named.soa(4tcp)

named.soa -- file containing SOA and NS records for a zone

Synopsis

name [ttl] class SOA origin person_in_charge (
serial_number
refresh_time
retry_time
expiry_time
time_to_live )
[ttl] class NS nameserver

Description

A named.soa file is a convenient way of storing the start of authority (SOA) and name server (NS) records for a single zone on a primary server. The SOA record designates the start of a zone. The zone ends at the next SOA record. The information in named.soa is included in the named.hosts(4tcp), named.local(4tcp), and named.rev(4tcp) zone files using the $INCLUDE directive at the start of the file.

The filename is arbitrary.

For more information on the fields of SOA and NS records, see named.hosts(4tcp).

The SOA lists a serial number, which should be changed each time the master file is changed. Note that the serial number can be given as a dotted number, but this is unwise since the translation to normal integers uses concatenation rather than multiplication and addition. You can catenate the year, month, day of month, and a version number in the range 0-99 and still fit inside the unsigned 32-bit size of this field.

Secondary servers check the serial number at intervals specified by the refresh time in seconds; if the serial number changes, a zone transfer will be done to load the new data. If a master server cannot be contacted when a refresh is due, the retry time specifies the interval at which refreshes should be attempted. If a master server cannot be contacted within the interval given by the expire time, all data from the zone is discarded by secondary servers.

NOTE: From BIND 8.2.1, the minimum time-to-live value is applied to negative responses. It is no longer the default minimum time-to-live value for resource records that do not specify a ttl value, unless there is no preceding $TTL in Administering TCP/IP and Internet services statement. In this case, a warning is generated.

Files

/etc/inet/named.d/named.soa

References

named(1Mtcp), named.boot(4tcp), named.hosts(4tcp), named.local(4tcp), named.rev(4tcp), root.cache(4tcp)

RFC 1035, RFC 2308

Examples

The following example named.soa entries show a zone with primary name server volga and secondary name server istanbul, and which is administered by dave@mynet.com.

@	IN SOA	volga.mynet.COM. dave.mynet.COM (
		1993091901	; Serial number
		10880		; Refresh time
		1800		; Retry time
		3600000		; Expiry time
		259200	)	; Minimum time-to-live
	IN NS	volga.mynet.COM
	IN NS	istanbul.mynet.COM