DNS Terminology
RFC 8499

Document Type RFC - Best Current Practice (January 2019; No errata)
Obsoletes RFC 7719
Updates RFC 2308
Also known as BCP 219
Last updated 2019-01-02
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Suzanne Woolf
Shepherd write-up Show (last changed 2018-07-30)
IESG IESG state RFC 8499 (Best Current Practice)
Consensus Boilerplate Yes
Telechat date
Responsible AD Warren Kumari
Send notices to Suzanne Woolf <suzworldwide@gmail.com>
IANA IANA review state IANA OK - No Actions Needed
IANA action state No IANA Actions
Internet Engineering Task Force (IETF)                        P. Hoffman
Request for Comments: 8499                                         ICANN
BCP: 219                                                     A. Sullivan
Obsoletes: 7719
Updates: 2308                                                K. Fujiwara
Category: Best Current Practice                                     JPRS
ISSN: 2070-1721                                             January 2019

                            DNS Terminology

Abstract

   The Domain Name System (DNS) is defined in literally dozens of
   different RFCs.  The terminology used by implementers and developers
   of DNS protocols, and by operators of DNS systems, has sometimes
   changed in the decades since the DNS was first defined.  This
   document gives current definitions for many of the terms used in the
   DNS in a single document.

   This document obsoletes RFC 7719 and updates RFC 2308.

Status of This Memo

   This memo documents an Internet Best Current Practice.

   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).  Further information on
   BCPs is available in 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
   https://www.rfc-editor.org/info/rfc8499.

Hoffman, et al.           Best Current Practice                 [Page 1]
RFC 8499                     DNS Terminology                January 2019

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
   (https://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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Names . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  DNS Response Codes  . . . . . . . . . . . . . . . . . . . . .  10
   4.  DNS Transactions  . . . . . . . . . . . . . . . . . . . . . .  11
   5.  Resource Records  . . . . . . . . . . . . . . . . . . . . . .  14
   6.  DNS Servers and Clients . . . . . . . . . . . . . . . . . . .  16
   7.  Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
   8.  Wildcards . . . . . . . . . . . . . . . . . . . . . . . . . .  27
   9.  Registration Model  . . . . . . . . . . . . . . . . . . . . .  28
   10. General DNSSEC  . . . . . . . . . . . . . . . . . . . . . . .  30
   11. DNSSEC States . . . . . . . . . . . . . . . . . . . . . . . .  34
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  36
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  36
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  36
     14.2.  Informative References . . . . . . . . . . . . . . . . .  39
   Appendix A.  Definitions Updated by This Document . . . . . . . .  44
   Appendix B.  Definitions First Defined in This Document . . . . .  44
   Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  50
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  50

Hoffman, et al.           Best Current Practice                 [Page 2]
RFC 8499                     DNS Terminology                January 2019

1.  Introduction

   The Domain Name System (DNS) is a simple query-response protocol
   whose messages in both directions have the same format.  (Section 2
   gives a definition of "public DNS", which is often what people mean
   when they say "the DNS".)  The protocol and message format are
   defined in [RFC1034] and [RFC1035].  These RFCs defined some terms,
   and later documents defined others.  Some of the terms from [RFC1034]
   and [RFC1035] have somewhat different meanings now than they did in
   1987.

   This document contains a collection of a wide variety of DNS-related
   terms, organized loosely by topic.  Some of them have been precisely
   defined in earlier RFCs, some have been loosely defined in earlier
   RFCs, and some are not defined in an earlier RFC at all.

   Other organizations sometimes define DNS-related terms their own way.
   For example, the WHATWG defines "domain" at
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