primary ~on_update ~timer ~port stack primary starts a primary server on port (default 53, both TCP and UDP) with the given primary configuration. timer is the DNS notify timer in seconds, and defaults to 2 seconds. on_update ~old ~authenticated_key ~update_source s is a callback if the data served by the primary server s got updated by a potentially authenticated nsupdate packet, the used authenticated_key and source update_source are passed to the callback. The on_notify notify s callback is executed when a notify request is received by the primary DNS server (may be used for signaling of a (hidden) DNS secondary server).

secondary ~on_update ~timer ~port stack secondary starts a secondary server on port (default 53). The on_update callback is executed when the zone changes. The timer (in seconds, defaults to 5 seconds) is used for refreshing zones.