draft-ietf-dnsop-sutld-ps-00.txt   draft-ietf-dnsop-sutld-ps-01.txt 
Network Working Group T. Lemon Network Working Group T. Lemon
Internet-Draft Nominum, Inc. Internet-Draft Nominum, Inc.
Intended status: Informational R. Droms Intended status: Informational R. Droms
Expires: May 3, 2017 Expires: July 31, 2017
W. Kumari W. Kumari
Google Google
October 30, 2016 January 27, 2017
Special-Use Names Problem Statement Special-Use Names Problem Statement
draft-ietf-dnsop-sutld-ps-00 draft-ietf-dnsop-sutld-ps-01
Abstract Abstract
The Special-Use Domain Names IANA registry policy defined in RFC 6761 The Special-Use Domain Names IANA registry policy defined in RFC 6761
has been shown through experience to present unanticipated has been shown through experience to present unanticipated
challenges. This memo presents a list, intended to be comprehensive, challenges. This memo presents a list, intended to be comprehensive,
of the problems that have been identified. In addition it reviews of the problems that have been identified. In addition it reviews
the history of Domain Names and summarizes current IETF publications the history of Domain Names and summarizes current IETF publications
and some publications from other standards organizations relating to and some publications from other standards organizations relating to
special-use domain names. special-use Domain Names.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 3, 2017. This Internet-Draft will expire on July 31, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problems associated with Special-Use Domain Names . . . . . . 3 3. Problems associated with Special-Use Domain Names . . . . . . 3
4. Existing Practice Regarding SUDNs . . . . . . . . . . . . . . 7 4. Existing Practice Regarding SUDNs . . . . . . . . . . . . . . 7
4.1. Primary SUDN Documents . . . . . . . . . . . . . . . . . 7 4.1. Primary SUDN Documents . . . . . . . . . . . . . . . . . 7
4.1.1. IAB Technical Comment on the Unique DNS Root . . . . 7 4.1.1. IAB Technical Comment on the Unique DNS Root . . . . 8
4.1.2. Special-Use Domain Names . . . . . . . . . . . . . . 8 4.1.2. Special-Use Domain Names . . . . . . . . . . . . . . 9
4.1.3. MoU Concerning the Technical Work of the IANA . . . . 10 4.1.3. MoU Concerning the Technical Work of the IANA . . . . 10
4.2. Secondary documents relating to the SUTLDN question . . . 11 4.2. Secondary documents relating to the SUTLDN question . . . 11
4.2.1. Multicast DNS . . . . . . . . . . . . . . . . . . . . 11 4.2.1. Multicast DNS . . . . . . . . . . . . . . . . . . . . 11
4.2.2. The .onion Special-Use TLD . . . . . . . . . . . . . 11 4.2.2. The .onion Special-Use TLD . . . . . . . . . . . . . 12
4.2.3. Locally Served DNS Zones . . . . . . . . . . . . . . 12 4.2.3. Locally Served DNS Zones . . . . . . . . . . . . . . 12
4.2.4. Name Collision in the DNS . . . . . . . . . . . . . . 12 4.2.4. Name Collision in the DNS . . . . . . . . . . . . . . 13
4.2.5. Discovery of the IPv6 Prefix Used for IPv6 Address 4.2.5. SSAC Advisory on the Stability of the Domain
Synthesis . . . . . . . . . . . . . . . . . . . . . . 12 Namespace . . . . . . . . . . . . . . . . . . . . . . 13
4.2.6. Additional Reserved Top Level Domains . . . . . . . . 13 4.2.6. Discovery of the IPv6 Prefix Used for IPv6 Address
4.3. Summary . . . . . . . . . . . . . . . . . . . . . . . . . 13 Synthesis . . . . . . . . . . . . . . . . . . . . . . 13
5. History . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2.7. Additional Reserved Top Level Domains . . . . . . . . 13
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3. Summary . . . . . . . . . . . . . . . . . . . . . . . . . 14
7. Informative References . . . . . . . . . . . . . . . . . . . 15 5. History . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Appendix A. Change Log. . . . . . . . . . . . . . . . . . . . . 18 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 7. Informative References . . . . . . . . . . . . . . . . . . . 16
Appendix A. Change Log. . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
One of the key services required to use the Internet is name One of the key services required to use the Internet is name
resolution. Name resolution is the process of translating a symbolic resolution. Name resolution is the process of translating a symbolic
name into some object or set of objects to which the name refers, name into some object or set of objects to which the name refers,
most typically one or more IP addresses. These names are often most typically one or more IP addresses. These names are often
referred to as domain names. When reading this document, care must referred to as Domain Names. When reading this document, care must
be taken to not assume that the term Domain Name implies the be taken to not assume that the term Domain Name implies the
particular protocol for resolving these names, the Domain Name System particular protocol for resolving these names, the Domain Name System
[RFC1034]. An excellent presentation on this topic can be found in [RFC1034]. An excellent presentation on this topic can be found in
Domain Names [I-D.lewis-domain-names]. Domain Names [I-D.lewis-domain-names].
Special-Use Domain Names [RFC6761] created an IANA registry for Special-Use Domain Names [RFC6761] created an IANA registry for
special-use domain names [SDO-IANA-SUDR], defined policies for adding special-use Domain Names [SDO-IANA-SUDR], defined policies for adding
to the registry, and made some suggestions about how that policy to the registry, and made some suggestions about how that policy
might be implemented. Since the publication of RFC 6761, the IETF might be implemented. Since the publication of RFC 6761, the IETF
has been asked to designate several new special-use Domain Names in has been asked to designate several new special-use Domain Names in
this registry. During the evaluation process for these special-use this registry. During the evaluation process for these special-use
Domain Names, the IETF encountered several different sorts of issues. Domain Names, the IETF encountered several different sorts of issues.
Because of this, the IETF has decided to investigate the problem and Because of this, the IETF has decided to investigate the problem and
decide if and how the RFC 6761 process can be improved, or whether it decide if and how the RFC 6761 process can be improved, or whether it
should be deprecated. should be deprecated.
This document presents a list, believed to be complete, of the This document presents a list, believed to be complete, of the
problems associated with the assignment of special-use names. In problems associated with the assignment of special-use names. In
support of the particular set of problems described here, the support of the particular set of problems described here, the
document also includes documentation of existing practice as it document also includes documentation of existing practice as it
relates to the use of Domain Names, as well as a brief history of relates to the use of Domain Names, as well as a brief history of
domain names, and finally to describe the set of problems that exist Domain Names, and finally to describe the set of problems that exist
as reported by various IETF participants with experience in the as reported by various IETF participants with experience in the
various aspects of the problem. various aspects of the problem.
