Dropped Remaining Other Propaganda in DNS Responses
draft-hardaker-dnsop-drop-00

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Last updated 2019-11-20
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Network Working Group                                        W. Hardaker
Internet-Draft                                                   USC/ISI
Intended status: Standards Track                       November 20, 2019
Expires: May 23, 2020

          Dropped Remaining Other Propaganda in DNS Responses
                      draft-hardaker-dnsop-drop-00

Abstract

   When DNS replies to be sent over UDP exceed the requestor's UDP
   payload size, servers are expected to set the Truncated bit (TC) and
   remove remove additional information from the response.  Clients
   receiving the TC bit might choose to retry the request over TCP to
   fetch the removed information.  Sometimes this extra information is
   not important to the DNS resolution process and retrying over TCP may
   not be needed.  This document defines the DP bit to indicate that the
   dropped information that caused the TC bit was supplemental
   information.  This is useful, for example, in the case of Extended
   DNS Error information which may be mostly debugging related
   information.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on May 23, 2020.

Copyright Notice

   Copyright (c) 2019 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

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Modifications to DNS Processing . . . . . . . . . . . . . . .   2
   3.  Applicable Use Cases  . . . . . . . . . . . . . . . . . . . .   2
     3.1.  Extended DNS Errors . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Informative References  . . . . . . . . . . . . . . . . . . .   3
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   3

1.  Introduction

   When DNS replies to be sent over UDP exceed the requestor's UDP
   payload size [EDNS0], servers are expected to set the Truncated bit
   (TC) [DOMANINAMES] and remove remove additional information from the
   response.  Clients receiving the TC bit might choose to retry the
   request over TCP to fetch the removed information.  Sometimes this
   extra information is not important to the DNS resolution process and
   retrying over TCP may not be needed.  This document defines the
   "drop" bit (DP) to indicate that the dropped information that caused
   the TC bit was supplemental information.  This is useful, for
   example, in the case of Extended DNS Error information which may be
   mostly debugging related information.

2.  Modifications to DNS Processing

   Servers returning a UDP response containing supplemental information
   (such as Extended DNS Error information (xxx: need non-RFC here))
   that caused the TC bit to be set SHOULD set the DP bit.

   Clients receiving a UDP response with both the TC bit and the DP bit
   set may choose to not resend their request over TCP since DP bit
   indicates the extra information is ignorable.

3.  Applicable Use Cases

   The removal of any other information from a DNS response that would
   set the TC bit should not set the DP bit unless a specification

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   indicates it should be set.  This specification lists the following
   scenarios where this should be set.

3.1.  Extended DNS Errors

   DNS servers setting the TC bit when EDE information was removed from
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