


Network Working Group                                         M. Andrews
Internet-Draft                                                       ISC
Intended status: Best Current                          November 19, 2007
Practice
Expires: May 22, 2008


                        Locally-served DNS Zones
                draft-ietf-dnsop-default-local-zones-03

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on May 22, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   Experience has shown that there are a number of DNS zones all
   iterative resolvers and recursive nameservers should, unless
   configured otherwise, automatically serve.  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.




Andrews                   Expires May 22, 2008                  [Page 1]

Internet-Draft          Locally-served DNS Zones           November 2007


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Reserved Words . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Effects on sites using RFC 1918 addresses. . . . . . . . . . .  4
   3.  Changes to Iterative Resolver Behaviour. . . . . . . . . . . .  4
   4.  Lists Of Zones Covered . . . . . . . . . . . . . . . . . . . .  5
     4.1.  RFC 1918 Zones . . . . . . . . . . . . . . . . . . . . . .  5
     4.2.  RFC 3330 Zones . . . . . . . . . . . . . . . . . . . . . .  6
     4.3.  Local IPv6 Unicast Addresses . . . . . . . . . . . . . . .  6
     4.4.  IPv6 Locally Assigned Local Addresses  . . . . . . . . . .  6
     4.5.  IPv6 Link Local Addresses  . . . . . . . . . . . . . . . .  7
   5.  Zones that are Out-Of-Scope  . . . . . . . . . . . . . . . . .  7
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  8
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  8
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Change History [To Be Removed on Publication] . . . . 10
     A.1.  draft-ietf-dnsop-default-local-zones-03.txt  . . . . . . . 10
     A.2.  draft-ietf-dnsop-default-local-zones-02.txt  . . . . . . . 10
     A.3.  draft-ietf-dnsop-default-local-zones-01.txt  . . . . . . . 10
     A.4.  draft-ietf-dnsop-default-local-zones-00.txt  . . . . . . . 11
     A.5.  draft-andrews-full-service-resolvers-03.txt  . . . . . . . 11
     A.6.  draft-andrews-full-service-resolvers-02.txt  . . . . . . . 11
   Appendix B.  Proposed Status [To Be Removed on Publication]  . . . 11
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
   Intellectual Property and Copyright Statements . . . . . . . . . . 12






















Andrews                   Expires May 22, 2008                  [Page 2]

Internet-Draft          Locally-served DNS Zones           November 2007


1.  Introduction

   Experience has shown that there are a number of DNS [RFC 1034] [RFC
   1035] zones that all iterative resolvers and recursive nameservers
   SHOULD, unless intentionally configured otherwise, automatically
   serve.  These zones include, but are not limited to, the IN-ADDR.ARPA
   zones for the address space allocated by [RFC 1918] and the IP6.ARPA
   zones for locally assigned unique local IPv6 addresses, [RFC 4193].

   This recommendation is made because data has shown that significant
   leakage of queries for these name spaces is occurring, despite
   instructions to restrict them, and because it has therefore become
   necessary to deploy sacrificial name servers to protect the immediate
   parent name servers for these zones from excessive, unintentional,
   query load [AS112] [I-D.draft-ietf-dnsop-as112-ops]
   [I-D.draft-ietf-dnsop-as112-under-attack-help-help].  There is every
   expectation that the query load will continue to increase unless
   steps are taken as outlined here.

   Additionally, queries from clients behind badly configured firewalls
   that allow outgoing queries for these name spaces but drop the
   responses, put a significant load on the root servers (forward but no
   reverse zones configured).  They also cause operational load for the
   root server operators as they have to reply to enquiries about why
   the root servers are "attacking" these clients.  Changing the default
   configuration will address all these issues for the zones listed in
   Section 4.

   [RFC 4193] recommends that queries for D.F.IP6.ARPA be handled
   locally.  This document extends the recommendation to cover the IN-
   ADDR.ARPA zones for [RFC 1918] and other well known IN-ADDR.ARPA and
   IP6.ARPA zones for which queries should not appear on the public
   Internet.

   It is hoped that by doing this the number of sacrificial servers
   [AS112] will not have to be increased, and may in time be reduced.

   This recommendation should also help DNS responsiveness for sites
   which are using [RFC 1918] addresses but do not follow the last
   paragraph in Section 3 of [RFC 1918].

1.1.  Reserved Words

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC 2119].





Andrews                   Expires May 22, 2008                  [Page 3]

Internet-Draft          Locally-served DNS Zones           November 2007


2.  Effects on sites using RFC 1918 addresses.

   For most sites using [RFC 1918] addresses, the changes here will have
   little or no detrimental effect.  If the site does not already have
   the reverse tree populated the only effect will be that the name
   error responses will be generated locally rather than remotely.