2. Terminology 2. Terminology
For the sake of brevity this document uses a number of abbreviations. For the sake of brevity this document uses a number of abbreviations.
These are expanded here: These are expanded here:
Domain Name A name which serves as input to a name resolution Domain Name A name which serves as input to a name resolution
process, for example 'EXAMPLE.ORG'. process, for example 'EXAMPLE.ORG'.
Domain Namespace The set of all possible Domain Names.
SUDN Special Use Domain Name SUDN Special Use Domain Name
SUTLDN Special-Use Top-Level Domain Name SUTLDN Special-Use Top-Level Domain Name
IANA Internet Assigned Numbers Authority IANA Internet Assigned Numbers Authority
ICANN Internet Corporation for Assigned Names and Numbers ICANN Internet Corporation for Assigned Names and Numbers
3. Problems associated with Special-Use Domain Names 3. Problems associated with Special-Use Domain Names
This section presents a list of problems that have been identified This section presents a list of problems that have been identified
with respect to the assignment of special-use names. Solutions to with respect to the assignment of special-use names. Solutions to
these problems are out of scope for this document. Because of that, these problems are out of scope for this document, and will be
problems with solutions to these problems are also out of scope for discussed in separate documents.
this document, and will be covered in a separate document.
No assertion is made that any of these problems is more or less No assertion is made that any of these problems is more or less
important than any other. The point of this is simply to enumerate important than any other. The point of this is simply to enumerate
and briefly describe the problems that have been raised during and briefly describe the problems that have been raised during
discussions of the special-use name problem. The degree of detail is discussions of the special-use name problem. The degree of detail is
intended to be sufficient that that participants in the discussion intended to be sufficient that that participants in the discussion
can agree that the problems they've raised have been adequately can agree that the problems they've raised have been adequately
described, and no more. These problems should not appear to every described, and no more. These problems should not appear to every
reader to all be problems: we intend to cover any problem that any reader to all be problems: we intend to cover any problem that any
participant considers a problem, not just those problems that participant considers a problem, not just those problems that
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In addition, no assertion is made that all of these problems must be In addition, no assertion is made that all of these problems must be
addressed, or that, if we think they should be addressed, the IETF is addressed, or that, if we think they should be addressed, the IETF is
the organization with competence to address them. While each problem the organization with competence to address them. While each problem
has one or more solutions, the solutions may in some cases be has one or more solutions, the solutions may in some cases be
mutually contradictory, or may come with costs that do not justify mutually contradictory, or may come with costs that do not justify
the benefit that would be obtained from solving them. the benefit that would be obtained from solving them.
This is the list of problems: This is the list of problems:
o ICANN is responsible for managing the public DNS root, which is o There are several different types of names in the root of the
the root from which all DNS protocol resolution starts. At the Domain Namespace:
same time, IETF has authority to reserve domain names for
technical purposes, including domain names that would otherwise be
included in the public root. No formal coordination process
exists. This complicates the coordination particularly of
assignments of single-label (top-level) special-use domain names.
o The term "technical use" in the MoU is considered by some to be * Reserved by the IETF for technical purposes
too inclusive.
o The IETF and ICANN have administrative authority over some parts * Assigned by ICANN to the public DNS root
of the domain name namespace. Not all developers of protocols on
the internet agree that this authority should reside with the IETF * ICANN Reserved Names; names that may not be applied for as a
and ICANN. TLD (see [SDO-ICANN-DAG]Section 2.2.1.2.1, Reserved Names )
* Commandeered for use by other organizations
* Not a member of any other category
o Both ICANN and the IETF have the authority and formal processes to
assign names from the pool of unused names, but no formal
coordination process exists. The lack of coordination complicates
the management of the root of the Domain Namespace and may lead to
conflicts in name assignments [SDO-ICANN-SAC090].
o The term "technical use" in RFC 2860 [RFC2860] is considered by
some to be too inclusive.
o The IETF and ICANN each have administrative authority over the
Domain Namespace. Not all developers of protocols on the internet
agree that this authority should reside with the IETF and ICANN.
o Although IETF and ICANN nominally have authority over this o Although IETF and ICANN nominally have authority over this
namespace, neither organization can enforce that authority over namespace, neither organization can enforce that authority over
any third party who wants to just start using a subset of the any third party who wants to just start using a subset of the
namespace. namespace.
o Organizations do in fact sometimes commandeer subsets of the o Organizations do in fact sometimes commandeer subsets of the
namespace. Reasons a third party might do this include: namespace. Reasons a third party might do this include:
* Unaware that a process exists for assigning such names * Unaware that a process exists for assigning such names
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* Intended use is covered by some IETF process, but don't want to * Intended use is covered by some IETF process, but don't want to
follow process follow process
* Intended use is covered by ICANN or IETF process, but expected * Intended use is covered by ICANN or IETF process, but expected
outcome is refusal or non-action outcome is refusal or non-action
o There is demand for more than one name resolution protocol for o There is demand for more than one name resolution protocol for
Domain Names, but Domain Names contain no metadata to indicate Domain Names, but Domain Names contain no metadata to indicate
which protocol to use to resolve them. which protocol to use to resolve them.
o When a special-use domain name is added to the special-use domain o When a special-use Domain Name is added to the special-use Domain
names registry, not all software that processes such names will Names registry, not all software that processes such names will
understand the special use of that name. Consequently, any such understand the special use of that name. In many cases, name
use will result in queries for that name being sent to resolution software will use the Domain Name System for resolution
authoritative servers. This constitutes an operational problem of names not known to have a special use. Consequently, any such
for operators of root zone authoritative name servers. use will result in queries for special-use names being sent to
Domain Name System authoritative servers. These queries may
constitute an operational problem for operators of root zone
authoritative name servers.
o The RFC6761 process is sufficiently uncertain that some protocol o The RFC6761 process is sufficiently uncertain that some protocol
developers have assumed they could not get a name assigned; the developers have assumed they could not get a name assigned; the
process of assigning the first new name ('.local') using the RFC process of assigning the first new name ('.local') using the RFC
6761 process took more than ten years from beginning to end: 6761 process took more than ten years from beginning to end:
longer by a factor of ten than any other part of the protocol longer by a factor of ten than any other part of the protocol
development process. Other uses of the process have proceeded development process. Other uses of the process have proceeded
more smoothly, but there is a reasonably justified perception that more smoothly, but there is a reasonably justified perception that
using this process is likely to be slow and difficult, with an using this process is likely to be slow and difficult, with an
uncertain outcome. uncertain outcome.
o There is strong resistance within the IETF to assigning names to o There is strong resistance within the IETF to assigning Domain
things outside of the DNS, for a variety of reasons: Names to resolution systems outside of the DNS, for a variety of
reasons:
* Requires a mechanism for identifying which of a set of * Requires a mechanism for identifying which of a set of
resolution processes is required in order to resolve a resolution processes is required in order to resolve a
particular name. particular name.
