[smokeping-users] DNS probe failing for one host

[Lars Hecking]

 My current smokeping-2.4.2 setup was working fine for over 8 months, and
 about 9 days ago, DNS probes for one particular host started failing,
 indicated by a succession of

Tue Mar  3 15:30:14 2009 - got TERM signal, terminating.
Tue Mar  3 15:33:13 2009 - DNS: 172.23.1.1: timeout (26 s) reached, killing the probe.
Tue Mar  3 15:33:13 2009 - got TERM signal, terminating.
Tue Mar  3 15:36:13 2009 - DNS: 172.23.1.1: timeout (26 s) reached, killing the probe.

 These probes fail for both master and a remote slave. I have 18 DNS and
 25 AnotherDNS probes configured, and this is the only one that fails.
 Ping probes work fine for all of the monitored hosts.

 However, while this probe is failing, I can manually run dig @172.23.1.1 on
 the smokeping host and get a result within a few hundred milliseconds. Neither
 the smokeping host nor the target were rebooted in the past ten days.

 Any ideas how to approach this? I'm completely baffled.