http://www.rfc-editor.org/rfc/rfc4848.txt
RFC 4848: Domain-Based Application Service Location Using URIs and the Dynamic Delegation Discovery Service (DDDS), L. Daigle2007-04-01T23:00:00-00:00The purpose of this document is to define a new, straightforward Dynamic Delegation Discovery Service (DDDS) application to allow mapping of domain names to URIs for particular application services and protocols. Although defined as a new DDDS application, dubbed U-NAPTR, this is effectively an extension of the Straightforward NAPTR (S-NAPTR) DDDS Application. [STANDARDS-TRACK]