The resolution of the entities defined in RFC 2307 is generally performed
by a set of UNIX C library calls (such as getpwnam() to return the attributes
of a user).  The nss_ldap module provides the means for Solaris and Linux
workstations to get this information (such as users, hosts, and groups) from
LDAP directories.  The module is the reference implementation of RFC 2307,
and has been studied by vendors such as Sun (who developed the original
Name Service Switch interface).