This policy setting limits the number of ranges that can be added to a file in a BITS job. By default files in a BITS job are limited to 500 ranges per file. You can use this setting to raise or lower the maximum number ranges per file. If you enable this policy setting BITS will limit the maximum number of ranges that can be added to a file to the specified number. If you disable or do not configure this policy setting BITS will limit ranges to 500 ranges per file. Note: BITS Jobs created by services and the local administrator account do not count toward this limit.
Network\Background Intelligent Transfer Service (BITS)
At least Windows Vista