BIND9 (Berkeley Internet Name Domain)

I find that it's pretty easy to install and configure (although examples are helpful, heh).

As for security holes, I haven't heard of one for a while...

Can one gazillion name servers be wrong? ;)

antiquated, overly complex, insecure. this is the piece of software that tops the list for security vulns. it was useful in it's day, but some people just wont let go.