Network Working Group                                           J. Abley
Internet-Draft                                                 Dyn, Inc.
Intended status: Informational                                   P. Koch
Expires: September 21, 2016                                     DENIC eG
                                                               A. Durand
                                                               W. Kumari
                                                          March 20, 2016

   Problem Statement for the Reservation of Top-Level Domains in the
                   Special-Use Domain Names Registry


   The dominant protocol for name resolution on the Internet is the
   Domain Name System (DNS).  However, other protocols exist that are
   fundamentally different from the DNS, and may or may not share the
   same namespace.

   When an end-user triggers resolution of a name on a system which
   supports multiple, different protocols (or resolution mechanisms) for
   name resolution, it is desirable that the protocol used is
   unambiguous, and that requests intended for one protocol are not
   inadvertently answered using another.

   RFC 6761 introduced a framework by which, under certain
   circumstances, a particular domain name could be acknowledged as
   being special.  This framework has been used twice to reserve top-
   level domains (.local and .onion) that should not be used within the
   DNS, to avoid the possibility of namespace collisions in parallel use
   of non-DNS name resolution protocols.

   Various challenges have become apparent with this application of the
   guidance provided in RFC 6761.  This document aims to document those
   challenges in the form of a problem statement, to facilitate further
   discussion of potential solutions.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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

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   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   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."

   This Internet-Draft will expire on September 21, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  RFC 6761  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Architectural Considerations  . . . . . . . . . . . . . . . .   6
   5.  Technical Considerations  . . . . . . . . . . . . . . . . . .   8
   6.  Organizational Considerations . . . . . . . . . . . . . . . .   9
     6.1.  External Organizational Considerations  . . . . . . . . .   9
     6.2.  IETF Internal Considerations  . . . . . . . . . . . . . .  10
       6.2.1.  Process . . . . . . . . . . . . . . . . . . . . . . .  10
       6.2.2.  Technical Criteria  . . . . . . . . . . . . . . . . .  11
       6.2.3.  Name evaluation . . . . . . . . . . . . . . . . . . .  12
     6.3.  The ICANN process to evaluate names . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     10.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Appendix A.  Editorial Notes  . . . . . . . . . . . . . . . . . .  16
     A.1.  Venue . . . . . . . . . . . . . . . . . . . . . . . . . .  17
     A.2.  Pithy Quotes from History . . . . . . . . . . . . . . . .  17

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     A.3.  Change History  . . . . . . . . . . . . . . . . . . . . .  17
       A.3.1.  draft-adpkja-special-names-problem-00 . . . . . . . .  17
   Appendix B.  Change history . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Terminology

   Clear and unambiguous use of terminology is important for the clear
   formulation of any problem statement.  The DNS protocol suffers from
   imprecise and overloaded terminology (for example, see [RFC7719]).
   The use of terms and concepts from other naming systems that are
   similar (but different) simply confuses matters further.

   In the interests of clarity, the following terms used in this
   document are to be interpreted as follows:

      Registry (n): the Special-Use Domain Names Registry created by
      [RFC6761] and published at [IANA-SPECIAL-USE].

   [This section to be completed following review and refinement of the
   rest of the text.]

2.  Introduction

   Some systems use the last label in a name to act as a switch to a
   different, non-DNS resolution process - examples of such switches
   include: .local (to use mDNS) and .onion (to use Tor).  This switch
   practice is not explicitly documented anywhere, and the method for
   accomplishing this varies by implementation.  As an interesting
   aside, the full semantics of domain names isn't really documented
   anywhere either, although [I-D.lewis-domain-names] is a current
   attempt to rectify this.

   This technique of using the last label as a switch has a number of
   properties which make it attractive to people implementing alternate
   name resolution systems, including:

   o  The names can follow the common DNS syntax of LDH labels,
      separated by dots.  This means that these names can be entered in
      any application which takes existing DNS names.

   o  The switch to the new resolution process can be implemented in a
      number of ways, such as custom application code, a shim in the
      normal DNS resolution process, or on the system's configured DNS

   o  The names "look" like names to users.

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   Note that [RFC6303] defines "locally served zones".  The important
   difference is that in [RFC6303], the names get registered for special
   treatment if they are already special: they are not declared special
   by the registration.

