Mozilla 1.7.2 could not do both ipv6, and ipv4 for ldap. In file:
pkgsrc/www/mozilla-gtk2/work/mozilla/directory/c-sdk/ldap/libraries/lib
prldap/ldappr-int.h
At line 44 I changed:
#define PRLDAP_DEFAULT_ADDRESS_FAMILY  PR_AF_INET6
to
#define PRLDAP_DEFAULT_ADDRESS_FAMILY  PR_AF_INET

It looked like it would not take to much to change the code to support
both, but since the quick fix worked for me, I never got around to it.