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.

As a way to distribute the load for RFC1918-related queries, we use IPv4 anycast addressing. The address block is 192.175.48.0/24 and its origin AS is 112. This address block is advertised from multiple points around the Internet, and these distributed servers coordinate their responses and back end statistical analyses.