http://www.rfc-editor.org/rfc/rfc4471.txt
RFC 4471: Derivation of DNS Name Predecessor and Successor, G. Sisson, B. Laurie2006-09-01T23:00:00-00:00This document describes two methods for deriving the canonically-ordered predecessor and successor of a DNS name. These methods may be used for dynamic NSEC resource record synthesis, enabling security-aware name servers to provide authenticated denial of existence without disclosing other owner names in a DNSSEC secured zone. This memo defines an Experimental Protocol for the Internet community.