* Assertion of authority: there is a sense that the namespace is * Assertion of authority: there is a sense that the Domain
"owned" by the IETF or by ICANN, and so, if a name is claimed Namespace is "owned" by the IETF or by ICANN, and so, if a name
outside of that process, the person or entity that claimed that is claimed outside of that process, the person or entity that
name should suffer some consequence that would, presumably, claimed that name should suffer some consequence that would,
deter future circumvention of the official process. presumably, deter future circumvention of the official process.
* More than one name resolution protocol is bad, in the sense * More than one name resolution protocol is bad, in the sense
that a single protocol is less complicated to implement and that a single protocol is less complicated to implement and
deploy. deploy.
* The semantics of alternative resolution protocols may differ * The semantics of alternative resolution protocols may differ
from the DNS protocol; DNS has the concept of RRtypes; other from the DNS protocol; DNS has the concept of RRtypes; other
protocols may not support RRtypes, or may support some entirely protocols may not support RRtypes, or may support some entirely
different data structuring mechanism. different data structuring mechanism.
* If there is an IETF process through which a name can be * If there is an IETF process through which a name can be
assigned at zero cost other than time, this process will be assigned at zero cost other than time, this process will be
used as an alternative to purchasing the name through ICANN. used as an alternative to purchasing the name through ICANN.
* Some names that might be assigned would be sufficiently generic * The semantics associated with a particular name at the time of
that other legitimate uses of those names would overlap with a its assignment might conflict with other possible semantics and
proposed use, so that assigning the name would preclude some preclude assignment of the name to a better use in the future.
future, better use of it.
* If the IETF assigns a name that some third party or parties * If the IETF assigns a name that some third party or parties
believes belongs to them in some way, the IETF could become believes belongs to them in some way, the IETF could become
embroiled in an expensive dispute with those parties. embroiled in an expensive dispute with those parties.
o If there were no process for assigning names for technical use o If there were no process for assigning names for technical use
through the IETF, there is a concern that protocols that require through the IETF, there is a concern that protocols that require
such names would not be able to get them. such names would not be able to get them.
o In cases where the IETF has made assignments through the RFC 6761 o In cases where the IETF has made assignments through the RFC 6761
process, technical mistakes have been made due either to process, technical mistakes have been made due either to
misunderstandings as to the actual process that RFC 6761 specifies misunderstandings as to the actual process that RFC 6761 specifies
(e.g., treating the list of suggested considerations for assigning (e.g., treating the list of suggested considerations for assigning
a name as a set of requirements all of which must be met), or to a a name as a set of requirements all of which must be met), or to a
failure to follow the process that was defined in RFC 6761. failure to follow the process that was defined in RFC 6761.
o In principle, the RFC 6761 process could be used to document the o In principle, the RFC 6761 process could be used to document the
existence of domain names that are not safe to assign, and provide existence of Domain Names that are not safe to assign, and provide
information on how those names are used in practice. However, information on how those names are used in practice. However,
attempts to use RFC6761 to accomplish this attempts to use RFC6761 to accomplish this
[I-D.chapin-additional-reserved-tlds] have not been successful. [I-D.chapin-additional-reserved-tlds] have not been successful.
One side effect of this is that any mitigation effect on the root One side effect of this is that any mitigation effect on the root
name servers has been missed. name servers has been missed.
o There are several Domain Name TLDs that have been commandeered
without due process for a variety of purposes [SDO-ICANN-COLL].
The status of these names need to be clarified and recorded to
avoid future disputes about their use. [ Ed note: We note that
DNSOP has previously discussed some of these in draft-chapin-
additional-reserved-tlds-02, and decided not to adopt the draft -
https://www.ietf.org/mail-archive/web/dnsop/current/msg14887.html
. The authors are not recommending that DNSOP revisit this,
rather that is needs to be addressed in some venue. ]
o No mechanism exists for adding a name to the registry without o No mechanism exists for adding a name to the registry without
claiming that the IETF is responsible for that name, nor is it claiming that the IETF is responsible for that name, nor is it
possible to state a precedence for the name, e.g. "if ICANN possible to state a precedence for the name, e.g. "if ICANN
delegates this name, ICANN's delegation takes precedence." delegates this name, ICANN's delegation takes precedence."
o No process exists for checking documents to make sure they don't o No process exists for checking documents to make sure they don't
accidentally assign names (e.g. RFC 7788). accidentally assign names (e.g. RFC 7788).
o Use of the registry is inconsistent--some SUTLDN RFCs specify o Use of the registry is inconsistent--some SUTLDN RFCs specify
registry entries, some don't; some specify delegation, some don't. registry entries, some don't; some specify delegation, some don't.
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o The Internet requires a globally unique namespace o The Internet requires a globally unique namespace
o Private networks may operate private namespaces, but still require o Private networks may operate private namespaces, but still require
that names in the public namespace be globally unique. that names in the public namespace be globally unique.
o The Domain Name System [RFC1035] is not the only protocol that may o The Domain Name System [RFC1035] is not the only protocol that may
be used for resolving domain names. be used for resolving domain names.
o Users cannot be assumed to know how to distinguish between o Users cannot be assumed to know how to distinguish between
symbolic references that have local meaning and referebces that symbolic references that have local meaning and references that
have global meaning. Users may therefore share references that have global meaning. Users may therefore share references that
incorporate domain names with no global meaning (for example, a incorporate Domain Names with no global meaning (for example, a
URL of 'http://mysite.example.corp', where 'example.corp' is a URL of 'http://mysite.example.corp', where 'example.corp' is a
domain used privately and informally as described in domain used privately and informally as described in
[SDO-ICANN-COLL]). [SDO-ICANN-COLL]).
o Such references might refer to the object the user intends to o Such references might refer to the object the user intends to
share within that user's context, but either refer to some other share within that user's context, but either refer to some other
object any recipient's context, or might not refer to any object object any recipient's context, or might not refer to any object
at all in a recipient's context. The effect of this is that the at all in a recipient's context. The effect of this is that the
user's intended communication will not be able to be understood by user's intended communication will not be able to be understood by
the recipients of the communication. the recipients of the communication.
