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Network Working Group M. Andrews
Internet-Draft ISC
Intended status: Best Current March 2, 2007
Practice
Expires: September 3, 2007
Locally-served DNS Zones
draft-ietf-dnsop-default-local-zones-01
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 September 3, 2007.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
Practice has shown that there are a number of DNS zones all iterative
resolvers and recursive nameservers should, unless configured
otherwise, automatically serve. RFC 4193 already 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 usage constraints.
Andrews Expires September 3, 2007 [Page 1]
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
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 3330 Zones . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Local IPv6 Unicast Addresses . . . . . . . . . . . . . . . 6
4.4. IPv6 Locally Assigned Local Addresses . . . . . . . . . . 6
4.5. IPv6 Link Local Addresses . . . . . . . . . . . . . . . . 6
5. Zones that are Out-Of-Scope . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . . 8
Appendix A. Change History [To Be Removed on Publication] . . . . 9
A.1. draft-ietf-dnsop-default-local-zones-01.txt . . . . . . . 9
A.2. draft-ietf-dnsop-default-local-zones-00.txt . . . . . . . 9
A.3. draft-andrews-full-service-resolvers-03.txt . . . . . . . 9
A.4. draft-andrews-full-service-resolvers-02.txt . . . . . . . 9
Appendix B. Proposed Status [To Be Removed on Publication] . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
Practice has shown that there are a number of DNS [RFC 1034] [RFC
1035] zones all iterative resolvers and recursive nameservers should,
unless 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 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 sacrificial name servers
have been deployed to protect the immediate parent name servers for
these zones from excessive, unintentional, query load [AS112]. 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 but drop responses for these name spaces
also puts a significant load on the root servers. They also cause
operational load for the root server operators as they have to reply
to queries about why the root servers are "attacking" these clients.
Changing the default configuration will address all these issues for
the zones listed below in Section 4.
[RFC 4193] already 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.
It 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].
2. Effects on sites using RFC 1918 addresses.
For most sites using [RFC 1918] addresses, the changes here will have
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little or no detrimental effect. If the site does not already have
the reverse tree populated the only effect will be that the answers
are 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. In either case the
local resolver has a pre-existing configuration for the namespace and
won't add the automatic zone.
The main impact will be felt at sites that make use of delegation for
reverse lookups for [RFC 1918] addresses and have populated these
zones. Typically, such sites will be fully disconnected from the
Internet and have their own root servers for their own non-Internet
DNS tree. These sites will need to override the default
configuration expressed in this document to allow resolution to
continue.
3. Changes to Iterative Resolver Behaviour.
Unless configured otherwise, an iterative resolver will now return
name errors (RCODE=3) for queries within the lists of zones covered
below, 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.
A implementation doing this MUST provide a mechanism to disable this
new behaviour, preferably 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 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 ".". Implementations SHOULD provide a
mechanism to set these values. No address records need to be
provided for the name server.
Below is a example of a generic empty zone in master file format. It
will produce a negative cache ttl of 3 hours.
@ 10800 IN SOA @ . 1 3600 1200 604800 10800
@ 10800 IN NS @
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
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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 it they are not
intended to control any zone transfer activity.
The NS RR is needed as some UPDATE clients use NS queries to discover
they zone to be updated. Having no address records for the name
server should abort UPDATE processing in the client
4. Lists Of Zones Covered
The lists below are expected to seed a IANA registry.
4.1. RFC 1918 Zones
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
4.2. RFC 3330 Zones
See [RFC 3330].
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 */
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4.3. Local IPv6 Unicast Addresses
See [RFC 4291], sections 2.4, 2.5.2 and 2.5.3.
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.IP
6.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.IP
6.ARPA
4.4. IPv6 Locally Assigned Local Addresses
See [RFC 4193].
D.F.IP6.ARPA
4.5. IPv6 Link Local Addresses
See [RFC 4291], sections 2.4 and 2.5.6.
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
Globally 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 to F.E.F.IP6.ARPA may
still need to be deployed in the short term if the traffic becomes
excessive.
For IPv6 Globally Assigned Local addresses [RFC 4291] there has been
no decision made about whether the registries 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 above. If they do, then registries
will need to take steps to ensure that name servers are provided for
these addresses.
This document is also ignoring IP6.INT. IP6.INT has been wound up
with only legacy resolvers now generating reverse queries under
IP6.INT.
This document has also deliberately ignored names immediately under
the root. While there is a subset of queries to the roots which
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could be addressed using the techniques described here (e.g. .local
and IPv4 addresses) there is also a vast amount of traffic that
requires a different strategy (e.g. lookups for unqualied hostnames,
IPv6 addresses).
6. IANA Considerations
This document recommends that IANA establish a registry of zones
which require this default behaviour, the initial contents of which
are in Section 4. More zones are expected to be added, and possibly
deleted from this registry over time. Name server 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] or IETF Review in 2434bis.
IANA should co-ordinate with the RIRs and ICANN to ensure the DNSSEC
deployment in the reverse trees that these zone are delegated in a
unsecure manner as per Security Considerations.
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 full service resolvers have been re-
configured.
When DNSSEC is deployed within the IN-ADDR.ARPA and IP6.ARPA
namespaces, the zones listed above will need to be delegated as
insecure delegations. 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 leakage of
unsigned answers from the Internet.
8. Acknowledgements
This work was supported by the US National Science Foundation
(research grant SCI-0427144) and DNS-OARC.
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9. References
9.1. Normative References
[RFC 1034]
Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES",
RFC 1034, STD 13, November 1987.
[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 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 3330]
"Special-Use IPv4 Addresses", RFC 3330, September 2002.
[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 4291]
Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
9.2. Informative References
[AS112] "AS112 Project", <http://as112.net/>.
[RFC 4193]
Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
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Addresses", RFC 4193, October 2005.
Appendix A. Change History [To Be Removed on Publication]
A.1. draft-ietf-dnsop-default-local-zones-01.txt
Revised impact description.
Updated to reflect change in IP6.INT status.
A.2. 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.3. draft-andrews-full-service-resolvers-03.txt
Added "Proposed Status".
A.4. 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
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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).
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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]
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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
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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].
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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 @
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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 |
+----------------------+
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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:
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+--------------+
| 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).
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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.
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[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.
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[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.
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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
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