   For sites that do have the reverse tree populated, most will either
   have a local copy of the zones or will be forwarding the queries to
   servers which have local copies of the zone.  Therefore this
   recommendation will not be relevant.

   The most significant impact will be felt at sites that make use of
   delegations for [RFC 1918] addresses and have populated these zones.
   These sites will need to override the default configuration expressed
   in this document to allow resolution to continue.  Typically, such
   sites will be fully disconnected from the Internet and have their own
   root servers for their own non-Internet DNS tree.


3.  Changes to Iterative Resolver Behaviour.

   Unless configured otherwise, an iterative resolver will now return
   authoritatively (aa=1) name errors (RCODE=3) for queries within the
   zones in Section 4, with the obvious exception of queries for the
   zone name itself where SOA, NS and "no data" responses will be
   returned as appropriate to the query type.  One common way to do this
   is to serve empty (SOA and NS only) zones.

   An implementation of this recommendation MUST provide a mechanism to
   disable this new behaviour, and SHOULD allow this decision on a zone
   by zone basis.

   If using empty zones one SHOULD NOT use the same NS and SOA records
   as used on the public Internet servers as that will make it harder to
   detect the origin of the responses and thus any leakage to the public
   Internet servers.  This document recommends that the NS record
   defaults to the name of the zone and the SOA MNAME defaults to the
   name of the only NS RR's target.  The SOA RNAME should default to
   "nobody.invalid."  [RFC 2606].  Implementations SHOULD provide a
   mechanism to set these values.  No address records need to be
   provided for the name server.

   Below is an example of a generic empty zone in master file format.
   It will produce a negative cache TTL of 3 hours.

   @ 10800 IN SOA @ nobody.invalid. 1 3600 1200 604800 10800 @ 10800
   IN NS @



Andrews                   Expires May 22, 2008                  [Page 4]

Internet-Draft          Locally-served DNS Zones           November 2007


   The SOA RR is needed to support negative caching [RFC 2308] of name
   error responses and to point clients to the primary master for DNS
   dynamic updates.

   SOA values of particular importance are the MNAME, the SOA RR's TTL
   and the negTTL value.  Both TTL values SHOULD match.  The rest of the
   SOA timer values MAY be chosen arbitrarily since they are not
   intended to control any zone transfer activity.

   The NS RR is needed as some UPDATE clients use NS queries to discover
   the zone to be updated.  Having no address records for the name
   server is expected to abort UPDATE [RFC 2136] processing in the
   client.


4.  Lists Of Zones Covered

   The following subsections are intended to seed the IANA registry as
   requested in the IANA Considerations Section.  The zone name is the
   entity to be registered.

4.1.  RFC 1918 Zones

   The following zones correspond to the IPv4 address space reserved in
   [RFC 1918].

                         +----------------------+
                         | Zone                 |
                         +----------------------+
                         | 10.IN-ADDR.ARPA      |
                         | 16.172.IN-ADDR.ARPA  |
                         | 17.172.IN-ADDR.ARPA  |
                         | 18.172.IN-ADDR.ARPA  |
                         | 19.172.IN-ADDR.ARPA  |
                         | 20.172.IN-ADDR.ARPA  |
                         | 21.172.IN-ADDR.ARPA  |
                         | 22.172.IN-ADDR.ARPA  |
                         | 23.172.IN-ADDR.ARPA  |
                         | 24.172.IN-ADDR.ARPA  |
                         | 25.172.IN-ADDR.ARPA  |
                         | 26.172.IN-ADDR.ARPA  |
                         | 27.172.IN-ADDR.ARPA  |
                         | 28.172.IN-ADDR.ARPA  |
                         | 29.172.IN-ADDR.ARPA  |
                         | 30.172.IN-ADDR.ARPA  |
                         | 31.172.IN-ADDR.ARPA  |
                         | 168.192.IN-ADDR.ARPA |
                         +----------------------+



Andrews                   Expires May 22, 2008                  [Page 5]

Internet-Draft          Locally-served DNS Zones           November 2007


4.2.  RFC 3330 Zones

   The following zones correspond to those address ranges from [RFC
   3330] that are not expected to appear as source or destination
   addresses on the public Internet and to not have a unique name to
   associate with.

   The recommendation to serve an empty zone 127.IN-ADDR.ARPA is not a
   attempt to discourage any practice to provide a PTR RR for
   1.0.0.127.IN-ADDR.ARPA locally.  In fact, a meaningful reverse
   mapping should exist, but the exact setup is out of the scope of this
   document.  Similar logic applies to the reverse mapping for ::1
   Section 4.3.  The recommendations made here simply assume no other
   coverage for these domains exists.

