mcast_solicit

file: /proc/sys/net/ipv4/conf/interface/mcast_solicit
variable: net.ipv4.conf.interface.mcast_solicit
Official reference

The maximum number of multicast probes in INCOMPLETE state, when the associated hardware address is unknown. Defaults to 3.

Nb: per interface setting (where “interface” is the name of your network interface); “all” is a special interface: changes the settings for all interfaces.

source