The nss_resinit is a module for the nsswitch subsystem which makes
resolver(3) reread /etc/resolv.conf when it is updated.  In the
traditional implementation of resolver(3) it is initialized by the
application once and never reread /etc/resolv.conf after that even if
the file is updated.  This module is useful especially when name
servers in /etc/resolv.conf are changed frequently as seen in mobile
environment.