[squid-users] IPv4/IPv6 fallback

Hello,

I'm running 3.1.19 (from Ubuntu 12.04 package). squid does a great job of
picking ipv6 first and using that (for sites that have AAAA and respond).

The problem is when a site's ipv6 connectivity is broken - squid doesn't
fall back to ipv4. An example at the moment is isc.sans.edu. I contacted
them and they may fix this by the time folks read this message though.

I found in the release notes for 3.1.3 something that I think matches this
issue:

http://ftp.ist.utl.pt/pub/squid/squid-3.1.3-RELEASENOTES.html#ss1.1

---
Currently known issues which only depends on available developer time and 
may still be resolved in a future 3.1 release are:
 	IPv4 fall-back occasionally failing on dual IPv4/IPv6 websites.
---
However, I can't seem to find any further mention of this, i.e. that it 
was fixed in newer version release notes, changelogs etc.
So to summarirze:
www.site.com has A 192.168.1.100 and AAAA 2001:db8::100
2001:db8::100 is 'broken' in some way.
192.168.1.100 is healthy.
squid gets 'stuck' trying 2001:db8::100 and never falls back.
Thanks in advance.
--
Brandon Applegate - CCIE 10273
PGP Key fingerprint:
830B 4802 1DD4 F4F9 63FE  B966 C0A7 189E 9EC0 3A74
"SH1-0151.  This is the serial number, of our orbital gun."