In order to use the user and group mappings stored in an LDAP directory, which setting in smb.conf is correct?

This syntax is incomplete as it lacks the initial `ldap:` prefix, which is necessary to explicitly specify the type of `idmap` backend being used.

The correct `smb.conf` syntax for configuring the `idmap backend` to use LDAP, including the LDAP server URI, is `idmap backend = ldap:ldap://ldap.example.com:636`. The first 'ldap' specifies the backend type, and 'ldap://ldap.example.com:636' provides the specific server address and port for the LDAP directory.

This syntax uses `ldap server =`, which is not the correct parameter for specifying the LDAP server within the `idmap backend` directive; the server URI should be part of the `idmap backend` value itself.

This option only specifies the backend type as `ldap` but does not include the essential LDAP server address and port, rendering it incomplete for practical use with an external LDAP directory.