Where does drupal store LDAP server information?
By default Drupal doesn't store any LDAP server information.
If anything is stored by other modules, it's stored in the database.
Depending on different modules, these data is saved in different tables.

If you're using LDAP module for Drupal 7, you can find the settings in ldap_servers table.

If you're using LDAP module for Drupal 6, you can find the settings in ldapauth table.