Very important point made about knowing the extended features of each directory product. For example, Active Directory sets a hard limit on the number of entries returned by a search. The way around this is to use the Paged Results control extension (good feature). Problem is that while this control is supported on AD and OpenLDAP it *is not* thus far supported by any of the Netscape derived directory products (i.e. Sun, Fedora/Red Hat). Another extension with uneven support is Server Side Sort (not my favorite feature). This is available on Sun/Fedora/Red Hat *but not* on Active Directory or OpenLDAP. The foregoing brings up another point. Although programming to the LDAP protocol itself (apart from various vendor extensions) is pretty uniform the configuration of each individual directory may not necessarily be. Maximum number of results returned, restrictions on access to the root dsn or schema dn can differ based on the administrator's preference. So besides knowing the different directory products and what they can do, you should also invest some time in getting to know the admins for the directories you'll be querying and find out how they've been configured. Phil Lembo