   [RFC6761] defines ways to reserve domain names.  This could be read
   to augment the technical uses exemption made in [RFC2860] (also
   called "the IETF-ICANN MoU").  [RFC2860] says:

      "Note that (a) assignments of domain names for technical uses
      (such as domain names for inverse DNS lookup), (b) assignments of
      specialized address blocks (such as multicast or anycast blocks),
      and (c) experimental assignments are not considered to be policy
      issues, and shall remain subject to the provisions of this
      Section 4."

   The framework in [RFC6761] has recently been used to reserve the
   .onion label, allowing it to be used as a switch to the Tor
   resolution process, as described in [RFC7686].  Because the .onion
   label in the IANA "Special-Use Domain Names" registry
   [IANA-SPECIAL-USE], the Tor Project can be assured that there will
   not be a .onion TLD created in the IANA rooted DNS, and thus the
   possibility of collisions in the namespace will be avoided.

   The discussions in the DNSOP Working Group (WG) and the IETF Last
   Call processes for the .onion registration in the Special Use Domain
   Names registry (1,200 messages) have made it apparent that clarity
   about if and how to treat this "protocol switching" practice would
   help a lot in deciding the merit of future similar applications.

   One possible outcome of the discussion would be to decline to
   recognize such usage of domain names in the architecture; another
   possible outcome is to formalize it and better understand the issues
   that come with it.

   An additional consideration is that names which follow the DNS syntax
   (including those which use alternate name resolutions processes to
   the DNS) are in the same namespace as names in the DNS.  This means
   that currently both the IETF (through [RFC6761]) and ICANN are making
   allocations or reservations from a shared namespace.  If this
   continues to be the case, in order to avoid conflict, close
   coordination between the two organizations is necessary.

3.  RFC 6761

   Section 5 of [RFC6761] describes seven questions to be answered to
   justify how and why a particular domain name is special.  These seven
   questions can be broadly categorized as follows:

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   1.  impact on end-users;

   2.  impact on applications;

   3.  impact on name resolution APIs and libraries;

   4.  impact on recursive resolvers;

   5.  impact on authoritative DNS servers;

   6.  impact on DNS server operators;

   7.  impact on DNS registries and registrars.

   The intent of those seven questions was originally to serve as the
   justifications for why a proposed special-use registration should be
   granted, demonstrating that it (a) provides a result that the
   community judges to be good, and (b) the aforementioned good result
   cannot reasonably be achieved in another way.  The rough consensus
   from significant discussion was that .onion did satisfy both (a) and
   (b), but this was not clearly demonstrated by the answers to the
   "seven questions".  Furthermore, it is unclear if and how these
   questions could reliably and unambiguously be used to make the
   determination, leading to the conclusion that they are generally
   inadequate for making the determination whether a particular domain
   name qualifies as requiring special/different treatment.
   Applications which follow the [RFC6761] process are likely to devolve
   into a "beauty contest".  Moreover, the answers to the seven
   questions are not available in a machine readable form to
   applications that want to follow [RFC6761].

   So the answers to these seven questions can better be seen as
   providing guidance to the corresponding seven audiences on how to
   handle a special-use domain name once it has been reserved by
   inclusion in the Registry, and not as entrance filters for inclusion
   in the registry.

   The answers to the seven questions specify desired behavior in the
   internet for handling a particular domain name, not the basis for
   deciding whether the effort to implement special behavior across all
   of those audiences is worth the cost.  This indifference to costs is
   not necessarily scalable for making future decisions about potential
   inclusion in the registry.

   The justification in [RFC6761] is concerned with the rationale of
   reserving a domain name that precludes its subsequent use as a top
   level domain name.  However, the document fails to offer such a
   rationale, and instead requires the justification of the reserved

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   name to include the provision of guidance to a number of audiences
   (users, application developers, DNS resolver applications, DNS
   resolution service operators, and name registries and registrars) as
   to how to handle names that are listed in this registry.  But this
   guidance is not, in and of itself, an adequate rationale for the
   selection of a particular name value to be reserved in this registry.

