[squid-users] PUT requests, squid, and round-robin DNS

Hi, I'm having a problem with a site we run where under certain
conditions POST requests are not being handled as expected.

The site runs on two servers (both Win2003 with IIS6) with same fqdn,
i.e. round robin DNS. Session state data is maintained out-of-process
in a database which is synchronised between servers. For 95% of
functionality it works very well. However, when the client submits a
POST which should result in a 302 redirect we get strange behaviour.

- if client connects directly to the server without going through
Squid, the 302 is returned correctly.
- if DNS is altered to resolve to only one server, then a client
connecting through Squid doing such a POST results in 302, correct
behaviour.
- if using round-robin DNS and client POSTs via Squid, a 200 response
is sent back to the client and the original page displayed again
(incorrect behaviour). But refreshing the page reposts the data
correctly resulting in the 302.

There doesn't appear to be any other problems with the setup - all
GETs for instance work correctly, session data is correctly maintained
between servers, etc. Squid is configured to go direct for the site
so no problems with caching. I'm not using balance_on_mulitple_ip (it
might do the job for our local users but wouldn't fix the problem for
people using ISP proxies etc)

Squid is version 2.5.STABLE9 on Debian sarge. Web site is ASP.Net on IIS6.

Has anyone seen a problem like this before? Any ideas how to troubleshoot?

Thanks
Received on Thu Jun 01 2006 - 22:11:42 MDT