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Reverse Delegation

The RIPE NCC registers only reverse delegations and is not involved in the registration of forward domains.

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 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 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).

Access to Reverse DNS Data via RIPEstat

The return value includes a list of domain objects as found in the RIPE Database that indicate delegation of reverse zones. Please note that the data is not processed in real time; there can be a delay of up to 24 hours.