DATA TRANSFER SYSTEM

The origin server has content in block units formed by dividing the content, and includes content processing means for providing each of the blocks with an identifier including a domain which identifies each substream including the blocks. The domain resolution server includes assignment means for determining a proxy server which should be assigned for each domain identifying the substream. When the assignment means requests a proxy server of an adjacent parent site located upstream, on a path from a site in which the origin server is disposed to an edge site accessed by the client, to resolve a domain of one substream from the proxy server of the own site, the assignment means makes a domain resolution request to a domain resolution server of the parent site for assigning a proxy server, disposed in the parent site, to each of all substreams.