Clarifications and Implementation Notes for DNS Security (DNSSEC)
RFC 6840
Internet Engineering Task Force (IETF) S. Weiler, Ed.
Request for Comments: 6840 SPARTA, Inc.
Updates: 4033, 4034, 4035, 5155 D. Blacka, Ed.
Category: Standards Track Verisign, Inc.
ISSN: 2070-1721 February 2013
Clarifications and Implementation Notes for DNS Security (DNSSEC)
Abstract
This document is a collection of technical clarifications to the DNS
Security (DNSSEC) document set. It is meant to serve as a resource
to implementors as well as a collection of DNSSEC errata that existed
at the time of writing.
This document updates the core DNSSEC documents (RFC 4033, RFC 4034,
and RFC 4035) as well as the NSEC3 specification (RFC 5155). It also
defines NSEC3 and SHA-2 (RFC 4509 and RFC 5702) as core parts of the
DNSSEC specification.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6840.
Weiler & Blacka Standards Track [Page 1]
RFC 6840 DNSSEC Implementation Notes February 2013
Copyright Notice
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Without obtaining an adequate license from the person(s) controlling
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outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Weiler & Blacka Standards Track [Page 2]
RFC 6840 DNSSEC Implementation Notes February 2013
Table of Contents
1. Introduction and Terminology ....................................4
1.1. Structure of This Document .................................4
1.2. Terminology ................................................4
2. Important Additions to DNSSEC ...................................4
2.1. NSEC3 Support ..............................................4
2.2. SHA-2 Support ..............................................5
3. Scaling Concerns ................................................5
3.1. Implement a BAD Cache ......................................5
4. Security Concerns ...............................................5
4.1. Clarifications on Nonexistence Proofs ......................5
4.2. Validating Responses to an ANY Query .......................6
4.3. Check for CNAME ............................................6
4.4. Insecure Delegation Proofs .................................7
5. Interoperability Concerns .......................................7
5.1. Errors in Canonical Form Type Code List ....................7
5.2. Unknown DS Message Digest Algorithms .......................7
5.3. Private Algorithms .........................................8
5.4. Caution about Local Policy and Multiple RRSIGs .............9
5.5. Key Tag Calculation ........................................9
5.6. Setting the DO Bit on Replies ..............................9
5.7. Setting the AD Bit on Queries .............................10
5.8. Setting the AD Bit on Replies .............................10
5.9. Always Set the CD Bit on Queries ..........................10
5.10. Nested Trust Anchors .....................................11
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