[designate] How to avoid NXDOMAIN or stale data during cold start of a (new) machine

Hello openstack-discuss, I have a designate setup using bind9 as the user-serving DNS server. When starting a machine with either very old or no zones at all, NXDOMAIN or other actually stale data is sent out to clients as designate is not done doing an initial full sync / reconciliation. * What is the "proper" way to tackle this cold-start issue and to keep the bind from serving wrong data? ** Did I miss on any options to handle this startup case? * What is the usual runtime for an initial sync that you observe in case the backend DNS server has no zones at all anymore? Regards Christian