Glue In DNS Referral Responses Is Not Optional
draft-ietf-dnsop-glue-is-not-optional-00

Document Type Active Internet-Draft (dnsop WG)
Last updated 2020-06-03
Replaces draft-andrews-dnsop-glue-is-not-optional
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Network Working Group                                         M. Andrews
Internet-Draft                                                       ISC
Updates: 1034 (if approved)                                 June 3, 2020
Intended status: Standards Track
Expires: December 5, 2020

             Glue In DNS Referral Responses Is Not Optional
                draft-ietf-dnsop-glue-is-not-optional-00

Abstract

   The DNS uses glue records to allow iterative clients to find the
   addresses of nameservers that live within the delegated zone.  Glue
   records are expected to be returned as part of a referral and if they
   cannot be fitted into the UDP response, TC=1 MUST be set to inform
   the client that the response is incomplete and that TCP SHOULD be
   used to retrieve the full response.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   This Internet-Draft will expire on December 5, 2020.

Copyright Notice

   Copyright (c) 2020 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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   (https://trustee.ietf.org/license-info) in effect on the date of
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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Reserved Words  . . . . . . . . . . . . . . . . . . . . .   4
   2.  Modifications to RFC1034  . . . . . . . . . . . . . . . . . .   4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The DNS [RFC1034], [RFC1035] uses glue records to allow iterative
   clients to find the addresses of nameservers that live within the
   delegated zone.  Glue records are expected to be returned as part of
   a referral and if they cannot be fitted into the UDP response, TC=1
   MUST be set to inform the client that the response is incomplete and
   that TCP SHOULD be used to retrieve the full response.

   While not common, real life examples of servers that fail to set TC=1
   when glue records are available exist and they do cause resolution
   failures.  The example below shows a case where none of the glue
   records, present in the zone, fitted into the available space and
   TC=1 was not set in the response.  While this example shows an DNSSEC
   [RFC4033], [RFC4034], [RFC4035] referral response, this behaviour has
   also been seen with plain DNS responses as well.  The records have
   been truncated for display purposes.

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   % dig +norec +dnssec +bufsize=512 +ignore @a.gov-servers.net \
           rh202ns2.355.dhhs.gov

   ; <<>> DiG 9.15.4 <<>> +norec +dnssec +bufsize +ignore \
           @a.gov-servers.net rh202ns2.355.dhhs.gov
   ; (2 servers found)
   ;; global options: +cmd
   ;; Got answer:
   ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8798
   ;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 9, ADDITIONAL: 1

   ;; OPT PSEUDOSECTION:
   ; EDNS: version: 0, flags: do; udp: 4096
   ;; QUESTION SECTION:
   ;rh202ns2.355.dhhs.gov.         IN A

   ;; AUTHORITY SECTION:
   dhhs.gov.               86400   IN NS      rh120ns2.368.dhhs.gov.
   dhhs.gov.               86400   IN NS      rh202ns2.355.dhhs.gov.
   dhhs.gov.               86400   IN NS      rh120ns1.368.dhhs.gov.
   dhhs.gov.               86400   IN NS      rh202ns1.355.dhhs.gov.
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