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o This same problem can also occur simply because a single user o This same problem can also occur simply because a single user
copies a name from one context in which it has one meaning, into a copies a name from one context in which it has one meaning, into a
different context in which it has a different meaning-- for different context in which it has a different meaning-- for
example copying a '.onion' Domain Name out of a TOR browser, where example copying a '.onion' Domain Name out of a TOR browser, where
it has meaning, and pasting this name into an ssh client that it has meaning, and pasting this name into an ssh client that
doesn't support connecting over TOR. doesn't support connecting over TOR.
To boil this down even further, we can take the following advice from To boil this down even further, we can take the following advice from
this document: this document:
o Domain names with unambiguous global meaning are preferable to o Domain Names with unambiguous global meaning are preferable to
domain names with local meaning which will be ambiguous. Domain Names with local meaning which will be ambiguous.
Nevertheless both globally-meaningful and locally-special names Nevertheless both globally-meaningful and locally-special names
are in use and must be supported. are in use and must be supported.
o At the time of the writing of this document the IAB was of the o At the time of the writing of this document the IAB was of the
opinion that there might well be more than one name resolution opinion that there might well be more than one name resolution
protocol used to resolve domain names. protocol used to resolve Domain Names.
4.1.2. Special-Use Domain Names 4.1.2. Special-Use Domain Names
The second important document is Special-Use Domain Names [RFC6761]. The second important document is "Special-Use Domain Names"
RFC6761 represents the current IETF consensus on designating and [RFC6761]. RFC6761 represents the current IETF consensus on
recording SUDNs. The IETF has experienced problems with the designating and recording SUDNs. The IETF has experienced problems
designation process described in RFC6761; these concerns motivate with the designation process described in RFC6761; these concerns
this document. Again, familiarity with RFC6761 is a prerequisite for motivate this document. Again, familiarity with RFC6761 is a
having an informed opinion on the topic of SUDNs. prerequisite for having an informed opinion on the topic of SUDNs.
RFC 6761 defines two aspects of SUDNs: designating a domain name to RFC 6761 defines two aspects of SUDNs: designating a Domain Name to
have a special purpose and registering that special use in the have a special purpose and registering that special use in the
Special-Use Domain Names registry. The designation process is Special-Use Domain Names registry. The designation process is
defined in a single sentence (RFC6761, section 4): defined in a single sentence (RFC6761, section 4):
If it is determined that special handling of a name is required in If it is determined that special handling of a name is required in
order to implement some desired new functionality, then an IETF order to implement some desired new functionality, then an IETF
"Standards Action" or "IESG Approval" specification [RFC5226] MUST "Standards Action" or "IESG Approval" specification [RFC5226] MUST
be published describing the new functionality. be published describing the new functionality.
This sentence implies that any designation of a special-use name is This sentence implies that any designation of a special-use name is
subject to the same open review and consensus process as used to subject to the same open review and consensus process as used to
produce and publish all other IETF specifications. produce and publish all other IETF specifications.
The registration process is a purely mechanical process, in which the The registration process is a purely mechanical process, in which the
existence of the newly designated special use name is recorded, with existence of the newly designated special use name is recorded, with
a pointer to a section in the relevant specification document that a pointer to a section in the relevant specification document that
defines the ways in which special handling is to be applied to the defines the ways in which special handling is to be applied to the
name. name.
RFC6761 provided the process whereby Multicast DNS [RFC6762] RFC6761 provided the process whereby Multicast DNS [RFC6762]
designated ".local" as a special-use name and included it in the designated ".local" as a SUDN and included it in the Special-Use
Special-Use Names registry. It itself also enumerated a set of names Domain Names registry. It itself also enumerated a set of names that
that had been previously used or defined to have special uses prior had been previously used or defined to have special uses prior to the
to the publication of RFC6761. Since there had been no registry for publication of RFC6761. Since there had been no registry for these
these names prior to the publication of RFC 6761, the documents names prior to the publication of RFC 6761, the documents defining
defining these names could not have added them to the registry. these names could not have added them to the registry.
There are at least several important points to think of with respect There are at least several important points to think of with respect
to the RFC6761: to the RFC6761:
o A special-use name may be a name that should be resolved using the o A special-use name may be a name that should be resolved using the
DNS protocol with no special handling. An example of this is 'IN- DNS protocol with no special handling. An example of this is 'IN-
ADDR.ARPA.' ADDR.ARPA.'
o A special-use name may be a name that is resolved using the DNS o A special-use name may be a name that is resolved using the DNS
protocol, requires no special handling in the stub resolver, but protocol, requires no special handling in the stub resolver, but
skipping to change at page 9, line 48 skipping to change at page 10, line 27
local stub resolver should use a non-DNS protocol for name local stub resolver should use a non-DNS protocol for name
resolution. resolution.
o The current IETF consensus (from a process perspective, not o The current IETF consensus (from a process perspective, not
necessarily from the perspective of what would be consensus if the necessarily from the perspective of what would be consensus if the
IETF were to attempt to produce a new consensus document) is that IETF were to attempt to produce a new consensus document) is that
all of these purposes for special-use names are valid. all of these purposes for special-use names are valid.
The term "stub resolver" in this case does not mean "DNS protocol The term "stub resolver" in this case does not mean "DNS protocol
stub resolver." The stub resolver is the entity within a particular stub resolver." The stub resolver is the entity within a particular
software stack that takes a question about a Domain name and answers software stack that takes a question about a Domain Name and answers
it. One way a stub resolver can answer such a question is using the it. One way a stub resolver can answer such a question is using the
DNS protocol, but it is in the stub resolver, as we are using the DNS protocol, but it is in the stub resolver, as we are using the
term here, that the decision as to whether to use a protocol, and if term here, that the decision as to whether to use a protocol, and if
so which protocol, or whether to use a local database of some sort, so which protocol, or whether to use a local database of some sort,
is made. is made.
RFC6761 does not limit special-use names to TLDs. However, at RFC6761 does not limit special-use names to TLDs. However, at
present, all special-use names registered in the IANA Special-Use present, all special-use names registered in the IANA Special-Use
Domain Names registry [SDO-IANA-SUDR] are either intended to be Domain Names registry [SDO-IANA-SUDR] are either intended to be
resolved using the DNS protocol, or are top-level domains, or both. resolved using the DNS protocol, or are top-level domains, or both.
That is, at present there exist no special-use names which require That is, at present there exist no special-use names which require
special handling by stub resolvers and which are not at the top level special handling by stub resolvers and which are not at the top level
of the naming hierarchy. of the naming hierarchy.
One point to take from this is that there is already a requirement in One point to take from this is that there is already a requirement in
RFC6762 that when stub resolvers encounter the special label, RFC6762 that when stub resolvers encounter the special label,
'.LOCAL' at the top level of a domain name, they can only use the '.LOCAL' at the top level of a domain name, they can only use the
mDNS protocol be used for resolving that domain name. mDNS protocol be used for resolving that Domain Name.
