name {ttl} addr-class SOA Source Person-in-charge
@ IN SOA ucbvax.Berkeley.EDU kjd.ucbvax.Berkeley.EDU.
(
1994021501;Serial
10800 ;Refresh
3600 ;Retry
3600000 ;Expire
86400 ;Minimum
)
The Start of Authority record, SOA, designates the start of a zone. There should be only one SOA record per zone. The name is the name of the zone. It can be a complete domain name like "Berkeley.EDU." or a name relative to the current $ORIGIN. The "at" sign (@) indicates the current zone name, taken from the "primary" line in the named.boot file or from a previous $ORIGIN line.
Source is the name of the host on which the master data file resides, typically the primary master server.
Person-in-charge is the mailing address for the person responsible for the name server. The mailing address is encoded in the form of a domain name where the "at" sign (@) separating the user name from the hostname is replaced with a period. In the example above, kjd.ucbvax.berkeley.edu is the encoded form of kjd@ucbvax.berkeley.edu.
Serial is the version number of this data file, and should be incremented whenever data are changed. Do not use floating point numbers (numbers with a decimal point, such as 1.1). A useful convention is to encode the current date in the serial number. For example, 25 April 1994 edit #1 is encoded as:
Increment the edit number if you modify the file more than once on a given day.1994042501
Refresh indicates how often, in seconds, a secondary name server is to check with the primary name server to see if an update is needed.
Retry indicates how long, in seconds, a secondary server is to retry after a failure to check for a refresh.
Expire is the maximum number of seconds that a secondary name server has to use the data before they expire for lack of getting a refresh.
Minimum is the default number of seconds to be used for the time-to-live field on resource records with no explicit time-to-live value.