   What is missing in [RFC6761] is the consideration of the name itself.
   If one were to contrast the procedures relating to the admission of a
   name to the IETF Special Use Name registry to the processes
   associated with the New gTLD Program operated by ICANN [NEW-GTLD],
   then it is evident that the IETF process does not admit many
   considerations which appear to be areas of evaluation in the New gTLD
   program.  More on this in section Section 6.3.

   This document proposes to categorize considerations related to the
   usage of the [RFC6761] registry for protocol switches in 3
   categories: Architectural, Technical and Organizational.  This
   document then lists a number of questions to drive the discussion.
   The list of issues discussed here is non-exhaustive.

   However, some people have noted that [RFC6761] describes other
   alternative special handling aside from protocol switches.  That
   alternative special handling must be considered carefully at the time
   of publication of the defining RFC, regardless of the nature of the
   special use.

4.  Architectural Considerations

   The first thing to consider in this discussion is that not all names
   (or domain names) are part of the Domain Name System.  See
   [I-D.lewis-domain-names] for an in-depth discussion on this topic.

   At the time of writing, two top-level domain names reserved by
   inclusion in the Registry went through the [RFC6761] process and are
   used by name resolution protocols other than the DNS:

      .local is used by the Multicast DNS protocol specified in
      [RFC6762] which is similar in some respects to the DNS, but which
      uses a different well-known port number and is limited to a
      particular multicast scope;

      .onion is used to construct names that designate services
      reachable via the Tor network using onion routing.

   These two name resolution protocols are, to varying degrees,
   different from the DNS, and the namespaces used in each naming scheme
   are also different.  The top-level label is effectively being used as

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   a name resolution protocol identifier.  At the core of the issue is
   that different "strings" that look like "domain names" (i.e. are
   within the same name space) but are not DNS names are used
   interchangeably in the URI (or URN).

   In particular, DNS imposes constraints on name syntax.  An example of
   such constraints is the 63 octet limit per label.  Strings used in
   the .onion domain do not have that constraint.

   It could be argued that in the absence of a more elegant alternative,
   a pragmatic choice to embed protocol selectors as namespace tokens
   has effectively already been made.  The running code and effective
   consensus in how it should be used by significant user bases should
   not be discounted.  Although the reservation of names in the DNS
   namespace can be made at any level, the two examples above
   demonstrate use-cases for reservation at the top-level, and hence
   that case must be considered.

   The underlying discussion here is the tussle between the applications
   and the network.  Application architects see using special name tags
   (such as .onion) as an easy way to get new features deployed.  They
   consider the hurdles of deploying new URI schemes such as
   http:/onion/onion-name as too onerous and too slow to deploy for
   their needs.  Network architects worry of overloading the semantics
   of DNS names and/or creating a name space that is larger than the DNS
   namespace.  They refer to bad precedents such as .uucp and .bitnet.

   The fundamental point to consider here is the unicity (or
   multiplicity) of the name space.  Are we talking about one namespace
   with different resolution protocols or independent name spaces?

   It might it be helpful to point out that the property of interest
   here is the assurance of uniqueness of a name, and another way of
   thinking about the question is whether it applies across domain names
   as people expect or need it to?  None of this would matter if people
   didn't expect names constructed according to whatever rules they're
   following to be unique across a set of names that spans multiple
   operating environments and resolution protocols.

   In [RFC2826] the IAB noted that

      "To remain a global network, the Internet requires the existence
      of a globally unique public name space.  The DNS name space is a
      hierarchical name space derived from a single, globally unique

      "Maintaining a globally-unique public namespace that supports
      different name resolution protocols is hence an architectural

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      requirement, and some facility for reservation of top-level
      domains in the DNS is necessary."

   If we were to accept the notion that the last label of a domain name
   is actually a protocol switch, we are actually building a catalog of
   all top level domains and what resolution protocol each one invokes.
   Note that such a catalog does not formally exist today, because
   [RFC6761] is an exception list to the general case which is supposed
   to use regular DNS as resolution protocol.  Such a catalog may remain
   a concept to guide this discussion or be implemented as an actual
   IANA registry [IANA-SPECIAL-USE].  In effect, it would associate TLDs
   with indications on how applications and resolvers should treat them.
   However, such an approach would leave open the question of not-yet-
   defined TLDs.  No resolution mechanism could be associated with those
   in advance so that systems would have to continue to assume that such
   names are part of the DNS.  For reasons of completeness it is noted
   that suggestions have been made to help the distinction by using
   special labels (as in IDNs).

