If the $PWDIR/security/passwd.adjunct file is present, C2 security is started automatically. ($PWDIR is defined in /var/yp/Makefile.) The C2 security mode uses the passwd.adjunct file to create the passwd.adjunct NIS map. In this implementation, NIS allows you to use both the passwd.adjunct file and shadow file to manage security. The passwd.adjunct file is processed only when you type the following.
# make passwd.adjunct