named.rev(4tcp)

named.rev -- IN-ADDR.ARPA database file

Synopsis

$INCLUDE named.soa [comment]
[$ORIGIN domain [comment]]
[$TTL default_ttl [comment]]
[$GENERATE range lhs type rhs [comment] ...

name [ttl] class PTR real_name.

Description

The named.rev file contains the zone database for the IN-ADDR.ARPA domain. The actual filename is arbitrary; it is normally specified in named.boot as the source file for each IN-ADDR.ARPA domain.

Pointer records (PTR) are needed to convert IP addresses to hostnames, for example using gethostbyaddr(3N). See named.hosts(4tcp) for a description of these records.

The entries are:

name: The IP address of the host in reverse order. Only enough octets need to be specified to make the name unique within the zone.
real_name: The name of the host to which the index points. There should be an entry for each host listed in the named.hosts(4tcp) file. A trailing ``.'' prevents DNS from appending the current $ORIGIN.

See named.local(4tcp) for a description of the PTR and A records that are needed for the local loopback interface, localhost.

Generated resource records

The $GENERATE statement is used to generate a set of resource records that only differ from each other by the value of the iterator. This mechanism can be used to generate the records that are required to support reverse delegations for subnets with a mask length greater than 24 bits (described in RFC 2317).

range: Defines the iteration values using the format start-stop[/step] with 1 as the default step value. stop must be greater than start, and all must be positive integers.
lhs: Evaluates to a domain name for the record. Single ``$'' characters are replaced by the value of the iterator. A ``$'' itself may be represented by ``$$''. If lhs is not absolute (that is, it does not end in a ``.''), the current $ORIGIN is appended to the name.
type: One of CNAME, NS or PTR.
rhs: Evaluates to a domain name in a similar way to lhs.

Files

/etc/inet/named.d/db.reverse_address: suggested name for reverse hosts database file

References

gethostbyaddr(3N), named(1Mtcp), named.boot(4tcp), named.hosts(4tcp), named.local(4tcp), named.soa(4tcp), root.cache(4tcp)

RFC 1035, RFC 2317

Examples

$INCLUDE named.soa

1.130 IN PTR host1.company.COM. 2.130 IN PTR host2.company.COM. 3.130 IN PTR host3.company.COM.

The following entries perform classless IN-ADDR.ARPA delegation as described in RFC 2317:

$ORIGIN 0.0.192.IN-ADDR-ARPA.
$GENERATE 1-2 0 NS SERVER$.MYDOM.COM.
$GENERATE 1-127 $ CNAME $.0

This is equivalent to:

0.0.0.192.IN-ADDR-ARPA. NS SERVER1.MYDOM.COM.
0.0.0.192.IN-ADDR-ARPA. NS SERVER2.MYDOM.COM.
1.0.0.192.IN-ADDR-ARPA. CNAME 1.0.0.0.192.IN-ADDR-ARPA.
2.0.0.192.IN-ADDR-ARPA. CNAME 2.0.0.0.192.IN-ADDR-ARPA.
...
127.0.0.192.IN-ADDR-ARPA. CNAME 127.0.0.0.192.IN-ADDR-ARPA.