RFC 3655 (rfc3655) - Page 1 of 8

Redefinition of DNS Authenticated Data (AD) bit

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Network Working Group                                      B. Wellington
Request for Comments: 3655                                O. Gudmundsson
Updates: 2535                                              November 2003
Category: Standards Track


            Redefinition of DNS Authenticated Data (AD) bit

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document alters the specification defined in RFC 2535.  Based on
   implementation experience, the Authenticated Data (AD) bit in the DNS
   header is not useful.  This document redefines the AD bit such that
   it is only set if all answers or records proving that no answers
   exist in the response has been cryptographically verified or
   otherwise meets the server's local security policy.

1.  Introduction

   Familiarity with the DNS system [RFC 1035] and DNS security extensions
   [RFC 2535] is helpful but not necessary.

   As specified in RFC 2535 (section 6.1), the AD (Authenticated Data)
   bit indicates in a response that all data included in the answer and
   authority sections of the response have been authenticated by the
   server according to the policies of that server.  This is not
   especially useful in practice, since a conformant server SHOULD never
   reply with data that failed its security policy.

   This document redefines the AD bit such that it is only set if all
   data in the response has been cryptographically verified or otherwise
   meets the server's local security policy.  Thus, neither a response
   containing properly delegated insecure data, nor a server configured
   without DNSSEC keys, will have the AD set.  As before, data that
   failed to verify will not be returned.  An application running on a
   host that has a trust relationship with the server performing the



Wellington & Gudmundsson    Standards Track
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