   It should also be noted that there are choices for a protocol switch
   other than reserving labels.  In particular, a proposal to move those
   protocol switches under a specific top level domain has been
   discussed (.ALT).  If that architecture choice is made, some of the
   questions listed in the sections below would become moot.

   Note: [RFC6761] mentions the reserved names could be any label in a
   domain name, not just the rightmost one (or ones).  However, this
   creates a number of complications and has not seen much support in
   the community as of now.

5.  Technical Considerations

   Each of the seven questions posed by [RFC6761] has the potential to
   describe why it may be necessary for special handling of the
   requested name(s) in applications by a particular audience.  However,
   aside from reserving the name, it is not entirely clear what any of
   those audiences might further expect as a result of a successful
   request to add a top-level domain to the Registry.

   For example, reservation of a top-level domain by the IETF does not
   guarantee that DNS queries for names within a reserved domain will
   not be sent over the Internet.  The requirements of the operators of
   recursive resolvers in the DNS cannot be relied upon to be
   implemented; the impact on the operators of DNS authoritative servers
   hence cannot be reliably assumed to be zero.  In the case of
   [RFC7686], leakage of .onion queries on the Internet might lead to
   disclosure of private information that, in some cases, might pose a
   risk to the personal safety of end-users.

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   At the time of writing, the [RFC6761] registry does not include
   direct guidance for any of the seven audiences, relying instead upon
   a reference for each entry in the Registry to the document that
   requested its insertion.  Such documents might well be opaque to many
   readers; [RFC6762] is a seventy-page protocol specification, for
   example, which is arguably not the most effective way to set
   expectations of non-technical end-users).

   Useful reservations of top-level domains should be accompanied by
   documentation of realistic expectations of each of the seven
   audiences, and the evaluation of particular requests should consider
   the practical likelihood of those expectations being met and the
   implications if they are not.

   Here is a non-exhaustive list of additional questions that have
   surfaced in discussion of requests for names to be added to the
   Special Use Names registry:

      What does it mean to have a "non-DNS" entry in the registry
      described above?

      Are applications supposed to check that registry to know what to

      Can, or should, applications do this check dynamically?

      What if an application makes this dynamic check and discovers the
      name contains a switch it does not know how to handle?

   Similar questions applies to resolvers (DNS and non-DNS); what is the
   expected behavior?

   One particular avenue of investigation would be to see if such
   considerations could be encoded in machine understandable code in an
   extension of the current [RFC6761] registry.

6.  Organizational Considerations

   This section gives two categories of organizational considerations:
   external and internal.

6.1.  External Organizational Considerations

   The policy surrounding the implementation and management of top-level
   domains in the DNS has been developed using a multi-stakeholder
   process convened by ICANN according to the MoU between ICANN and IETF
   [RFC2860].  It is out of scope for this document to revisit that MoU.

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   While discussing the particular attributes that make a domain name
   special, [RFC6761] notes that "the act of defining such a special
   name creates a higher-level protocol rule, above ICANN's management
   of allocatable names on the public Internet."

   [RFC2860] draws a line between what is policy and what is technical.
   A variety of opinions have been expressed regarding whether [RFC6761]
   blurs this line.  In particular, [HUSTON] has one viewpoint on the
   topic.  As noted earlier, it is out of scope for this document to
   analyse this issue beyond noting that such a variety of views exist.

   Taking a different perspective, it has been argued that [RFC6761]
   specifically extends the DNS protocol to include special treatment
   for names in the registry, and that there's nothing in [RFC2860] at
   all that limits the IETF's authority to change the protocol.

   However, it should be noted that, if the IETF were to formalize the
   concept of protocol/name switch in the Internet architecture,
   coordination would be require between ICANN and IETF on such names.
   Using the analogy described above of a catalog/registry of such
   switches, care must be taken to make sure we do not end up with two
   process streams allowed to create entries without complete

6.2.  IETF Internal Considerations

6.2.1.  Process

   [RFC6761] specifies the way in which "an IETF 'Standards Action' or
   'IESG Approval' document" should present answers to the questions
   described above (see Section 2), but does not describe the process by
   which the answers to those questions should be evaluated.

