A file is multicast from an error-correcting multicast apparatus to a plurality of endpoints forming a first multicast group, over a network segmented into at least second and third multicast groups. The second and third multicast groups are subsets of the first multicast group. Given ones of the endpoints are assigned to the second and third multicast groups based on likelihood of experiencing similar errors. At the error-correcting multicast apparatus, over the network, a retransmission request is obtained from a first one of the endpoints, based on at least one of loss and corruption of a portion of the file during the multicasting of the file to the first one of the endpoints. The portion of the file is retransmitted, via multicasting, over the network, to one of the second and third multicast groups.