4.1.3. MoU Concerning the Technical Work of the IANA 4.1.3. MoU Concerning the Technical Work of the IANA
There exists a Memorandum of Understanding[RFC2860] between the IETF There exists a Memorandum of Understanding[RFC2860] between the IETF
and ICANN (Internet Corporation for Assigned Names and Numbers) which and ICANN (Internet Corporation for Assigned Names and Numbers) which
discusses how names and numbers will be managed through the IANA discusses how names and numbers will be managed through the IANA
(Internet Assigned Numbers Authority). This document is important to (Internet Assigned Numbers Authority). This document is important to
the discussion of SUDNs because, while it delegates authority for the discussion of SUDNs because, while it delegates authority for
managing the Domain Name System Namespace generally to ICANN, it managing the Domain Name System Namespace generally to ICANN, it
reserves to the IETF the authority that RFC 6761 formalizes: reserves to the IETF the authority that RFC 6761 formalizes:
Note that (a) assignments of domain names for technical uses (such Note that (a) assignments of Domain Names for technical uses (such
as domain names for inverse DNS lookup), (b) assignments of as Domain Names for inverse DNS lookup), (b) assignments of
specialised address blocks (such as multicast or anycast blocks), specialised address blocks (such as multicast or anycast blocks),
and (c) experimental assignments are not considered to be policy and (c) experimental assignments are not considered to be policy
issues, and shall remain subject to the provisions of this issues, and shall remain subject to the provisions of this
Section 4. Section 4.
The above text is an addendum to the following: The above text is an addendum to the following:
Two particular assigned spaces present policy issues in addition Two particular assigned spaces present policy issues in addition
to the technical considerations specified by the IETF: the to the technical considerations specified by the IETF: the
assignment of domain names, and the assignment of IP address assignment of Domain Names, and the assignment of IP address
blocks. These policy issues are outside the scope of this MOU. blocks. These policy issues are outside the scope of this MOU.
In general, then, the assignment of names in the DNS root zone, and In general, then, the assignment of names in the DNS root zone, and
the management of the DNS namespace, is a function that is performed the management of the DNS namespace, is a function that is performed
by ICANN. However, the MoU specifically exempts domain names by ICANN. However, the MoU specifically exempts domain names
assigned for technical use, and uses the example of domains used for assigned for technical use, and uses the example of domains used for
inverse DNS lookup. Both 'IN-ADDR.ARPA' and 'IP6.ARPA' are in the inverse DNS lookup. Both 'IN-ADDR.ARPA' and 'IP6.ARPA' are in the
special-use domain names registry. special-use Domain Names registry.
The point here is not to say what the implications of this statement The point here is not to say what the implications of this statement
in the MoU are, but rather to call the reader's attention to the in the MoU are, but rather to call the reader's attention to the
existence of this statement. existence of this statement.
4.2. Secondary documents relating to the SUTLDN question 4.2. Secondary documents relating to the SUTLDN question
In addition to these documents, there are several others with which In addition to these documents, there are several others with which
participants in this discussion should be familiar. participants in this discussion should be familiar.
skipping to change at page 12, line 21 skipping to change at page 12, line 47
Locally Served DNS Zones [RFC6303] describes a particular use case Locally Served DNS Zones [RFC6303] describes a particular use case
for zones that exist by definition, and that are resolved using the for zones that exist by definition, and that are resolved using the
DNS protocol, but that cannot have a global meaning, because the host DNS protocol, but that cannot have a global meaning, because the host
IP addresses they reference are not unique. This applies to a IP addresses they reference are not unique. This applies to a
variety of addresses, including Private IPv4 addresses [RFC1918], variety of addresses, including Private IPv4 addresses [RFC1918],
Unique Local IPv6 Unicast Addresses [RFC4193] (in which this practice Unique Local IPv6 Unicast Addresses [RFC4193] (in which this practice
was first described) and IANA-Reserved IPv4 Prefix for Shared Address was first described) and IANA-Reserved IPv4 Prefix for Shared Address
Space [RFC6598]. Space [RFC6598].
This use case is distinct from the use-case for SUTLDNs like '.local' This use case is distinct from the use-case for SUTLDNs like '.local'
and '.onion' in that the names are resolved using the DNS protocol. and '.onion' in that the names are resolved using the DNS protocol
But it shares the problem that such names cannot be assumed either to (but do require extensions or exceptions to the usual DNS resolution
be unique or to be functional in all contexts for all Internet- to enforce resolution in a local context rather than the global DNS
connected hosts. context). But it shares the problem that such names cannot be
assumed either to be unique or to be functional in all contexts for
all Internet-connected hosts.
4.2.4. Name Collision in the DNS 4.2.4. Name Collision in the DNS
Name Collision in the DNS [SDO-ICANN-COLL] is a study commissioned by Name Collision in the DNS [SDO-ICANN-COLL] is a study commissioned by
ICANN that attempts to characterize the potential risk to the ICANN that attempts to characterize the potential risk to the
Internet of adding global DNS delegations for names that were not Internet of adding global DNS delegations for names that were not
previously delegated in the DNS, not reserved under any RFC, but also previously delegated in the DNS, not reserved under any RFC, but also
known to be (.home) or surmised to be (.corp) in significant use for known to be (.home) or surmised to be (.corp) in significant use for
special-use-type reasons (local scope DNS, or other resolution special-use-type reasons (local scope DNS, or other resolution
protocols altogether). protocols altogether).
4.2.5. Discovery of the IPv6 Prefix Used for IPv6 Address Synthesis 4.2.5. SSAC Advisory on the Stability of the Domain Namespace
This document reports on some issues surrounding the conflicting
uses, interested parties and processes related to the Domain
Namespace. The document recommends the development of collaborative
processes among the various interested parties to coordinate their
activities related to the Domain Namespace.
4.2.6. Discovery of the IPv6 Prefix Used for IPv6 Address Synthesis
Discovery of the IPv6 Prefix Used for IPv6 Address Synthesis Discovery of the IPv6 Prefix Used for IPv6 Address Synthesis
[RFC7050] is an example of a document that successfully used the RFC [RFC7050] is an example of a document that successfully used the RFC
6761 process to designate '.ipv4only.arpa' as a special-use name; in 6761 process to designate '.ipv4only.arpa' as a special-use name; in
this case the process worked smoothly and without controversy. this case the process worked smoothly and without controversy.
