 What
is Reverse Delegation?
The Domain Name System (DNS) is a globally distributed Internet
service. It provides name-to-number (forward) and number-to-name
(reverse) translations, using defined client-server and server-server
protocols. The DNS is a public service - any Internet user is freely
able to query the DNS system for forward or reverse translations.
Reverse DNS delegations allow applications to map to a domain name
from an IP address. Reverse delegation is achieved by use of the
special domain names in-addr.arpa (IPv4) and ip6.arpa (IPv6).
For all IP address blocks that the IANA
allocates to the RIPE NCC, they also delegate the corresponding
reverse DNS zones within the centrally-administered 'in-addr.arpa'
and 'ip6.arpa' zones.
The RIPE NCC also publishes 'zone fragments'. These are the parts
of zones managed by other parties - the other Regional Internet
Registries (RIRs), who share zone management of early registration
networks.
Access to Reverse DNS Data by Whois Query
Outside the global DNS system, you can access information about
reverse DNS delegations by whois
queries.
The RIPE Whois Database is used as
the management database for producing the DNS zones. It can provide
the information for each delegated IPv4 and IPv6 range registered
in the reverse DNS.
The information is stored in RPSL format as domain
objects. The name of each domain object is the
reverse DNS zone under in-addr.arpa or ip6.arpa. The "nserver:"
attributes in each domain object define the officially
delegated DNS nameservers (the NS in DNS zone contents).
We updated this page on:
16 March 2009
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