Being a frequent OpenVPN/TunnelBlick user these days, I want to change my DNS resolver configuration after having established a tunnel. Until very recently I was under the impression any decent Un*x-like OS has its resolver configuration in /etc/resolv.conf. Well, this doesn’t apply for OSX. The resolv.conf in /etc is only a read-only mirror of the resolver configuration; changes in this file will not be propagated back to the resolver. No, this setting needs to be manipulated in a “dynamic store maintainted by configd(8)” [AFP548: Using scutil to set DNS server]. Thank you very much, Apple.

UPDATE: The above apparently only applies to Tiger; the issue has been discussed in several other places before