         +------------------------------+------------------------+
         | Zone                         | Description            |
         +------------------------------+------------------------+
         | 0.IN-ADDR.ARPA               | IPv4 "THIS" NETWORK    |
         | 127.IN-ADDR.ARPA             | IPv4 LOOP-BACK NETWORK |
         | 254.169.IN-ADDR.ARPA         | IPv4 LINK LOCAL        |
         | 2.0.192.IN-ADDR.ARPA         | IPv4 TEST NET          |
         | 255.255.255.255.IN-ADDR.ARPA | IPv4 BROADCAST         |
         +------------------------------+------------------------+

4.3.  Local IPv6 Unicast Addresses

   The reverse mappings ([RFC 3596], Section 2.5 IP6.ARPA Domain) for
   the IPv6 Unspecified (::) and Loopback (::1) addresses ([RFC 4291],
   Sections 2.4, 2.5.2 and 2.5.3) are covered by these two zones:

               +-------------------------------------------+
               | Zone                                      |
               +-------------------------------------------+
               | 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.\ |
               | 0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA          |
               | 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.\ |
               | 0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA          |
               +-------------------------------------------+

   Note: Line breaks and a escapes '\' have been inserted above for
   readability and to adhere to line width constraints.  They are not
   parts of the zone names.

4.4.  IPv6 Locally Assigned Local Addresses

   Section 4.4 of [RFC 4193] already required special treatment of:




Andrews                   Expires May 22, 2008                  [Page 6]

Internet-Draft          Locally-served DNS Zones           November 2007


                             +--------------+
                             | Zone         |
                             +--------------+
                             | D.F.IP6.ARPA |
                             +--------------+

4.5.  IPv6 Link Local Addresses

   IPv6 Link-Local Addresses as of [RFC 4291], Section 2.5.6 are covered
   by four distinct reverse DNS zones:

                            +----------------+
                            | Zone           |
                            +----------------+
                            | 8.E.F.IP6.ARPA |
                            | 9.E.F.IP6.ARPA |
                            | A.E.F.IP6.ARPA |
                            | B.E.F.IP6.ARPA |
                            +----------------+


5.  Zones that are Out-Of-Scope

   IPv6 site-local addresses, [RFC 4291] Sections 2.4 and 2.57, and IPv6
   Centrally Assigned Local [RFC 4193] addresses are not covered here.
   It is expected that IPv6 site-local addresses will be self correcting
   as IPv6 implementations remove support for site-local addresses.
   However, sacrificial servers for C.E.F.IP6.ARPA through
   F.E.F.IP6.ARPA may still need to be deployed in the short term if the
   traffic becomes excessive.

   For IPv6 Centrally Assigned Local addresses (L = 0) [RFC 4193], there
   has been no decision made about whether the Regional Internet
   Registries (RIRs) will provide delegations in this space or not.  If
   they don't, then C.F.IP6.ARPA will need to be added to the list in
   Section 4.4.  If they do, then registries will need to take steps to
   ensure that name servers are provided for these addresses.

   This document also ignores IP6.INT.  IP6.INT has been wound up with
   only legacy resolvers now generating reverse queries under IP6.INT
   [RFC 4159].

   This document has also deliberately ignored names immediately under
   the root domain.  While there is a subset of queries to the root name
   servers which could be addressed using the techniques described here
   (e.g. .local, .workgroup and IPv4 addresses), there is also a vast
   amount of traffic that requires a different strategy (e.g. lookups
   for unqualified hostnames, IPv6 addresses).



Andrews                   Expires May 22, 2008                  [Page 7]

Internet-Draft          Locally-served DNS Zones           November 2007


6.  IANA Considerations

   This document requests that IANA establish a registry of zones which
   require this default behaviour.  The initial contents of which are in
   Section 4.  Implementors are encouraged to check this registry and
   adjust their implementations to reflect changes therein.

   This registry can be amended through "IETF Consensus" as per [RFC
   2434].

   IANA should co-ordinate with the RIRs to ensure that, as DNSSEC is
   deployed in the reverse tree, delegations for these zones are made in
   the manner described in Section 7.


7.  Security Considerations

   During the initial deployment phase, particularly where [RFC 1918]
   addresses are in use, there may be some clients that unexpectedly
   receive a name error rather than a PTR record.  This may cause some
   service disruption until their recursive name server(s) have been re-
   configured.

