http://www.rfc-editor.org/rfc/rfc4386.txt
RFC 4386: Internet X.509 Public Key Infrastructure Repository Locator Service, S. Boeyen, P. Hallam-Baker2006-02-01T23:00:00-00:00This document defines a Public Key Infrastructure (PKI) repository locator service. The service makes use of DNS SRV records defined in accordance with RFC 2782. The service enables certificate-using systems to locate PKI repositories.This memo defines an Experimental Protocol for the Internet community.