Something fishy

Poul-Henning Kamp phk at
Thu Aug 10 21:29:37 CEST 2006

In message <2152. at>, "Anders Berg" 

>(andersb) fw:andersb $ HEAD
>200 OK
>Cache-Control: max-age=900
>Connection: close
>Date: Thu, 10 Aug 2006 18:38:23 GMT
>Accept-Ranges: bytes
>Age: 43
>ETag: W/"2b400e-28af1-44db7d1e"
>Server: Apache/1.3.27 (Unix)
>Content-Length: 166641
>Content-Type: text/html; charset=iso-8859-1
>Expires: Thu, 10 Aug 2006 18:53:23 GMT
>Last-Modified: Thu, 10 Aug 2006 18:38:22 GMT
>Client-Date: Thu, 10 Aug 2006 18:39:06 GMT
>Client-Response-Num: 1
>X-Cache: HIT from
>X-Cache: HIT from
>(andersb) fw:andersb $ HEAD
>200 OK
>Connection: close
>Date: Thu, 10 Aug 2006 18:37:27 GMT
>Via: 1.1 varnish
>Age: 100
>ETag: "2b400e-288d5-44db7c55"
>Server: Apache/1.3.27 (Unix)
>Content-Length: 166101
>Content-Type: text/html; charset=iso-8859-1
>Expires: Thu, 10 Aug 2006 18:52:27 GMT
>Last-Modified: Thu, 10 Aug 2006 18:35:01 GMT
>Client-Date: Thu, 10 Aug 2006 18:39:07 GMT
>Client-Response-Num: 1
>X-Varnish: 2002714009 2002603403
>The only differences I see are these (except that the doc's are somewhat
>different because of different timeouts):
>Cache-Control: max-age=900 on Squid, no header like this on Varnish.

This shouldn't matter when the object has an Expires header.

I guess if you computers time were off, we would be more safe with
an max-age as well.

Create a ticket on it.

>The next one is weird:
>ETag: W/"2b400e-28af1-44db7d1e" on Squid
>ETag: "2b400e-288d5-44db7c55" on Varnish.

This is whatever we got from the backend, Varnish does not touch
ETag in anyway.

>Every ETag from Squid has a W/ before the tag. This is new to me, and I
>don't know the implications. It's obviously consistent across all Squid's.

W/ means weak.  I tried to wrap my head around why they wanted that
in the RFC and failed.  It was probably a good idea to somebody.

>Accept-Ranges: bytes on Squid but none on Varnish, but that's not whats
>causing this.

Correct, we don't accept ranges.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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