DNS_DOMAIN_ALREADY_EXISTS
HTTP 409No
Domain (zone) is already registered with the DNS provider — it exists in another account or is under a registry/zone hold, so it cannot be bound here. param=domain.
By default a failed call returns a result with an error instead of throwing, so your business flow is never interrupted.
Published error codes are permanent: their meaning never silently changes, and deprecated codes keep returning for at least 12 months.