Validators
Record Validators
Base classes for record-level and value-level validation. Custom validators
subclass RecordValidator or
ValueValidator and are registered with
the ValidatorRegistry.
Zone Validators
Base classes and built-in implementations for zone-level validation. Custom
validators subclass ZoneValidator and are
registered via register_zone_validator().
The ZoneValidatorRegistry activates them
by set name (e.g. legacy, strict, best-practice).