Unfortunately, while the IETF process worked smoothly, in the sense Unfortunately, while the IETF process worked smoothly, in the sense
that there was little controversy or delay in approving the new use, that there was little controversy or delay in approving the new use,
it did not work correctly: the name 'ipv4only.arpa' was never added it did not work correctly: the name 'ipv4only.arpa' was never added
to the special-use domain names registry. This appears to have to the special-use Domain Names registry. This appears to have
happened because the IAB was able to simply add the name to the .ARPA happened because the IAB was able to simply add the name to the .ARPA
zone, which the IAB administers. This is an illustration of one of zone, which the IAB administers. This is an illustration of one of
the problems that we have with the 6761 process: it is apparently the problems that we have with the 6761 process: it is apparently
fairly easy to miss the step of adding the name to the registry. fairly easy to miss the step of adding the name to the registry.
4.2.6. Additional Reserved Top Level Domains 4.2.7. Additional Reserved Top Level Domains
Additional Reserved Top Level Domains Additional Reserved Top Level Domains
[I-D.chapin-additional-reserved-tlds] is an example of a document [I-D.chapin-additional-reserved-tlds] is an example of a document
that attempted to reserve several TLDs identified by ICANN as that attempted to reserve several TLDs identified by ICANN as
particularly at risk for collision as special-use domain names with particularly at risk for collision as special-use Domain Names with
no documented use. This attempt failed. no documented use. This attempt failed.
Although this document failed to gain consensus to publish, the need Although this document failed to gain consensus to publish, the need
it was intended to fill still exists. Unfortunately, although a fair it was intended to fill still exists. Unfortunately, although a fair
amount is known about the use of these names, no document exists that amount is known about the use of these names, no document exists that
documents how they are used, and why it would be a problem to documents how they are used, and why it would be a problem to
delegate them. Additionally, to the extent that the uses being made delegate them. Additionally, to the extent that the uses being made
of these names are valid, no document exists indicating when it might of these names are valid, no document exists indicating when it might
make sense to use them, and when it would not make sense to use them. make sense to use them, and when it would not make sense to use them.
RFC 7788 [RFC7788] defines the Domain Name TLD ".home" for use as the
default name for name resolution relative to a home network context.
Although, as define in RFC 7788, ".home" is a special-use Domain
Name, RFC 7788 did not follow the process in RFC 6761 and request the
addition of ".home" to the IANA Special-Use Domain Name registry.
Additionally, ".home" is an example of an attempt to reuse a Domain
Name that has already been commandeered for other purposes
[SDO-ICANN-COLL], which further complicates the situation. At the
time this document was written, the IETF was developing a solution to
this problem.
4.3. Summary 4.3. Summary
How names are resolved is ambiguous, in the sense that some names are How names are resolved is ambiguous, in the sense that some names are
special-use names that require special handling, and some names can special-use names that require special handling, and some names can
be resolved using the DNS protocol with no special handling. be resolved using the DNS protocol with no special handling.
The assignment of Internet Names is not under the sole control of any The assignment of Internet Names is not under the sole control of any
one organization. IETF has authority in some cases, but only with one organization. IETF has authority in some cases, but only with
respect to "technical uses." ICANN at present is the designated respect to "technical uses." ICANN at present is the designated
administrator of the root zone, but generally not of zones other than administrator of the root zone, but generally not of zones other than
the root zone. And neither of these authorities can in any practical the root zone. And neither of these authorities can in any practical
sense exclude the practice of ad-hoc use of names. This can be done sense exclude the practice of ad-hoc use of names. This can be done
by any entity that has control over one or more name servers or by any entity that has control over one or more name servers or
resolvers, in the context of any hosts and services that that entity resolvers, in the context of any hosts and services that that entity
operates. It can also be done by authors of software who decide that operates. It can also be done by authors of software who decide that
a special-use name is the right way to indicate the use of an a special-use name is the right way to indicate the use of an
alternate resolution mechanism. alternate resolution mechanism.
5. History 5. History
Newcomers to the problem of resolving domain names may be under the Newcomers to the problem of resolving Domain Names may be under the
mistaken impression that the DNS sprang, as in the Greek legend of mistaken impression that the DNS sprang, as in the Greek legend of
Athena, directly from Paul Mockapetris' forehead. This is not the Athena, directly from Paul Mockapetris' forehead. This is not the
case. At the time of the writing of the IAB technical document, case. At the time of the writing of the IAB technical document,
memories would have been fresh of the evolutionary process that led memories would have been fresh of the evolutionary process that led
to the DNS' dominance as a protocol for domain name resolution. to the DNS' dominance as a protocol for Domain Name resolution.
In fact, in the early days of the Internet, hostnames were resolved In fact, in the early days of the Internet, hostnames were resolved
using a text file, HOSTS.TXT, which was maintained by a central using a text file, HOSTS.TXT, which was maintained by a central
authority, the Network Information Center, and distributed to all authority, the Network Information Center, and distributed to all
hosts on the Internet using the File Transfer Protocol (FTP) hosts on the Internet using the File Transfer Protocol (FTP)
[RFC0959]. The inefficiency of this process is cited as a reason for [RFC0959]. The inefficiency of this process is cited as a reason for
the development of the DNS [RFC0882] [RFC0883] in 1983. the development of the DNS [RFC0882] [RFC0883] in 1983.
However, the transition from HOSTS.TXT to the DNS was not smooth. However, the transition from HOSTS.TXT to the DNS was not smooth.
For example, Sun Microsystems's Network Information System For example, Sun Microsystems's Network Information System
[CORP-SUN-NIS], at the time known as Yellow Pages, was an active [CORP-SUN-NIS], at the time known as Yellow Pages, was an active
competitor to the DNS, although it failed to provide a complete competitor to the DNS, although it failed to provide a complete
solution to the global naming problem. solution to the global naming problem.
Another example was NetBIOS Name Service, also known as WINS Another example was NetBIOS Name Service, also known as WINS
skipping to change at page 14, line 26 skipping to change at page 15, line 23
machines, but also by open source BSD and Linux operating systems to machines, but also by open source BSD and Linux operating systems to
do name resolution using Microsoft's own name resolution protocol. do name resolution using Microsoft's own name resolution protocol.
Most modern operating systems can still use the '/etc/hosts' file for Most modern operating systems can still use the '/etc/hosts' file for
name resolution. Many still have a name service switch that can be name resolution. Many still have a name service switch that can be
configured on the host to resolve some domains using NIS or WINS. configured on the host to resolve some domains using NIS or WINS.
Most have the capability to resolve names using mDNS by recognizing Most have the capability to resolve names using mDNS by recognizing
the special meaning of the '.local' SUTLDN. the special meaning of the '.local' SUTLDN.
