@ IN SOA localhost. root.localhost. ( 1997051801 ; Serial 10800 ; Refresh every 3 hours 3600 ; Retry after 1 hour 604800 ; Expire after 1 week 86400 ; Minimum TTL 1 day ) IN NS localhost. ; ; Addresses point to canonical names ; 1.0.0 IN PTR localhost. ; Loopback network name 0.0.0 IN PTR loopback-net.