Client Subnet in DNS Queries
RFC 7871
Internet Engineering Task Force (IETF) C. Contavalli
Request for Comments: 7871 W. van der Gaast
Category: Informational Google
ISSN: 2070-1721 D. Lawrence
Akamai Technologies
W. Kumari
Google
May 2016
Client Subnet in DNS Queries
Abstract
This document describes an Extension Mechanisms for DNS (EDNS0)
option that is in active use to carry information about the network
that originated a DNS query and the network for which the subsequent
response can be cached. Since it has some known operational and
privacy shortcomings, a revision will be worked through the IETF for
improvement.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
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 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/rfc7871.
Contavalli, et al. Informational [Page 1]
RFC 7871 Client Subnet in DNS Queries May 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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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RFC 7871 Client Subnet in DNS Queries May 2016
Table of Contents
1. Introduction ....................................................4
2. Privacy Note ....................................................5
3. Requirements Notation ...........................................5
4. Terminology .....................................................6
5. Overview ........................................................7
6. Option Format ...................................................8
7. Protocol Description ............................................9
7.1. Originating the Option .....................................9
7.1.1. Recursive Resolvers .................................9
7.1.2. Stub Resolvers .....................................10
7.1.3. Forwarding Resolvers ...............................11
7.2. Generating a Response .....................................11
7.2.1. Authoritative Nameserver ...........................11
7.2.2. Intermediate Nameserver ............................13
7.3. Handling ECS Responses and Caching ........................14
7.3.1. Caching the Response ...............................15
7.3.2. Answering from Cache ...............................16
7.4. Delegations and Negative Answers ..........................17
7.5. Transitivity ..............................................18
8. IANA Considerations ............................................18
9. DNSSEC Considerations ..........................................19
10. NAT Considerations ............................................19
11. Security Considerations .......................................20
11.1. Privacy ..................................................20
11.2. Birthday Attacks .........................................21
11.3. Cache Pollution ..........................................22
12. Sending the Option ............................................23
12.1. Probing ..................................................23
12.2. Whitelist ................................................24
13. Example .......................................................24
14. References ....................................................26
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