$TTL 2d . IN SOA ns.root. hostmaster.ns.root. ( 2 ; Serial 604800 ; Refresh 86400 ; Retry 2419200 ; Expire 604800 ) ; Nagative Cache TTL . NS ns.root. ns.root. A 10.30.20.1 $ORIGIN and. @ NS a.and. a.and. A 10.30.20.2