Any type of LDAP service, whether it is an actual server or a gateway to other LDAP services, is called an LDAP server.
You can specify multiple directory services for high-availability failover protection. Not every directory service in the list needs to be an LDAP server.
For example:
[DIRECTORY]
ldap=libsybdldap.dll ldap://seashore/dc=sybase,dc=com??one??bindname=uid=Manager,dc=sybase, dc=com?password
In this example, if the connection to test:389 fails, the connection fails over to the DCE driver with the specified DIT base. If this also fails, a connection to the LDAP server on huey:11389 is attempted. Different vendors employ different DIT base formats.
For more information, see the Open Client
Client-Library/C Programmer’s Guide and
the Open Client Client-Library/C Reference Manual 