There is described a system of operating a network entity to distribute a media stream in a communications network. A plurality of different versions of the media stream are available from a content source, each version having a respective quality level different to that of the other versions and each version of the media stream comprises a plurality of consecutive portions. A first request is received from a user device for a portion of a first one of the versions of the media stream stored at a content source and a caching procedure is performed in response to receiving the first request. The caching procedure comprises requesting from the content source at least one portion of at least one of the other versions of the media stream or at least one other portion of the first one of the versions of the media stream; receiving the requested at least one portion or the at least one other portion; and causing the received at least one portion or the at least one other portion to be cached at a cache in the communication network.