Toshiba E-STUDIO190F Service Manual page 267

9.5.4. SOA (Start of Authority) Record
Each database file starts with a Start of Authority (SOA) record for the file. This record specifies the zone's
primary server, the server that maintains the read/write copy of the file. The syntax of this record is as
follows:
IN SOA <source host><contact email><serial No.><refresh time><retry time><expiration time><TTL>
An example of the syntax is shown below:
;
; File:
; Purpose: This file establishes the identity of this DNS.
;
;
;
;
@ IN SOA
;
IN NS
1 IN PTR
;
SOA Record (Bind 4.9.5 for NT) in "db.127.0.0" file
The "@" symbol in this example indicates the local server; "IN" indicates an Internet record. The FQDN for
the name server NWR18 must end in a period. Note that the email address for the administrator must have
a period instead of the "@" symbol. Also, if the SOA record is on more than one line, an open parenthesis
must end the first line, and a close parenthesis must end the last line.
The following list explains the other parameters:
* Source host: The name of the host that has the read/write copy of the zone file.
* Contact email: The Internet email address of the person who maintains this file. This address must be
expressed with a period instead of the "@" that is usually found in email addresses (i.e.
hostmaster.rdmg.mgcs.mei.co.jp instead of hostmaster@rdmg.mgcs.mei.co.jp).
* Serial number: A version number for the zone file. This number should be changed each time the zone
file changes, it changes automatically if you use DNS Manager to change the zone file.
* Refresh time: The time, in seconds, that a secondary server waits before checking the master server for
changes to the database file. If the file has changed, the secondary server requests a zone transfer.
* Retry time: The time, in seconds, that a secondary server waits before trying again if a zone transfer fails.
* Expiration time: The time, in seconds, that a secondary server keeps trying to transfer a zone. After the
expiration time passes, the old zone information is deleted.
* TTL: The time, in seconds, that a server can cache resource records from this database file. The TTL is
sent as part of the response for any queries that are answered from this database file. An individual
resource record can have a TT: that overrides this value.
db.127.0.0 file
SOA stands for 'start of authority' and sets the
default parameters for information this DNS is
authorized for:
nwr42.rdmg.pcc.co.jp. hostmaster.rdmg.pcc.co.jp. (
951213 ; serial number
43200 ; refresh every 12 hours
7200 ; retry after 2 hours
; expire after 2 weeks
1209600
; default ttl is 2 days
172800)
nwr42.rdmg.pcc.co.jp.
localhost.rdmg.pcc.co.jp.
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