The APNIC Whois Database is used as the management database for producing the DNS zones so 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 is the reverse DNS zone under in-addr.arpa or ip6.arpa. The nserver attributes in each domain object define the officially delegated DNS name servers (the NS in DNS zone contents).
Public availability of reverse DNS zones at APNIC
For all IP address blocks IANA (the Internet Assigned Numbers Authority) allocates to APNIC, IANA also delegates corresponding reverse DNS zones within the centrally administered 'in-addr.arpa' and 'ip6.arpa' domains.
APNIC also publishes zone fragments, which are the parts of zones managed by other parties, namely:
- The other RIRs (Regional Internet Registries), which share zone management of early registration networks
- NIRs (National Internet Registries), which manage IP address space allocated to them for further distribution to their members
Access to reverse DNS data
Apart from access via conventional DNS queries, APNIC supports access to reverse DNS data in four ways:
- Whois queries, either directly to APNIC from other whois services or via the Web
- Bulk access to the APNIC Whois Database by FTP or NRTM (Near Real Time Mirroring)
- FTP access to the DNS zone files
Operational and policy restrictions are imposed on data access via each of these methods. These restrictions are in place to protect the performance of the systems being used to provide DNS services and to limit 'mining' and misuse of administrative data (such as contact records).
Access to reverse DNS data by whois query
The APNIC Whois Database is currently used as the management database for producing the DNS zones so it can provide the information for each delegated IPv4 and IPv6 range registered in the reverse DNS.
Outside the global DNS system, information regarding reverse DNS delegations can be checked via whois queries.
The information is stored as domain objects (RPSL format). The name of each domain object is the reverse DNS zone in in-addr.arpa or ip6.arpa. The nserver attributes in each domain object define the officially-delegated DNS name servers' zone contents.
Ordinary access via whois queries is subject to daily limits. Queries via the web-based whois interface are also subject to rate-based limits. These access limits apply to all whois data, not just that which is DNS-related. The actual limits set are monitored by APNIC and adjusted where appropriate.
Access to reverse DNS data by FTP
APNIC publishes the DNS zone information as text files at:
The files are published with an associated file that contains the zones' MD5 checksum and a detached PGP signature so they can be verified independently.
There are no Acceptable Use Policy (AUP) restrictions on general access to the APNIC FTP service, but APNIC reserves the right to limit the:
- Simultaneous connections
- Number of downloaded files
- Total data size downloaded per connection to limit the load on the servers and the network