I have a squid used as reverse proxy of a apache web server. The apache web server run module mod_deflate. when I checked apache log file, I found that some web pages were not compressed, some were. the Logformat is : LogFormat "%h %l %u %t \"%r\" %>s %b %{Accept-Encoding}i %{User-agent}i %{outstream}n/%{instream}n (%{ratio}n%%)" common the log is like this: 192.168.0.21 - - [08/Aug/2005:22:40:01 +0800] "GET web page url" 200 19290 - Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Maxthon; .NET CLR 1.1.4322) -/- (-%) I found that the web page which squid send to web server does not have Accept-Encoding headers, but the client is Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Maxthon; .NET CLR 1.1.4322), whcih can probably send sent Accept-Encoding headers. Could anyone tell me, why this happened? Looking forward to your reply. Best Regards,