The AS112 project is a group of volunteer name server operators joined in an autonomous system

Autonomous system (Internet)

Within the Internet, an Autonomous System is a collection of connected Internet Protocol routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet....

. They run anycast

Anycast

Anycast is a network addressing and routing methodology in which datagrams from a single sender are routed to the topologically nearest node in a group of potential receivers all identified by the same destination address.-Addressing methodologies:...

ed instances of the name servers that answer reverse DNS lookup

Reverse DNS lookup

In computer networking, reverse DNS lookup or reverse DNS resolution is the determination of a domain name that is associated with a given IP address using the Domain Name System of the Internet....

s for private network

Private network

In the Internet addressing architecture, a private network is a network that uses private IP address space, following the standards set by RFC 1918 and RFC 4193. These addresses are commonly used for home, office, and enterprise local area networks , when globally routable addresses are not...

 and link-local

Link-local address

A link-local address is an Internet Protocol address that is intended only for communications within the segment of a local network or a point-to-point connection that a host is connected to. Routers do not forward packets with link-local addresses....

 addresses sent to the public Internet. These queries ambiguous by their nature, and can not be answered correctly. But negative answers are provided anyway to reduce the load on the public DNS infrastructure.

History

Before 2001, the in-addr.arpa zones for the RFC 1918 networks were delegated to a single instance of name servers, blackhole-1.iana.org and blackhole-2.iana.org, called the blackhole server

Blackhole server

Blackhole DNS servers are DNS servers that return a "nonexistent address" answer to reverse DNS lookups for addresses reserved for private use.-Background:...

s. The IANA

Internet Assigned Numbers Authority

The Internet Assigned Numbers Authority is the entity that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System , media types, and other Internet Protocol-related symbols and numbers...

-run servers were under increasing load from improperly-configured NAT networks, leaking out reverse DNS queries, also causing unnecessary load on the root servers. The decision was made by a small subset of root server operators to run the reverse delegations using a model as described in RFC 3258; each announcing the network using the autonomous system number of 112. Later the group of volunteers has grown to include many other organizations.

Answered zones

The name servers participating in the AS112 project are each configured to answer authoritatively for the following zones:

• For the 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 private networks (RFC 1918):
  • 10.in-addr.arpa
  • 16.172.in-addr.arpa
  • 17.172.in-addr.arpa
  • 18.172.in-addr.arpa
  • 19.172.in-addr.arpa
  • 20.172.in-addr.arpa
  • 21.172.in-addr.arpa
  • 22.172.in-addr.arpa
  • 23.172.in-addr.arpa
  • 24.172.in-addr.arpa
  • 25.172.in-addr.arpa
  • 26.172.in-addr.arpa
  • 27.172.in-addr.arpa
  • 28.172.in-addr.arpa
  • 29.172.in-addr.arpa
  • 30.172.in-addr.arpa
  • 31.172.in-addr.arpa
  • 168.192.in-addr.arpa
• For the 169.254.0.0/16 link-local network (RFC 3927)
  • 254.169.in-addr.arpa
• For unique identification purposes:
  • hostname.as112.net

External sources

• AS112 web page
• RSSAC Meeting Atlanta 2002 Notes describing RFC 1918 network queries impact on the Root servers.
• Mailing list for AS112 operators.
• RFC 6304 - AS112 Nameserver Operations
• RFC 6305 - I'm Being Attacked by PRISONER.IANA.ORG!