When a range request comes into ATS and the underlying object must be revalidated or is expired, it appears that ATS serves the entire object to the client and ignores the requested range in the Range header. While range requests are not required to be supported, in this case they are supported in ATS, and the difference in behavior can lead to unexpected results when the client sees the 200 and full object instead of the 206. Ideally ATS would revalidate, fill the new object as necessary, and return the requested range to the client.