of this VLAN') is a near-duplicate of the sibling swIGMPSnpCtrlState object's description and looks like a copy-paste artifact rather than an accurate description of what QuerierState actually configures, so this reading is based on the object's own name and its position next to swIGMPSnpCtrlQuerierRole/QuerierIP. Admins enable it on the VLAN that should originate IGMP queries (in the absence of a multicast router) so that snooping has a periodic query/report cycle to work with, and disable it where an upstream router or another switch already provides that querier function. Running two competing queriers on the same VLAN, or none at all, is the scenario admins use this setting to avoid.