One day I discovered that my Internet Service Provider's Domain Name System (DNS) servers were not working as expected. I did not see the usual "can't find the server" message when I made a typo in Safari. Instead, a search engine appeared offering to help me find what I was looking for.
I realized that this sort of DNS response was undesirable, as it presents security and privacy issues, so I immediately installed the pdnsd proxy DNS server and configured it to query the root servers directly. Since then, my ISP has removed that unwanted "feature," but I continue to use pdnsd for peace of mind.
And now, I've documented how to use the same setup on other Mac OS X version 10.4 computers.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060304191416866