See the file COPYING for copying restrictions.

This package contains ypcat, ypmatch, ypset, ypwhich, yppasswd,
domainname, nisdomainname and ypdomainname. 

yp-tools 4.x has full NIS IPv6 support if compiled and linked against
libnsl >= 1.0.4 and libtirpc >= 1.0.1.

yp-tools should be compiled on Linux against libnsl from
https://github.com/thkukuk/libnsl
or
http://www.linux-nis.org/download/libnsl/

Support for the glibc libnsl and sunrpc is deprecated, since the 
glibc version of libnsl and sunrpc are in maintenance mode and may 
be removed in the future.