Brian Masney and S.Kalyanasundraram and maintained for application to
  the DHCP-4 sources by David Cantrell has been included.  Please be
  advised that these sources were contributed, and do not yet meet the
  high standards we place on production sources we include by default.
  As a result, the LDAP features are only included by using a compile-time
  option which defaults off, and if you enable it you do so under your
  own recognizance.  We will be improving this software over time.
  [ISC-Bugs #17741]