The Sun Microsystems model of having private domains within a The Sun Microsystems model of having private domains within a
corporate site, while supporting the global domain name system for corporate site, while supporting the global Domain Name system for
off-site, persisted even after the NIS protocol fell into disuse. off-site, persisted even after the NIS protocol fell into disuse.
Microsoft used to recommend that site administrators use a "private" Microsoft used to recommend that site administrators use a "private"
top-level domain for internal use, and this practice was very much a top-level domain for internal use, and this practice was very much a
part of the zeitgeist at the time (see section 5.1 of part of the zeitgeist at the time (see section 5.1 of
[SDO-ICANN-COLL] and Appendix G of [RFC6762]). This attitude is at [SDO-ICANN-COLL] and Appendix G of [RFC6762]). This attitude is at
the root of the widespread practice of simply picking an unused top- the root of the widespread practice of simply picking an unused top-
level domain and using it for experimental purposes, which persists level domain and using it for experimental purposes, which persists
even at the time of writing of this memo. even at the time of writing of this memo.
This history is being presented because discussions about special-use This history is being presented because discussions about special-use
names in the IETF often come down to the question of why users of new names in the IETF often come down to the question of why users of new
name resolution protocols choose to use Domain names, rather than name resolution protocols choose to use Domain Names, rather than
using some other naming concept that doesn't overlap with the using some other naming concept that doesn't overlap with the
namespace that, in modern times is, by default, resolved using the namespace that, in modern times is, by default, resolved using the
DNS. DNS.
The answer is that as a consequence of this long history of resolving The answer is that as a consequence of this long history of resolving
Domain Names using a wide variety of name resolution systems, Domain Domain Names using a wide variety of name resolution systems, Domain
Names are required in a large variety of contexts in user interfaces Names are required in a large variety of contexts in user interfaces
and applications programming interfaces. Any name that appears in and applications programming interfaces. Any name that appears in
such a context is a Domain Name. So developers of new name such a context is a Domain Name. So developers of new name
resolution systems that must work in existing contexts actually have resolution systems that must work in existing contexts actually have
skipping to change at page 15, line 26 skipping to change at page 16, line 26
Ralph started out as an innocent bystander, but discussion with him Ralph started out as an innocent bystander, but discussion with him
was the key motivating factor in the writing of this document, and he was the key motivating factor in the writing of this document, and he
agreed to co-author it without too much arm-twisting. Warren spent a agreed to co-author it without too much arm-twisting. Warren spent a
lot of time working with us on this document after it was first lot of time working with us on this document after it was first
published, and joined as an author in order to make sure that the published, and joined as an author in order to make sure that the
work got finished; without him the -01 and -02 versions might not work got finished; without him the -01 and -02 versions might not
have happened. have happened.
This document also owes a great deal to Ed Lewis' excellent work on This document also owes a great deal to Ed Lewis' excellent work on
what a "domain name" is [I-D.lewis-domain-names]. what a "Domain Name" is [I-D.lewis-domain-names].
7. Informative References 7. Informative References
[RFC0882] Mockapetris, P., "Domain names: Concepts and facilities", [RFC0882] Mockapetris, P., "Domain names: Concepts and facilities",
RFC 882, DOI 10.17487/RFC0882, November 1983, RFC 882, DOI 10.17487/RFC0882, November 1983,
<http://www.rfc-editor.org/info/rfc882>. <http://www.rfc-editor.org/info/rfc882>.
[RFC0883] Mockapetris, P., "Domain names: Implementation [RFC0883] Mockapetris, P., "Domain names: Implementation
specification", RFC 883, DOI 10.17487/RFC0883, November specification", RFC 883, DOI 10.17487/RFC0883, November
1983, <http://www.rfc-editor.org/info/rfc883>. 1983, <http://www.rfc-editor.org/info/rfc883>.
[RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", [RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", STD
STD 9, RFC 959, DOI 10.17487/RFC0959, October 1985, 9, RFC 959, DOI 10.17487/RFC0959, October 1985,
<http://www.rfc-editor.org/info/rfc959>. <http://www.rfc-editor.org/info/rfc959>.
[RFC1002] NetBIOS Working Group in the Defense Advanced Research [RFC1002] NetBIOS Working Group in the Defense Advanced Research
Projects Agency, Internet Activities Board, and End-to-End Projects Agency, Internet Activities Board, and End-to-End
Services Task Force, "Protocol standard for a NetBIOS Services Task Force, "Protocol standard for a NetBIOS
service on a TCP/UDP transport: Detailed specifications", service on a TCP/UDP transport: Detailed specifications",
STD 19, RFC 1002, DOI 10.17487/RFC1002, March 1987, STD 19, RFC 1002, DOI 10.17487/RFC1002, March 1987,
<http://www.rfc-editor.org/info/rfc1002>. <http://www.rfc-editor.org/info/rfc1002>.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
skipping to change at page 16, line 20 skipping to change at page 17, line 20
and E. Lear, "Address Allocation for Private Internets", and E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
<http://www.rfc-editor.org/info/rfc1918>. <http://www.rfc-editor.org/info/rfc1918>.
[RFC2826] Internet Architecture Board, "IAB Technical Comment on the [RFC2826] Internet Architecture Board, "IAB Technical Comment on the
Unique DNS Root", RFC 2826, DOI 10.17487/RFC2826, May Unique DNS Root", RFC 2826, DOI 10.17487/RFC2826, May
2000, <http://www.rfc-editor.org/info/rfc2826>. 2000, <http://www.rfc-editor.org/info/rfc2826>.
[RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of [RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
Understanding Concerning the Technical Work of the Understanding Concerning the Technical Work of the
Internet Assigned Numbers Authority", RFC 2860, Internet Assigned Numbers Authority", RFC 2860, DOI
DOI 10.17487/RFC2860, June 2000, 10.17487/RFC2860, June 2000,
<http://www.rfc-editor.org/info/rfc2860>. <http://www.rfc-editor.org/info/rfc2860>.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005, Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
<http://www.rfc-editor.org/info/rfc4193>. <http://www.rfc-editor.org/info/rfc4193>.
[RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163, [RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163, RFC
RFC 6303, DOI 10.17487/RFC6303, July 2011, 6303, DOI 10.17487/RFC6303, July 2011,
<http://www.rfc-editor.org/info/rfc6303>. <http://www.rfc-editor.org/info/rfc6303>.
[RFC6598] Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and [RFC6598] Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and
M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address
Space", BCP 153, RFC 6598, DOI 10.17487/RFC6598, April Space", BCP 153, RFC 6598, DOI 10.17487/RFC6598, April
2012, <http://www.rfc-editor.org/info/rfc6598>. 2012, <http://www.rfc-editor.org/info/rfc6598>.
