Dear Yutaka, when using delegate 9.7.7 as a http origin server, it seems that the 304 (not modified) response does not conform exactly to the http specifiation: HTTP/1.1 304 Not modified Date: Wed, 12 Dec 2007 10:43:46 GMT Server: DeleGate/9.7.7 DeleGate-Ver: 9.7.7 (delay=7) MIME-Version: 1.0 Content-Type: image/jpeg Content-Length: 2791 Last-Modified: Wed, 28 Nov 2007 02:40:56 GMT Proxy-Connection: keep-alive, timeout=50, maxreq=48 => "This type of HTTP response MUST NOT contain a body, but a non-zero content-length was returned." Apache sends a much shorter response like this: HTTP/1.1 304 Not Modified Date: Wed, 12 Dec 2007 10:59:18 GMT Server: Apache/2.2.3 (Linux/SUSE) Connection: close I do not think that the header will cause any problems, I just wanted to let you know. With kind regards, Matthias