RFC 6761, "Special-Use Domain Names", February 2013Source of RFC: IETF - NON WORKING GROUP
Errata ID: 4970
Publication Format(s) : TEXT
Reported By: Alexander Lay
Date Reported: 2017-03-15
Rejected by: Warren Kumari
Date Rejected: 2017-06-12
Section 6.1 says:
It should say:
The IP address ranges listed in this document as private do not align with those listed as private in the referenced RFC 1918.
Nope, there are in "reverse lookup" format.
The useful references are probably:
https://tools.ietf.org/html/rfc1033 Section IN-ADDR.ARPA and
https://tools.ietf.org/html/rfc6303 Section 4.1. RFC 1918 Zones.
More info (from rfc1033):
The structure of names in the domain system is set up in a
hierarchical way such that the address of a name can be found by
tracing down the domain tree contacting a server for each label of
the name. Because of this 'indexing' based on name, there is no easy
way to translate a host address back into its host name.
In order to do the reverse translation easily, a domain was created
that uses hosts' addresses as part of a name that then points to the
data for that host. In this way, there is now an 'index' to hosts'
RRs based on their address. This address mapping domain is called
IN-ADDR.ARPA. Within that domain are subdomains for each network,
based on network number. Also, for consistency and natural
groupings, the 4 octets of a host number are reversed.
For example, the ARPANET is net 10. That means there is a domain
called 10.IN-ADDR.ARPA. Within this domain there is a PTR RR at
18.104.22.168.IN-ADDR that points to the RRs for the host SRI-NIC.ARPA
(who's address is 10.0.0.51). Since the NIC is also on the MILNET
(Net 26, address 22.214.171.124), there is also a PTR RR at 126.96.36.199.IN-
ADDR.ARPA that points to the same RR's for SRI-NIC.ARPA. The format
of these special pointers is defined below along with the examples
for the NIC.
<special-name> [<ttl>] [<class>] PTR <name>
The PTR record is used to let special names point to some other
location in the domain tree. They are mainly used in the IN-
ADDR.ARPA records for translation of addresses to names. PTR's
should use official names and not aliases.
For example, host SRI-NIC.ARPA with addresses 10.0.0.51 and 188.8.131.52
would have the following records in the respective zone files for net
10 and net 26:
184.108.40.206.IN-ADDR.ARPA. PTR SRI-NIC.ARPA.
220.127.116.11.IN-ADDR.ARPA. PTR SRI-NIC.ARPA.