[RFC6760] Cheshire, S. and M. Krochmal, "Requirements for a Protocol [RFC6760] Cheshire, S. and M. Krochmal, "Requirements for a Protocol
to Replace the AppleTalk Name Binding Protocol (NBP)", to Replace the AppleTalk Name Binding Protocol (NBP)", RFC
RFC 6760, DOI 10.17487/RFC6760, February 2013, 6760, DOI 10.17487/RFC6760, February 2013,
<http://www.rfc-editor.org/info/rfc6760>. <http://www.rfc-editor.org/info/rfc6760>.
[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names", [RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, DOI 10.17487/RFC6761, February 2013, RFC 6761, DOI 10.17487/RFC6761, February 2013,
<http://www.rfc-editor.org/info/rfc6761>. <http://www.rfc-editor.org/info/rfc6761>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013, DOI 10.17487/RFC6762, February 2013,
<http://www.rfc-editor.org/info/rfc6762>. <http://www.rfc-editor.org/info/rfc6762>.
[RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of [RFC7050] Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
the IPv6 Prefix Used for IPv6 Address Synthesis", the IPv6 Prefix Used for IPv6 Address Synthesis", RFC
RFC 7050, DOI 10.17487/RFC7050, November 2013, 7050, DOI 10.17487/RFC7050, November 2013,
<http://www.rfc-editor.org/info/rfc7050>. <http://www.rfc-editor.org/info/rfc7050>.
[RFC7686] Appelbaum, J. and A. Muffett, "The ".onion" Special-Use [RFC7686] Appelbaum, J. and A. Muffett, "The ".onion" Special-Use
Domain Name", RFC 7686, DOI 10.17487/RFC7686, October Domain Name", RFC 7686, DOI 10.17487/RFC7686, October
2015, <http://www.rfc-editor.org/info/rfc7686>. 2015, <http://www.rfc-editor.org/info/rfc7686>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <http://www.rfc-editor.org/info/rfc7788>.
[I-D.chapin-additional-reserved-tlds] [I-D.chapin-additional-reserved-tlds]
Chapin, L. and M. McFadden, "Additional Reserved Top Level Chapin, L. and M. McFadden, "Additional Reserved Top Level
Domains", draft-chapin-additional-reserved-tlds-02 (work Domains", draft-chapin-additional-reserved-tlds-02 (work
in progress), March 2015. in progress), March 2015.
[I-D.lewis-domain-names] [I-D.lewis-domain-names]
Lewis, E., "Domain Names", draft-lewis-domain-names-04 Lewis, E., "Domain Names", draft-lewis-domain-names-04
(work in progress), September 2016. (work in progress), September 2016.
[SDO-CABF-INT] [SDO-CABF-INT]
CA/Browser Forum, "Guidance on the Deprecation of Internal CA/Browser Forum, "Guidance on the Deprecation of Internal
Server Names and Reserved IP Addresses", June 2012, Server Names and Reserved IP Addresses", June 2012,
<https://www.digicert.com/internal-names.htm>. <https://www.digicert.com/internal-names.htm>.
[SDO-ICANN-COLL] [SDO-ICANN-COLL]
Interisle Consulting Group, LLC, "Name Collisions in the Interisle Consulting Group, LLC, "Name Collisions in the
DNS", August 2013, DNS", August 2013,
<https://www.icann.org/en/system/files/files/name- <https://www.icann.org/en/system/files/files/name-
collision-02aug13-en.pdf>. collision-02aug13-en.pdf>.
[SDO-ICANN-SAC090]
ICANN Security and Stability Advisory Committee, "SSAC
Advisory on the Stability of the Domain Namespace",
December 2016,
<https://www.icann.org/en/system/files/files/sac-
090-en.pdf>.
[SDO-IANA-SUDR] [SDO-IANA-SUDR]
Internet Assigned Numbers Authority, "Special-Use Domain Internet Assigned Numbers Authority, "Special-Use Domain
Names registry", October 2015, Names registry", October 2015,
<http://www.iana.org/assignments/special-use-domain-names/ <http://www.iana.org/assignments/special-use-domain-names/
special-use-domain-names.xhtml>. special-use-domain-names.xhtml>.
[SDO-ICANN-DAG]
Internet Assigned Numbers Authority, "Special-Use Domain
Names registry", October 2015,
<https://newgtlds.icann.org/en/applicants/agb/guidebook-
full-04jun12-en.pdf>.
[CORP-SUN-NIS] [CORP-SUN-NIS]
Sun Microsystems, "Large System and Network Sun Microsystems, "Large System and Network
Administration", March 1990. Administration", March 1990.
[IETF-PRO-51] [IETF-PRO-51]
Internet Engineering Task Force, "Proceedings of the 51st Internet Engineering Task Force, "Proceedings of the 51st
IETF", August 2001, IETF", August 2001,
<http://www.ietf.org/proceedings/51/51-45.htm#TopOfPage>. <http://www.ietf.org/proceedings/51/51-45.htm#TopOfPage>.
Appendix A. Change Log. Appendix A. Change Log.
-00 to -01:
Improved the terminology.
Included reference to SAC090.
Added ICANN Reserved Names (e.g .icann, .iesg, .arin) to types of
names.
Improved background.
Noted that semantics may differ between resolution contexts.
Pointer to .home / .corp / .mail, other "toxic" names
Readability fixes.
-04 to ietf-00
Document adopted by WG.
Significant changes from CfA integrated, please refer to diff.
-03 to -04: -03 to -04:
o Replaced 'Internet Names' with 'Domain Names' - suggestion by John o Replaced 'Internet Names' with 'Domain Names' - suggestion by John
Levine. Levine.
-02 to -03: -02 to -03:
o Readability fixes, small grammar updates. o Readability fixes, small grammar updates.
-01 to -02: -01 to -02:
o Cleaned up the abstract. o Cleaned up the abstract.
o Fixed the case of Internet o Fixed the case of Internet
o Reference to Ed Lewis' "domain names" o Reference to Ed Lewis' "Domain Names"
o Fleshed out the problems, primarily the coordination, collisions o Fleshed out the problems, primarily the coordination, collisions
ones. ones.
-00 to -01: -00 to -01:
o Large refactoring, basically a rewrite. Incorporated comments, o Large refactoring, basically a rewrite. Incorporated comments,
removed a bunch of unneeded text, etc. removed a bunch of unneeded text, etc.
Authors' Addresses Authors' Addresses
 End of changes. 57 change blocks. 
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