An example system includes a network having interconnected routers, a multicast source to transmit data through the network for receipt by receiving host devices, and a query agent communicatively coupled to each router of the interconnected routers. The query agent is to generate a flow tree for multicasting of the data from the multicast source to each receiving host device, the flow tree including flow paths from the multicast source to each receiving host device, query each router to determine a status of at least one flow path of the flow tree, and identify an anomaly associated with at least one router in the at least one flow path.