format (e.g. %cc).
:custom_mapping: Defines the mapping between the lookup format and a custom value to replace ``%mp`` placeholder.
+:zones_dir: Directory to load zones from. Each file must contain exactly one ``zone:`` object, formatted like individual domains in the example configuration above.
:mapping_lookup_formats: Same as per domain, but used as default value if not defined at the domain level.
:custom_mapping: Same as per domain, but used as default value if not defined at the domain level.