HTTP header "Via:1.1 nc1 (NetCache NetApp/6.0.5P1)" stops IIS6 gzip compression

Question

The request I sent is accept gzip but the response is not compressed, instead, I received some header

Via:1.1 nc1 (NetCache NetApp/6.0.5P1)

I guess this is to do with my ISP since it works perfectly on my home computer.

Any idea how to get the response compressed?

Request header

GET /test.aspx HTTP/1.1
Host    this.is.example.com
User-Agent  Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3 (.NET CLR 3.5.30729)
Accept  text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive  300
Pragma  no-cache
Cache-Control   no-cache

Response header

HTTP/1.1 200 OK
Date    Mon, 01 Dec 2008 19:53:40 GMT
Content-Length  6099
Content-Type    text/html; charset=utf-8
Cache-Control   private
Server  Microsoft-IIS/6.0
X-Powered-By    ASP.NET
X-AspNet-Version    2.0.50727
Via 1.1 nc1 (NetCache NetApp/6.0.5P1)
Expires 0
Cache-Control   no-cache
// I expect content-encoding to be gzip here

Thanks in advance.

Answer 1

There's no mechanism to force response compression. Accept-Encoding: gzip only tells the webserver/proxy that it MAY compress the response, not that it MUST encode the response. There are many webservers and proxies that don't support gzip out of the box, or have it configured off by default.

The Via header that you found is frequently inserted by proxies that connect to the intended webserver on your behalf, and is informational. It's unrelated to your compression woes.