[Mod_gzip] MSIE cannot handle Vary header(s)

[mod_gzip@lists.over.net]

Hello again...

I forgot to mention one or two things that relate to
this MSIE 'caching' issue.

Some of these things might be obvious to most but
not obvious to others and they DO MATTER.

1. Despite what you might think... MSIE will start 
refusing to cache anything locally if you fall even
1 byte below what you have set for your 
Maximum Cache Size. If you have set your
Maximum Cache Size to 63 megabytes and
you fall to only 62 megabytes free then MSIE
will stop caching everything but COOKIES
on the local machine. The COOKIES keep 
being written until you run out of disk space
but NOT the 'other stuff'.

This condition would have the same visual effect
as what is being reported with regards to "Vary:"
and is probably why Michael S. says that he
has 2 identical boxes hitting 2 identical Servers
and one will cache and the other won't. Perhaps
ONE of the client boxes has dipped below
the "Max Cache Size" as far as free disk space goes.

2. If you have turned on the MSIE option to "Check for Newer
Versions of Pages on Each Visit" then this also applies
to the BACK/FORWARD buttons and selections made
from the History list and would also appear to cause
the same "Nothing is being cached" behavior.

3. This one is just to dispel an 'urban legend'.
There was once a rumor going around that MSIE would
never 'cache' a page if it came from an address of
127.0.0.1 ( A Server running on the same machine ).
This is NOT TRUE. It makes no difference if the
Server is local ( 127.0.0.1 ) or not. MSIE will 
behave the same with regards to local browser
object caching. It doesn't care where it came from.

So if anyone wants to to any more MSIE testing
the easiest thing to do is just fire up both
Server and Client on the same box. The test
results will still be accurate.

Later...
Kevin