Re: [squid-users] disabling use of If-Modified-Since

From: Stefan Palme <kleiner@dont-contact.us>
Date: Fri, 10 Mar 2006 09:55:34 +0100

> > , but this seems to have no effect. A client sending the
> > "If-Modified-Since" header received a 304 (not modified) in some cases,
> > so I guess the If-Modified-Since header has not been removed from the
> > request.
>
> Most likely it only gets removed from forwarded requests. Cache-hits
> probably still accounts for the If-Modified-Since.
>
> You should however never see any If-Modified-Since to the backend server
> if you have blocked this header.

This is true. The "If-Modified-Since" client header is handled by
squid, not the backend server.

> What is the reason you want to block If-Modified-Since? Most people
> likes this as it cuts down on the bandwidth usage by not transmitting
> objects the client already has..

Because some customers have a strange behaviour with IE (and *only* with
IE): some images on one of our websites don't appear in their browsers.
After sniffing the traffic I've discovered, that IE sends a GET-Request
for these images with an "If-Modified-Since" header. Squid responses
(correctly) with a 304 (not modified). So IE should use the image from
its local cache, but it does not - there is no image at all on the
web page.

I guess this is a problem with IE's local cache, and I wanted to
circumvent this by never responsing with 304, but letting squid
return the image instead...

Thanks
-Stefan-
Received on Fri Mar 10 2006 - 01:55:53 MST

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