Chapter 17. Supported record types and their storage

This chapter lists all record types PDNS supports, and how they are stored in backends. The list is mostly alphabetical but some types are grouped.

A

The A record contains an IP address. It is stored as a decimal dotted quad string, for example: '213.244.168.210'.

AAAA

The AAAA record contains an IPv6 address. An example: '3ffe:8114:2000:bf0::1'.

CNAME

The CNAME record specifies the canonical name of a record. It is stored plainly. Like all other records, it is not terminated by a dot. A sample might be 'webserver-01.yourcompany.com'.

HINFO

Hardware Info record, used to specify CPU and operating system. Stored with a single space separating these two, example: 'i386 Linux'.

MX

The MX record specifies a mail exchanger host for a domain. Each mail exchanger also has a priority or preference. This should be specified in the separate field dedicated for that purpose, often called 'prio'.

NAPTR

Naming Authority Pointer, RFC 2915. Stored as follows:

	      '100  50  "s"  "z3950+I2L+I2C"     ""  _z3950._tcp.gatech.edu'. 
	      
The fields are: order, preference, flags, service, regex, replacement. Note that the replacement is not enclosed in quotes, and should not be. The replacement may be omitted, in which case it is empty. See also RFC 2916 for how to use NAPTR for ENUM (E.164) purposes.

NS

Nameserver record. Specifies nameservers for a domain. Stored plainly: 'ns1.powerdns.com', as always without a terminating dot.

PTR

Reverse pointer, used to specify the host name belonging to an IP or IPv6 address. Name is stored plainly: 'www.powerdns.com'. As always, no terminating dot.

RP

Responsible Person record, as described in RFC 1183. Stored with a single space between the mailbox name and the more-information pointer. Example 'peter.powerdns.com peter.people.powerdns.com', to indicate that peter@powerdns.com is responsible and that more information about peter is available by querying the TXT record of peter.people.powerdns.com.

SOA

The Start of Authority record is one of the most complex available. It specifies a lot about a domain: the name of the master nameserver ('the primary'), the hostmaster and a set of numbers indicating how the data in this domain expires and how often it needs to be checked. Further more, it contains a serial number which should rise on each change of the domain.

The stored format is:

		primary hostmaster serial refresh retry expire default_ttl
	      
Besides the primary and the hostmaster, all fields are numerical. PDNS has a set of default values:

Table 17-1. SOA fields

primarydefault-soa-name configuration option
hostmasterhostmaster@domain-name
serial0
refresh10800 (3 hours)
retry3600 (1 hour)
expire604800 (1 week)
default_ttl3600 (1 hour)

The fields have complicated and sometimes controversial meanings. The 'serial' field is special. If left at 0, the default, PDNS will perform an internal list of the domain to determine highest change_date field of all records within the zone, and use that as the zone serial number. This means that the serial number is always raised when changes are made to the zone, as long as the change_date field is being set.

SRV

SRV records can be used to encode the location and port of services on a domain name. When encoding, the priority field is used to encode the priority. For example, '_ldap._tcp.dc._msdcs.conaxis.ch SRV 0 100 389 mars.conaxis.ch' would be encoded with 0 in the priority field and '100 389 mars.conaxis.ch' in the content field.

TXT

The TXT field can be used to attach textual data to a domain. Text is stored plainly.