User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6) Gecko/20040206 Firefox/0.8 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6) Gecko/20040206 Firefox/0.8 The "Vary" header is used by the server to indicate to the client that the page it's returning may change if one of the specified headers change. For example, "Vary: Accept-Encoding" is used to indicate that the entity may be different if the client specifies a different "Accept-Encoding:" request header. However, while "Vary: Accept-Encoding" is handled correctly by Mozilla, "Vary: Cookie" is not. Mozilla seems not to recognise "Vary: Cookie" at all, and treat it instead like "Vary: *". This means that Mozilla is unable to cache a page with "Vary: Cookie", even if no cookies exist or all cookies remain constant. Reproducible: Always Steps to Reproduce: 1. Visit http://www.arcticforest.com/testvary.php 2. Navigate away to a different page. 3. Return to http://www.arcticforest.com/testvary.php, and see if your browser has to revalidate the page with the server. Actual Results: Always revalidates the page with the server. Never returns a cached version without revalidating. Expected Results: The software should have realised that since we have no cookies set, or our set cookies haven't changed, that it can return the cached version of the page without contacting the server. Please see the entry for "Vary" in the HTTP specification here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.44 MS Internet Explorer (6.0) treats Vary: Cookie correctly.

Note: on further inspection, it appears that Internet Explorer does not, in fact, handle Vary: Cookie correctly as I stated above, although for a different reason. While it really doesn't matter what IE does here, I thought I'd mention that.

This looks like a duplicate of bug 94123....

*** This bug has been marked as a duplicate of 94123 ***