CHAIN Query Requests in DNS
RFC 7901
Internet Engineering Task Force (IETF) P. Wouters
Request for Comments: 7901 Red Hat
Category: Experimental June 2016
ISSN: 2070-1721
CHAIN Query Requests in DNS
Abstract
This document defines an EDNS0 extension that can be used by a
security-aware validating resolver configured to use a forwarding
resolver to send a single query, requesting a complete validation
path along with the regular query answer. The reduction in queries
potentially lowers the latency and reduces the need to send multiple
queries at once. This extension mandates the use of source-IP-
verified transport such as TCP or UDP with EDNS-COOKIE, so it cannot
be abused in amplification attacks.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation.
This document defines an Experimental Protocol for the Internet
community. 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). Not
all documents approved by the IESG are a candidate for any level of
Internet Standard; see Section 2 of RFC 7841.
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/rfc7901.
Wouters Experimental [Page 1]
RFC 7901 CHAIN Query Requests in DNS June 2016
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Option Format . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Protocol Description . . . . . . . . . . . . . . . . . . . . 6
5.1. Discovery of Support . . . . . . . . . . . . . . . . . . 6
5.2. Generate a Query . . . . . . . . . . . . . . . . . . . . 6
5.3. Send the Option . . . . . . . . . . . . . . . . . . . . . 6
5.4. Generate a Response . . . . . . . . . . . . . . . . . . . 7
6. Protocol Considerations . . . . . . . . . . . . . . . . . . . 8
6.1. DNSSEC Considerations . . . . . . . . . . . . . . . . . . 8
6.2. NS Record Considerations . . . . . . . . . . . . . . . . 8
6.3. Session Management . . . . . . . . . . . . . . . . . . . 9
6.4. Negative Trust Anchors . . . . . . . . . . . . . . . . . 9
6.5. Anycast Considerations . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7.1. Additional Work and Bandwidth . . . . . . . . . . . . . . 10
7.2. Amplification Attacks . . . . . . . . . . . . . . . . . . 10
7.3. Privacy Considerations . . . . . . . . . . . . . . . . . 10
8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. CHAIN Query for "www.example.com" . . . . . . . . . . . . 10
8.2. Out-of-Path Query for "example.com" . . . . . . . . . . . 12
8.3. Nonexistent Data . . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9.1. EDNS0 Option Code for CHAIN . . . . . . . . . . . . . . . 14
10. Normative References . . . . . . . . . . . . . . . . . . . . 14
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16
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RFC 7901 CHAIN Query Requests in DNS June 2016
1. Introduction
Traditionally, a DNS client operates in stub mode. For each DNS
question the DNS client needs to resolve, it sends a single query to
an upstream recursive resolver to obtain a single DNS answer. When
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