Authoritative DNS-over-TLS Operational Considerations

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dprive or dnsop                                             K. Henderson
Internet-Draft                                                  Verisign
Intended status: Informational                                  T. April
Expires: January 21, 2020                                         Akamai
                                                            J. Livingood
                                                           July 20, 2019

         Authoritative DNS-over-TLS Operational Considerations


   DNS over TLS (DoT) has been gaining attention, primarily as a means
   of communication between stub resolvers and recursive resolvers.
   There have also been discussions and experiments involving the use of
   DoT to communicate with authoritative nameservers (Authoritative DNS
   over TLS or "ADoT"), including communication between recursive and
   authoritative resolvers.  However, we have identified a number of
   operational concerns with ADoT.  These operational concerns need to
   be addressed prior to ADoT's deployment at scale by DNS operators in
   order to maintain the stability and resilience of the global DNS.
   The document also provides some suggested next steps to advance the
   operator community's understanding of ADoT's operational impact.

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Table of Contents

   1.  Introduction
     1.1.  Background and Motivation
       1.1.1.  Why operational considerations are so important for
       1.1.2.  Other considerations related to ADoT
   2.  Terminology
     2.1.  Requirements Language
     2.2.  Definitions
   3.  Key Issues and Questions
     3.1.  Signaling Support for ADoT
     3.2.  Port number
     3.3.  TLS version
     3.4.  Resumptions
     3.5.  Operational Monitoring
     3.6.  Architecture
     3.7.  Socket efficiency/tuning considerations
     3.8.  Post-Quantum Security
   4.  Suggestions for further research and development
     4.1.  Required studies and analysis
     4.2.  Authoritative DNS over TLS (ADoT) Profile
   5.  Security Considerations
   6.  References
     6.1.  Informative References
     6.2.  URIs
   Appendix A.  Acknowledgements
   Appendix B.  Change Log
   Authors' Addresses

1.  Introduction

   This is an operational considerations document that focuses on the
   factors operators need to consider when implementing Authoritative
   DNS over TLS.  An evaluation of the merits of DNS over TLS are beyond
   the scope and intent of this document.

   Typically, DNS communication between stub resolvers, recursive
   resolvers, and authoritative servers is not encrypted.  Some argue
   that this can pose a privacy challenge for Internet users, because
   their access to named network resources can potentially be tracked
   through their DNS communication.  In principle, any network element
   along the path between the user and resolving or authoritative
   nameservers could observe this unencrypted traffic.  Many of these
   concerns are addressed in [RFC7626].

   [RFC8310] proposes using DNS over TLS (DoT) in order to encrypt DNS

   Historically, much of the work on DNS encryption has focused on the
   stub-to-recursive path as the recursive-to-authoritative server path
   does not leak user specific information.  However, with the increased
   deployment of EDNS0 Client Subnet [RFC7871], recursive-to-
   authoritative encryption is becoming an area of interest.  Therefore,
   this document focuses on the recursive-to-authoritative aspect of DoT
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