Because most answers generated by the Internet's root name server system are negative, and many of those negative answers are in response to PTR queries for RFC1918, dynamic DNS updates and other ambiguous addresses, as follows:

• 10.0.0.0/8
  
• 172.16.0.0/12
  
• 169.254.0.0/16
  
• 192.168.0.0/16
  

There are now separate (non-root) servers for these queries, described below.

Server operators are volunteers who offer a route to the well known addresses of
the AS112 servers, either to handle the queries generated by their local user
populations, or to help carry the global traffic load. We intend the list of
operators shown below to be complete and accurate, but that may not be possible.
The F root server operator also runs instances of AS112 servers at certain
sites. Some of these sites are listed here too.

This list will usually be updated once every month, unless an email is sent
to 112 -at- root-servers.org to notify us of a new node. Additionally, updates
are based on queries made to a select number of known route servers, some of
which are listed at Traceroute.org.

As a result, this list is really a best efforts endeavour, as
the final list at time of writing is not by any means either definitive or
complete.

A new mailing list for AS112 operators is now open. For subscription information, please go to the list website and follow the instructions.

Some papers have been written on the subject of Private DNS updates and reverse lookups for RFC 1918 space. Here are a few links:

The Windows of Private DNS Updates

CAIDA paper

Is Your Caching Resolver Polluting the Internet?

SIGCOMM'04 Workshops

An example using Quagga and BIND9 will be written up shortly.

Joe Abley and William F. Maton Sotomayor have submitted two Internet Drafts to the IETF for dnsops consideration. More at IETF and slides are here. The ID Tracker has a direct pointer to these.