http://www.rfc-editor.org/rfc/rfc5855.txt
RFC 5855: Nameservers for IPv4 and IPv6 Reverse Zones, J. Abley, T. Manderson2010-05-01T23:00:00-00:00This document specifies a stable naming scheme for the nameservers that serve the zones IN-ADDR.ARPA and IP6.ARPA in the DNS. These zones contain data that facilitate reverse mapping (address to name). This memo documents an Internet Best Current Practice.