pdnsd reports no IP for www.forbes.com after any attempt to access the site via HTTP

[mathew]

Binary package hint: pdnsd

This is a really weird one... I can empty the cache for pdnsd, then ping www.forbes.com, and it resolves. However, if I attempt to make an HTTP connection, it no longer resolves, and then never resolves again until I clear the cache again.

# ping www.forbes.com
PING www-origin.forbes.com (63.240.4.179) 56(84) bytes of data.
64 bytes from www.forbes.com (63.240.4.179): icmp_seq=1 ttl=40 time=64.6 ms
^C
--- www-origin.forbes.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 64.648/64.648/64.648/0.000 ms
root@w510:/home/meta# curl www.forbes.com
curl: (6) Couldn't resolve host 'www.forbes.com'
root@w510:/home/meta# ping www.forbes.com
ping: unknown host www.forbes.com
root@w510:/home/meta#

The problem seems to be that www.forbes.com doesn't exist in IPv6, and somehow this is being taken to mean that it doesn't exist in IPv4 either.

What confuses me is that I only see the problem with www.forbes.com, not with any other web site. And only on one machine--I have another machine running pdnsd that doesn't seem to have the problem.

The machine which shows the issue has a VPN active, but the VPN DNS servers are configured with include= statements so as not to be used for this query. The machine which shows the issue also has the other machine configured as a DNS server. Other than that, their pdnsd configuration is identical.

Any assistance you could give in tracking down the cause of the problem would be appreciated.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: pdnsd 1.2.7-par-1.1
ProcVersionSignature: Ubuntu 2.6.32-23.37-generic-pae 2.6.32.15+drm33.5
Uname: Linux 2.6.32-23-generic-pae i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Thu Jul 22 16:02:40 2010
InstallationMedia: Kubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100427)
SourcePackage: pdnsd