The SOA record designates the start of a zone
and must appear at the beginning of every DNS
hosts file.
An SOA record includes the following fields:
``Name''
Name of the zone.
``Origin''
Name of the host on which this data file resides.
``Person in charge''
Mailing address for the person responsible for the name server.
``Serial number''
Version number of this data file;
this number should be incremented whenever a change is made to the data.
The use of a decimal point in the serial number is not recommended.
``Refresh''
How often, in seconds, a secondary name server
is to check with the primary name server to see if an update is needed.
``Retry''
How long, in seconds, a secondary server should wait before retrying
a failed zone transfer.
``Expire''
Upper time limit, in seconds, that a secondary name server
is to use the data before it expires for lack of getting a refresh.
``Minimum''
Default number of seconds to be used for the time-to-live
field on resource records that do not specify one in the zone file.
There should only be one SOA record per zone.
Here is an example of an SOA record:
name {ttl} addr-class SOA Origin Person in charge
@ IN SOA volga.mynet.COM. dave.mynet.COM (
1993041403 ; Serial
3600 ; Refresh
300 ; Retry
3600000 ; Expire
259200) ; Minimum