[squid-users] Unexpected MISSes; patching Accept-Encoding via header_access/header_replace?

From: Gordon Mohr <gojomo_at_archive.org>
Date: Sun, 28 Sep 2008 19:19:46 -0700

Using 2.6.14-1ubuntu2 in an reverse/accelerator setup.

URLs I hope to be cached aren't, even after adjusting passed headers.

For example, I request an URL with FireFox, get the expected MISS. Then
request same URL with IE, get unexpected MISS when I'd like a HIT. Then
request same URL with Chrome, get MISS instead of HIT. Finally, request
with Safari, finally get a HIT.

I gather that the key variable is the differing Accept-Encoding headers:

Firefox: gzip,deflate
IE: gzip, deflate
Chrome: gzip,deflate,bzip2
Safari: gzip, deflate (same as IE, hence the HIT)

My theory was that stripping the varied header values and replacing them
with the lowest-common-denominator (and the only variant ever returned
by the parent server) could help. So I added the following to my squid

header_access Accept-Encoding deny all
header_replace Accept-Encoding gzip

However, this has not changed the HIT/MISS pattern at all.

Any other ideas for letting all these browsers share the same cached

(Bonus question: My inner-server's 404 responses include a 24-hour
Expires header. Will these be cached by squid for the declared period or
the shorter negative-ttl? The info at
is unclear which wins.)

- Gordon @ IA
Received on Mon Sep 29 2008 - 02:19:46 MDT

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