varnish fetching, stroring and serving cached 404 from backend server

Michael Loftis mloftis at
Wed Aug 18 04:59:45 CEST 2010

Varnish caching, or not caching, is completely controlled by the VCL.  Not 
having yours noone can help you.  However, the *default* VCL makes anything 
with a Cookie or HTTP Authentication header from the client uncacheable.

--On Tuesday, August 17, 2010 1:13 PM -0700 David Birdsong 
<david.birdsong at> wrote:

> I've been struggling to understand why and how varnish is deciding to
> cache a 404 response from a backend.  It's very tough to reproduce.
> I've thrown millions of test URLs at varnish where my testing
> application will respond back randomly with a 404 and I can't trigger
> it.  Only user traffic is able to trigger this weird behavior.
> Anybody have any experience with this?
> Here's a varnishlog of a 404.
> I'm working to capture the varnishlog of the resource actually getting
> fetched and stored.
> _______________________________________________
> varnish-misc mailing list
> varnish-misc at

More information about the varnish-misc mailing list