From
http://www.isc.org/downloads/libbind/
The libbind functions have been separated from the BIND suite as of BIND
9.6.0. Originally from older versions of BIND, they have been continually
maintained and improved but not installed by default with BIND 9. This
standard resolver library contains the same historical functions and
headers included with many Unix operating systems. In fact, most
implementations are based on the same original code.
At present, NetBSD maintains libbind code, now known as "netresolv".
uses them.
Now, we have res_nupdate and res_nmkupdate as well, but they are
still based on our old resolver for binary backward compatibility.
So, they don't provide new features such as TSIG support.
Reported by: pointyhat via kris
