; /etc/bind/zones/example.org $TTL 3h; @ IN SOA ns.example.org. example.org. ( 1 ; serial 3h; refresh timeout 1h; retry timeout 1w; expire timeout 1h; negative caching TTL ) @ IN NS ns.example.org. ; name server @ IN MX 10 example.org. ; mail exchange server ns IN A 1.2.3.4 @ IN A 1.2.3.4 ns IN AAAA ef::1 @ IN AAAA ef::1 www IN CNAME example.org.