A fast, secure, modular, sane alternative to the whole BIND mess, and a darned pleasant way of both publishing your DNS data to the world, and of resolving those pesky hostnames to IP addresses and such.
djbdns separates the two different services collectively known as DNS -- resolving proxy service, provided by the dnscache program, and content publishing, provided by a suite of daemons. You pick the daemon that matches the type of content you wish to publish. The general-purpose content-publishing daemon for standard UDP service is tinydns.
One of the biggest differences between djbdns and the Buggy Internet Name Daemon is that djbdns does not constantly reinvent the wheel. To replicate data across servers, djbdns can use whatever method you would normally use to do so -- rsync, rsync over ssh, ftp, http, smoke signals, or whatever. BIND, on the other hand, uses its own inflexible protocol to replicate DNS data.
Written by djb (Daniel J. Bernstein), his djbdns page is at http://cr.yp.to/djbdns.html , while the djbdns community site is at http://www.djbdns.org/ .