The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
A resource record in a zone file contains the following fields, some of which are optional depending on the record type:
- Name
Domain name or IP address.
- TTL (time to live)
The maximum time that a name server caches a record before it checks whether a newer one is available.
- Class
Always
IN
for Internet.- Type
Type of record, for example:
-
A
(address) IPv4 address corresponding to a host.
-
AAAA
(address) IPv6 address corresponding to a host.
-
CNAME
(canonical name) Alias name corresponding to a host name.
-
MX
(mail exchange) Destination for email addressed to the domain.
-
NS
(name server) Fully qualified domain name of an authoritative name server for a domain.
-
PTR
(pointer) Host name corresponding to an IP address for address to name lookups (reverse-name resolution).
-
SOA
(start of authority) Authoritative information about a zone, such as the master name server, the email address of the domain's administrator, and the domain's serial number. All records following a
SOA
record relate to the zone that it defines up to the nextSOA
record.
-
- Data
The information that the record stores, such as an IP address in an
A
record, or a host name in aCNAME
orPTR
record.
The following example shows the contents of a typical zone file
such as /var/named/master-data
:
$TTL 86400 ; 1 day @ IN SOA dns.us.mydom.com. root.us.mydom.com. ( 57 ; serial 28800 ; refresh (8 hours) 7200 ; retry (2 hours) 2419200 ; expire (4 weeks) 86400 ; minimum (1 day) ) IN NS dns.us.mydom.com. dns IN A 192.168.2.1 us.mydom.com IN A 192.168.2.1 svr01 IN A 192.168.2.2 www IN CNAME svr01 host01 IN A 192.168.2.101 host02 IN A 192.168.2.102 host03 IN A 192.168.2.103 ...
A comment on a line is preceded by a semicolon
(;
).
The $TTL
directive defines the default
time-to-live value for all resource records in the zone. Each
resource record can define its own time-to-live value, which
overrides the global setting.
The SOA
record is mandatory and included the
following information:
-
us.mydom.com
The name of the domain.
-
dns.us.mydom.com.
The fully qualified domain name of the name server, including a trailing period (
.
) for the root domain.-
root.us.mydom.com.
The email address of the domain administrator.
-
serial
A counter that, if incremented, tells
named
to reload the zone file.-
refresh
The time after which a primary name server notifies backup name servers that they should refresh their database.
-
retry
If a refresh fails, the time that a backup name server should wait before attempting another refresh.
-
expire
The maximum elapsed time that a backup name server has to complete a refresh before its zone records are no longer considered authoritative and it will stop answering queries.
-
minimum
The minimum time for which other servers should cache information obtained from this zone.
An NS
record declares an authoritative name
server for the domain.
Each A
record specifies the IP address that
corresponds to a host name in the domain.
The CNAME
record creates the alias
www
for svr01
.
For more information, see the BIND documentation in
/usr/share/doc/bind-
.
version
/arm