   For example, it is not clear who is responsible for carrying out an
   evaluation.  A document which requests additions to the Registry
   might be performed by the IESG, by the IAB, by the DNSOP WG, by an
   ad-hoc working group, by expert review or any combination of those
   approaches.  [RFC6761] provides no direction.

   As an illustration of the inconsistency that has been observed
   already, [RFC6762] was published as an AD-sponsored individual
   submission in the INT area, and the IESG evaluation record does not
   reveal any discussion of the reservation of the .local top-level
   domain in the DNS.  [RFC7686], however, was published as a working
   group document through the DNSOP WG, and an extensive discussion by
   both the participants of the DNSOP WG and the IESG on the merits of
   the request took place.  The evaluation process, in the absence of
   clear direction, is demonstrably inconsistent.

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   We should point to [RFC5226] and explicitly quote the definition of
   "Standards Action" or "IESG Approval":

      IESG Approval is not intended to be used often or as a "common
      case"; indeed, it has seldom been used in practice during the
      period RFC 2434 was in effect.  Rather, it is intended to be
      available in conjunction with other policies as a fall-back
      mechanism in the case where one of the other allowable approval
      mechanisms cannot be employed in a timely fashion or for some
      other compelling reason.  IESG Approval is not intended to
      circumvent the public review processes implied by other policies
      that could have been employed for a particular assignment.  IESG
      Approval would be appropriate, however, in cases where expediency
      is desired and there is strong consensus for making the assignment
      (e.g., WG consensus).

   So, while it is very interesting to note that [RFC6761] was an AD
   sponsored individual submission in spite of two active DNS related
   WGs, [RFC6762] is probably clean: it defines the protocol and is
   itself on standards track.

   [RFC7686] however, while on standards track, does not define the TOR
   protocol, so it was used to fulfill the 'standards action'
   requirement by the letter.  It contains normative references to non-
   IETF protocols, which is noteworthy.

   A comparison of the two "seven question forms" from [RFC6761] reveals
   that at least the responses to questions 2, 3, and 4, differ
   significantly while there is no defined way to communicate the
   difference to the affected software entities.

   An alternate view has been expressed with regard to the protocol
   evaluation.  It states that the authority belongs to the IESG to seek
   whatever support it likes, within the established process, in making
   standards decisions, including delegating evaluation of a specific
   registry change proposal to a WG or a directorate.  The IESG might
   have varied what guidance it sought, but that does not constitute
   "inconsistency" under the process.  That being said, more complete
   evaluation guidance would be helpful to the IESG and the community.

6.2.2.  Technical Criteria

   Regardless of the actual name being proposed as protocol and/or
   namespace switch, it is also not clear what technical criteria the
   evaluation body should use to examine the merit of an application for
   such a reserved name/protocol switch.  For example, is large scale
   prior deployment an acceptable criteria?  A number of people have

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   clearly answered "no" to that question as it would only encourage
   "squatting" on names.

   However, in the case of .local and .onion, those particular domain
   names were already in use by a substantial population of end-users at
   the time they were requested to be added to the Registry.  Rightly or
   not, the practical cost of a transition away from the requested
   strings was argued as a justification for their inclusion in the

6.2.3.  Name evaluation

   With regard to the actual choice of name, [RFC6761] is silent.  The
   answers to the seven questions are expected to tell how a name,
   presumably already chosen outside of the process, might be handled if
   it is determined to be a "special use" name.  However, it is silent
   on how to choose a name or how to evaluate a specific proposed name.

   Going back to the IETF process used for the evaluation of .local and
   .onion, one might ask the following questions:

      For example, what consideration have there been in the
      intellectual property rights in the reservation of a name in this
      Special Use Name registry, and what procedures should be followed
      in the case of a dispute over the rights to use a name in this
      manner?  Also, to what extent could such a reservation of a name
      in this Special Use Names registry be used to block competing
      interests and/or competing technologies?  What are the competition
      and consumer issues that need to be considered if the reservation
      of a name in this registry causes some form of exclusive access
      and reduced competitive access, or where there is no ability for
      consumers to exercise choice in a situation where providers
      compete in the offering of services?

