Example of a DNS zone file: automationserver.com
2013080542 ;make up a number based on the date
3H ;refresh interval
2W ;expiration date
1W ; minimum until you ask server again, matches TTL
ns1 IN A 18.104.22.168
www IN A 22.214.171.124
www IN AAAA 2020::1:1
$TTL indicates a DNS node tree and the starting point of a DNS zone file and default expiration time of all resource records without their own TTL value which is 1 week in this case.
SOA record – The Start of Authority record is a required option for each zone.
– contains the name of the zone ,
– email address of the entity responsible for administering the domain’s zone file (not used here),
– current serial number of the zone,