i am using RHEL4.

by google i come to know about automountMap as an objectClass.

and this objectClass is not bydefault defined in any schema.

plz tell me how to configure nfs and ldap.

I have three top level objects, all objectClass=nisMap:

nisMapName=auto.groups
nisMapName=auto.home
nisMapName=auto.master

Then under auto.master there are two objects with objectClass=nisObject:
cn=/home
nisMapEntry=ldap:nisMapName=auto.home,dc=example,dc=com
nisMapName=auto.master

cn=/groups
nisMapEntry=ldap:nisMapName=auto.groups,dc=example,dc=com -g

Only the home entry is "required", the other is for a mount at /groups which I was using for ... group directories.

Under nisMapName=auto.home there are all my user directory objects which all have objectClass=nisObject:

cn=/
nisMapEntry=nfsservername.com:/full/path/to/real/files/&
nisMapName=auto.home
cn=username
nisMapEntry=nfsservername.com:/full/path/to/real/files/username
nisMapName=auto.home

Where the first one is for "all users" and the / and & are wildcards for the username which doesn't match any other entries in the map. So a username "tom" would be mapped to "nfsservername.com:/full/path/to/real/files/tom" if he didn't have a separate entry.

The group objects are all children of nisMapName=auto.groups and are similar in content to the ones shown above.

I didn't put this in LDIF format and I assume you know a little about LDAP already, so if not I can expand a bit I suppose.

A nice project that makes dealing with LDAP a lot nicer is http://lam.sourceforge.net/ I liked it enough I got his commercial offering, but the open version is very helpful for administration.