This read-only value, in seconds, is the time remaining until the host assumes no IGMPv1 routers are present on the interface, counting down after hearing an IGMPv1 query. While this timer is nonzero, the host continues replying to queries using version-1-style membership reports for backward compatibility, so an admin can use it to detect whether legacy IGMPv1 routers are still active on the segment. For example, seeing igmpInterfaceVersion1QuerierTimer count down from a nonzero value confirms that an IGMPv1 router recently sent a query on that interface's subnet.