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From "howard chen" <>
Subject Re: [users@httpd] Force IE to cache
Date Fri, 03 Oct 2008 03:10:25 GMT

Thanks for you valuable comments...

On Fri, Oct 3, 2008 at 4:24 AM, André Warnier <> wrote:
> I have not verified, but maybe you are interpreting the rules of caching
> a bit more extensively than what the HTTP RFCs really say.
> It may be that, by using your various HTTP headers, your server is doing
> what it can to "suggest" to the browser that it should cache this object and
> not ask again for 10 years.  But maybe also, the RFC says that the client is
> not "forced" to respect this, and "can" ask again if the content has been
> replaced in the meantime or not.
> After all, you are seeing 304 responses from the server.  This means that
> the browser has requested an object, but told the server "only if not
> modified since..", and the 304 of the server is "No, it has not been
> modified since then, you do not need to reload it". And consequently the
> browser uses its cached version, and it does not insist. (I suppose, because
> otherwise you would see another request from the browser, and another 200 OK
> response from the server).


I have done an experinment with both IE6 & IE7, using MS default image:

In my experinment, I have set the files to expire in 10 years later,
so, on the first request, the file
would be downloaded and cached for 10 years. (I confirm this as I can
see the expire date being set correctly in
~\Local Settings\Temporary Internet Files\...)

Then, in the repeated request, IE6/IE7 would not contact the web
server for any kind of validation
, e.g. If-modified-since, it will use the cache directly, so there
should not be any 304 in my server log.

Since I have check with both IE6 and IE7 and can confirm this, unless
user press F5 for reload,
304 will be sent out.

However, I still don't belive 50% of my users will press F5 for normal
usage and end up with 50% of 304, as compare to 200.


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