Locally Served DNS Zones
RFC 6303

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Internet Engineering Task Force (IETF)                        M. Andrews
Request for Comments: 6303                                           ISC
BCP: 163                                                       July 2011
Category: Best Current Practice
ISSN: 2070-1721

                        Locally Served DNS Zones

Abstract

   Experience with the Domain Name System (DNS) has shown that there are
   a number of DNS zones that all iterative resolvers and recursive
   nameservers should automatically serve, unless configured otherwise.
   RFC 4193 specifies that this should occur for D.F.IP6.ARPA.  This
   document extends the practice to cover the IN-ADDR.ARPA zones for RFC
   1918 address space and other well-known zones with similar
   characteristics.

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 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/rfc6303.

Copyright Notice

   Copyright (c) 2011 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.

Andrews                   Best Current Practice                 [Page 1]
RFC 6303                Locally Served DNS Zones               July 2011

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................2
      1.1. Reserved Words .............................................3
   2. Effects on Sites Using RFC 1918 Addresses .......................3
   3. Changes to Iterative Resolver Behaviour .........................4
   4. Lists Of Zones Covered ..........................................5
      4.1. RFC 1918 Zones .............................................5
      4.2. RFC 5735 and RFC 5737 Zones ................................5
      4.3. Local IPv6 Unicast Addresses ...............................6
      4.4. IPv6 Locally Assigned Local Addresses ......................6
      4.5. IPv6 Link-Local Addresses ..................................7
      4.6. IPv6 Example Prefix ........................................7
   5. Zones That Are Out of Scope .....................................7
   6. IANA Considerations .............................................8
   7. Security Considerations .........................................8
   8. Acknowledgements ................................................9
   9. References ......................................................9
      9.1. Normative References .......................................9
      9.2. Informative References ....................................10

1.  Introduction

   Experience with the Domain Name System (DNS, [RFC1034] and [RFC1035])
   has shown that there are a number of DNS zones that all iterative
   resolvers and recursive nameservers SHOULD automatically serve,
   unless intentionally configured otherwise.  These zones include, but
   are not limited to, the IN-ADDR.ARPA zones for the address space
   allocated by [RFC1918] and the IP6.ARPA zones for locally assigned
   unique local IPv6 addresses defined in [RFC4193].

Andrews                   Best Current Practice                 [Page 2]
RFC 6303                Locally Served DNS Zones               July 2011

   This recommendation is made because data has shown that significant
   leakage of queries for these namespaces is occurring, despite