   As DNSSEC is deployed within the IN-ADDR.ARPA and IP6.ARPA
   namespaces, the zones listed above will need to be delegated as
   insecure delegations, or be within insecure zones.  This will allow
   DNSSEC validation to succeed for queries in these spaces despite not
   being answered from the delegated servers.

   It is recommended that sites actively using these namespaces secure
   them using DNSSEC [RFC 4035] by publishing and using DNSSEC trust
   anchors.  This will protect the clients from accidental import of
   unsigned responses from the Internet.


8.  Acknowledgements

   This work was supported by the US National Science Foundation
   (research grant SCI-0427144) and DNS-OARC.


9.  References

9.1.  Normative References

   [RFC 1034]
              Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES",
              RFC 1034, STD 13, November 1987.



Andrews                   Expires May 22, 2008                  [Page 8]

Internet-Draft          Locally-served DNS Zones           November 2007


   [RFC 1035]
              Mockapetris, P., "DOMAIN NAMES - IMPLEMENTATION AND
              SPECIFICATION", RFC 1035, STD 13, November 1987.

   [RFC 1918]
              Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
              and E. Lear, "Address Allocation for Private Internets",
              RFC 1918, February 1996.

   [RFC 2119]
              Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC 2136]
              Vixie, P., Thomson, A., Rekhter, Y., and J. Bound,
              "Dynamic Updates in the Domain Name System (DNS UPDATE)",
              RFC 2136, April 1997.

   [RFC 2308]
              Andrews, M., "Negative Caching of DNS Queries (DNS
              NCACHE)", RFC 2398, March 1998.

   [RFC 2434]
              Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [RFC 2606]
              Eastlake, D. and A. Panitz, "Reserved Top Level DNS
              Names", BCP 32, RFC 2606, June 1999.

   [RFC 3596]
              Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
              "DNS Extensions to Support IPv6", RFC 3596, October 2003.

   [RFC 4035]
              Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC 4159]
              Huston, G., "Deprecation of "ip6.int"", BCP 109, RFC 4159,
              August 2005.

   [RFC 4193]
              Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.




Andrews                   Expires May 22, 2008                  [Page 9]

Internet-Draft          Locally-served DNS Zones           November 2007


   [RFC 4291]
              Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

9.2.  Informative References

   [AS112]    "AS112 Project", <http://www.as112.net/>.

   [I-D.draft-ietf-dnsop-as112-ops]
              Abley, J. and W. Maton, "AS112 Nameserver Operations",
              draft-ietf-dnsop-as112-ops-00 (work in progress),
              February 2007.

   [I-D.draft-ietf-dnsop-as112-under-attack-help-help]
              Abley, J. and W. Maton, "I'm Being Attacked by
              PRISONER.IANA.ORG!",
              draft-ietf-dnsop-as112-under-attack-help-help-00 (work in
              progress), February 2007.

   [RFC 3330]
              "Special-Use IPv4 Addresses", RFC 3330, September 2002.


Appendix A.  Change History [To Be Removed on Publication]

A.1.  draft-ietf-dnsop-default-local-zones-03.txt

   expanded section 4 descriptions

   Added references [RFC 2136], [RFC 3596],
   [I-D.draft-ietf-dnsop-as112-ops] and
   [I-D.draft-ietf-dnsop-as112-under-attack-help-help].

   Revised language.

A.2.  draft-ietf-dnsop-default-local-zones-02.txt

   RNAME now "nobody.invalid."

   Revised language.

A.3.  draft-ietf-dnsop-default-local-zones-01.txt

   Revised impact description.

   Updated to reflect change in IP6.INT status.





Andrews                   Expires May 22, 2008                 [Page 10]

Internet-Draft          Locally-served DNS Zones           November 2007


A.4.  draft-ietf-dnsop-default-local-zones-00.txt

   Adopted by DNSOP.

   "Author's Note" re-titled "Zones that are Out-Of-Scope"

   Add note that these zone are expected to seed the IANA registry.

   Title changed.

A.5.  draft-andrews-full-service-resolvers-03.txt

   Added "Proposed Status".

A.6.  draft-andrews-full-service-resolvers-02.txt

   Added 0.IN-ADDR.ARPA.


Appendix B.  Proposed Status [To Be Removed on Publication]

   This Internet-Draft is being submitted for eventual publication as an
   RFC with a proposed status of Best Current Practice.


Author's Address

   Mark P. Andrews
   Internet Systems Consortium
   950 Charter Street
   Redwood City, CA  94063
   US

   Email: Mark_Andrews@isc.org

















Andrews                   Expires May 22, 2008                 [Page 11]

Internet-Draft          Locally-served DNS Zones           November 2007


Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





Andrews                   Expires May 22, 2008                 [Page 12]

