I am confusing
 

Hai LQ friends
I am practicing openldap-2.3 in RHEL5 box. I am confusing with this words "schema" "modules". What is schema and what is modules?

Have you looked at the documentation regarding LDAP in general? Google for "ldap tutorial"

http://coewww.rutgers.edu/www1/linux.../lecture8.html

The schema is how things are laid out in LDAP (context, organizational unit, etc.). Modules are what plug-ins you have, such as PAM modules, NIS modules, etc.

LDAP
 

To deploy LDAP in a server, do I need to install PAM and NIS first? or LPDA works without them.

thanks

A very short answer (in rough terms):

A module is a program called to do something - it may be a password program, database backend, or similar.

A schema is like a database field definition (but more than that).

Have a look at slapd.conf for an idea of some of the module options that are common, and in /etc/openldap/schema for some of the schema files and what they contain.