Data objects are delivered over a packet-switched network and receivers receive encoded symbols, such as repair symbols, broadcast or multicast, with sufficient information to form requests for additional symbols as needed based on what source symbols or sub-symbols are needed or missing. The requests can be made in a unicast or request fashion. Requesting and broadcasting might be done by different entities. A broadcast server can generate and store repair symbols while a source server can store content in source form. A request can be a unicast HTTP byte-range request, such as a URL, starting position and length. Requests might be aligned with starting positions of files. A receiver can calculate starting and ending byte positions of symbols or sub-symbols in a file and get indications that conventional HTTP servers are usable for file repair. Repair servers can request broadcast of repair data when byte-range requests from multiple receivers overlap.