IE6 vary debug

varydebugie6

Two servers, one url : a PNG image.

On the first server, empty cache:

Headers received :
HTTP/1.1 200 OK
Date: Wed, 24 Nov 2010 15:28:13 GMT
Server: IBM_HTTP_Server
Vary: Host
Last-Modified: Wed, 24 Nov 2010 13:48:36 GMT
ETag: "1c2a1b-429-495ccbeee5500"
Accept-Ranges: bytes
Content-Length: 1065
Keep-Alive: timeout=10, max=96
Connection: Keep-Alive
Content-Type: image/png

When refresh, headers sent by IE6 :
GET $imgurl.png HTTP/1.1
Accept: */*
Accept-Language: fr
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; InfoPath.1; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Host: fr.musha:84
Connection: Keep-Alive

On the other server, empty cache:

Headers received :
HTTP/1.0 200 OK
Date: Wed, 24 Nov 2010 15:31:04 GMT
Server: IBM_HTTP_Server
Vary: Host
Last-Modified: Tue, 23 Nov 2010 14:54:51 GMT
Accept-Ranges: bytes
Content-Length: 1065
Cache-Control: max-age=604800, public
Content-Type: image/png
Set-Cookie: BIGipServerWEB-B2C=2252278740.20480.0000; expires=Wed, 24-Nov-2010 15:46:04 GMT; path=/
X-Cache: MISS from [...]
X-Cache-Lookup: HIT from [...]
Via: 1.0 [...]
Proxy-Connection: keep-alive

When refresh, headers sent by IE6 :
GET http://www.viamichelin.fr/img/ihm/sprites/InputBgV10.3.0.png HTTP/1.0
Accept: */*
Accept-Language: fr
Proxy-Connection: Keep-Alive
If-Modified-Since: Tue, 23 Nov 2010 14:54:51 GMT; length=1065
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; InfoPath.1; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Host: www.viamichelin.fr
Pragma: no-cache
Cookie: BIGipServerWEB-B2C=2252278740.20480.0000

As you can see, if modified since is sent on the second server.