question about pam_ldap

[carl.huang [?建?] <carl.huang@mic.com.tw>]

Hello,
 
I'm new to openldap. I setup a ldap server. I use
pam_ldap in client  machine for user to login.

I have a question:
In client machine, from /var/log/messages: 
Nov 20 14:39:08 hjf login[3939]: pam_ldap: error trying to bind as user
"uid=hjf,ou=People,dc=padl,dc=com" (Invalid credentials).

I'm puzzling about 'ou=People'  because i don't find it in /etc/ldap.conf or
pam_ldap.so in client machine.

so how does pam_ldap determines 'ou=People'?

Thanks.
carl