logresolve - reverse DNS lookup engine logresolve is a free HTTP access log post-processor. logresolve can speed up your web server by allowing you to defer reverse nameservice resolution to a more convenient time or machine. Linux, SGI, Solaris, and other Unix systems. (Dec 1998)
Posadis - DNS server for Unix and Windows Posadis is a Domain Name Server, primarily designed for Unix and Windows platforms, which aims to be easy to use and (well, obviously) stable and fast. Posadis is currently what we like to call an "authoritive-plus" server (Dec 2002)
Books about DNSA complete list of books on DNS available through Amazon.COM