The HTTP Range request header indicates the part of a resource that the server should return.
Several parts can be requested at the same time in one Range header, and the server may send back these ranges in a multipart document.
If the server sends back ranges, it uses the 206 Partial Content status code for the response.
If the ranges are invalid, the server returns the 416 Range Not Satisfiable error....(if the requested resource was less than 1000 bytes long, for instance)...