      A related consideration is that the current process of admission
      to the Special Use Name registry appears to admit no formal
      assessment of environmental impact.  Is the name that is proposed
      to be entered into this registry already being used in local
      contexts, with or without an association with DNS name resolution,
      such that its use as a reserved name through an entry in this
      registry, and its continued use in local contexts could cause harm
      to users?  To what extent can this impact be assessed, and what
      level of impact is considered acceptable?

      While the "seven questions" relate to altered behaviors by
      specific audiences and users of names there is no explicit
      consideration of the security in this process.  Is the
      registration of such a name a "safe" action for the IETF to take?

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      To what extent could the use of this reserved name be used in a
      hostile or malicious manner?  What measures have been taken to
      mitigate or otherwise address such potential vulnerabilities?

   ICANN has created an entire set of groups, organizations, committees,
   processes and procedures to deal with the evaluation of applied for
   new TLDs, complete with a cadre of lawyers and policy people.  Unless
   the IETF were willing to do the same, it would have a hard time
   performing evaluation of the strings themselves, distinct from the
   evaluation of the technology behind the name resolution system.

   An alternate view has been expressed that such a process is not
   necessary because the IESG is the body that makes the decision on a
   specific name reserved by [RFC6761], and the IETF has a workable
   appeal process to deal with any potential issues.  However, looking
   at the level of contention created in the ICANN process around the
   choice of certain names, serious doubts have been expressed to the
   scalability and ultimate viability of such an appeal process.

6.3.  The ICANN process to evaluate names

   Section 4.3 of [RFC2860] says:

      Two particular assigned spaces present policy issues in addition
      to the technical considerations specified by the IETF: the
      assignment of domain names, and the assignment of IP address

   This remains as true today as when it was written (2000).  Domain
   names have a number of considerations that have complex policy issues
   that ICANN deals with and which the IETF may not be well equipped to

   The ICANN process applicant have to go through to get a name is
   described in the applicant guide book [GUIDEBOOK], which is a 338
   page document.  It should however be noted that the current round of
   gTLD application is closed and rules may differ in the next round if
   and when it happens.

   Considerations include, but are not limited to:

   Geographical  During the most recent round of new gTLD applications,
      there were a number of applications for so call "geographic"
      terms.  These included applications for .amazon and .patagonia.
      The .amazon application in particular was controversial - the
      governments of Brazil and Peru requested that ICANN's Governmental
      Advisory Committee (GAC) to issue a warning that granting .amazon
      to Amazon would "prevent the use of this domain for purposes of

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      public interest related to the protection, promotion, and
      awareness raising on issues related to the Amazon biome."  The
      IETF is not well suited to evaluating this sort of issue.

   Brands / Trademark law  If Wile E.  Coyote approached the IETF
      requesting that the IETF reserve .acme, a trademark held by a
      large corporation making anvils and giant slingshots, the IETF
      could become embroiled in trademark lawsuit - and even if the IETF
      were not, we have enough armchair lawyers that the discussions
      would be extremely annoying :-).  Closely related to this issue is
      "protected designation of origin (PDO)" - for example, Champagne.

   String similarity  ICANN has an entire process for evaluating the
      string similarity / confusability between applied for (and
      current) strings - for example, under what conditions would the
      IETF be able to make a determination if someone attempted to use
      [RFC6761] to reserve .c0m?

   International Organization Names  Certain names and organizations get
      additional protection under trademark law - well known examples of
      this are the RedCross/RedCrescent and the International Olympic
      Committee (IOC).  Whether or not this should be the case is well
      outside anything that the IETF should have an opinion on but,
      undoubtedly, there are many within the community who will have an
      opinion (and will want to argue it at length).

   Offensive Terms  There are a huge range of these, from the obscure /
      archaic (waesucks, gadsbudlikins) to the more obvious and current.
      Certain terms are sufficiently offensive that the IETF would have
      a hard time coming to any useful consensus (other then "Eeeew!")

7.  Security Considerations

   This document aims to provide a problem statement that will inform
   future work.  While security and privacy are fundamental
   considerations, this document expects that future work will include
   such analysis, and hence no attempt is made to do so here.  See among
   other places [SAC-057]

   Reserving names has been presented as a way to prevent leakage into
   the DNS.  However, instructing resolvers to not forward the queries
   (and/or by instructing authoritative servers not to respond) is not a
   guarantee that such leakage will be prevented.  The security (or
   privacy) of an application MUST NOT rely on names not being exposed
   to the Internet DNS resolution system.

