This policy setting specifies whether the computer will act as a BITS peer caching client. By default when BITS peer caching is enabled the computer acts as both a peer caching server (offering files to its peers) and a peer caching client (downloading files from its peers). If you enable this policy setting the computer will no longer use the BITS peer caching feature to download files; files will be downloaded only from the origin server. However the computer will still make files available to its peers. If you disable or do not configure this policy setting the computer attempts to download peer-enabled BITS jobs from peer computers before reverting to the origin server. Note: This policy setting has no effect if the "Allow BITS peer caching" policy setting is disabled or not configured.
Network\Background Intelligent Transfer Service (BITS)
At least Windows Vista