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8.  IANA Considerations

   This document has no IANA actions.

9.  Acknowledgements

   Thanks to Paul Hoffman for a large amount of editing.

10.  References

10.1.  Normative References

              IANA, "Special-Use Domain Names", 2016,

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <>.

   [RFC2860]  Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
              Understanding Concerning the Technical Work of the
              Internet Assigned Numbers Authority", RFC 2860,
              DOI 10.17487/RFC2860, June 2000,

   [RFC6761]  Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
              RFC 6761, DOI 10.17487/RFC6761, February 2013,

   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              DOI 10.17487/RFC6762, February 2013,

   [RFC7686]  Appelbaum, J. and A. Muffett, "The ".onion" Special-Use
              Domain Name", RFC 7686, DOI 10.17487/RFC7686, October
              2015, <>.

10.2.  Informative References

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              ICANN, "gTLD Application Guidebook", June 2012,

   [HUSTON]   Huston, G., "What's in a Name?", December 2015,

              Lewis, E., "Domain Names", draft-lewis-domain-names-02
              (work in progress), January 2016.

              ICANN, "New Generic Top-Level Domains", 2016,

   [RFC1918]  Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
              and E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,

   [RFC2826]  Internet Architecture Board, "IAB Technical Comment on the
              Unique DNS Root", RFC 2826, DOI 10.17487/RFC2826, May
              2000, <>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,

   [RFC6303]  Andrews, M., "Locally Served DNS Zones", BCP 163,
              RFC 6303, DOI 10.17487/RFC6303, July 2011,

   [RFC7719]  Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", RFC 7719, DOI 10.17487/RFC7719, December
              2015, <>.

   [SAC-057]  ICANN Security and Stability Advisory Committee, "SSAC
              Advisory on Internal Name Certificates", March 2013,

Appendix A.  Editorial Notes

   This section (and sub-sections) to be removed prior to publication.

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A.1.  Venue

   An appropriate forum for discussion of this draft is for now the

A.2.  Pithy Quotes from History

      The question has arisen as to how the toplevel naming authority
      decides who gets a toplevel name and who must get by with a non-
      toplevel name.  The suggestion was made by MOCKAPETRIS@USC-ISIF
      that perhaps the existing toplevel nameholders might vote on
      whether the applicant for a new toplevel name should be granted,
      with a majority needed for approval.  It seems to me this might
      produce a clique whereby whoever initially gains power will hold
      it and prevent its "enemies" from getting in too.  This will make
      the toplevel rather less than universal.

   (E-mail from Robert Elton Maas to the namedroppers mailing list on 9
   November 1983)

      My basic point is that as a world-wide network evolves it is
      ridiculous to force people to name resources in terms of one
      static hierarchy which very closely resembles the current
      internetwork topology (as the current scheme does).  What we are
      eventually going to require is a distributed expert for making
      sense out of a name someone hands it.  There will be no simple
      algorithm to be written on one page of an RFC that will suffice to
      resolve a name.  Rather, a number of heuristics will let a
      resolver make sense out of a given name by querying other experts
      which it suspects may be more knowledgeable about the name than it
      is, or by forwarding a piece of mail to an expert which is at
      least one level closer to the destination in some hierarchy.

   (E-mail from Peter Karp to the namedroppers mailing list on 8
   February 1984)

A.3.  Change History

A.3.1.  draft-adpkja-special-names-problem-00

   Initial draft circulated for comment.

Appendix B.  Change history

   [ RFC Editor: Please remove this section before publication]

   -01 to -02:

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   o  A very large number of readability / grammar / reference fixes
      from Paul Hoffman.

   -00 to -01:

   o  Significant readability changes.


   o  Initial draft circulated for comment.

Authors' Addresses

   Joe Abley
   Dyn, Inc.
   103-186 Albert Street
   London, ON  N6A 1M1

   Phone: +1 519 670 9327

   Peter Koch
   Kaiserstrasse 75-77
   Frankfurt  60329


   Alain Durand


   Warren Kumari


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