Special-Use Domain Names
Problem Statement
Nominum, Inc.
800 Bridge Parkway
Redwood City
California
United States of America
94065
+1 650 381 6000
ted.lemon@nominum.com
rdroms.ietf@gmail.com
Google
1600 Amphitheatre Parkway
Mountain View, CA
94043
US
warren@kumari.net
The Special-Use Domain Names IANA registry policy defined in RFC 6761
has been shown through experience to present unanticipated challenges.
This memo presents a list, intended to be comprehensive, of the problems
that have been identified. In addition it reviews the history of Domain
Names and summarizes current IETF publications and some publications
from other organizations relating to Special-Use Domain Names.
One of the key services required to use the Internet is name
resolution. Name resolution is the process of translating a symbolic
name into some object or set of objects to which the name refers, most
typically one or more IP addresses. These names are often referred to as
Domain Names. When reading this document, care must be taken to not
assume that the term Domain Name implies the use of the Domain Name System for resolving these names. An
excellent presentation on this topic can be found in Domain Names.
Special-Use Domain Names created an IANA registry for Special-Use Domain
Names, defined policies for adding to the registry, and made some
suggestions about how those policies might be implemented. Since the
publication of RFC 6761, the IETF has been asked to designate several
new Special-Use Domain Names in this registry. During the evaluation
process for these Special-Use Domain Names, the IETF encountered several
different sorts of issues. 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 should be deprecated. The IETF DSNOP working
group charter was extended to include conducting a review of the process
for adding names to the registry that is defined in RFC 6761. This
document is a product of that review.
Based on current ICANN and IETF practice, including RFC 6761, there
are several different types of names in the root of the Domain
Namespace:
Reserved by the IETF for technical purposes
Assigned by ICANN to the public DNS root; some names reserved by
the IETF for technical purposes may appear in the Global DNS root
for reasons pertaining to the operation of the DNS
ICANN Reserved Names; names that may not be applied for as TLDs
(see , Section 2.2.1.2.1, Reserved
Names, Section 2.2.1.4.1, Treatment of Country or Territory Names,
et al.)
Used by other organizations without following established
processes
Names that are unused and are available for assignment to one of
the previous categories
This document presents a list, believed to be complete, of the
problems associated with the assignment of Special-Use Domain Names. In
support of its analysis of the particular set of issues described here,
the document also includes descriptions of existing practice as it
relates to the use of domain names, a brief history of domain names, and
some observations by various IETF participants who have experience with
various aspects of the current situation.
This document uses the terminology from RFC
7719. Other terms used in this document are defined here:
This document uses the term "Domain Name"
as defined in section 2 of RFC
7719.
The set of all possible Domain
Names.
A Domain Name listed in the
Special-Use Domain Names registry .
For the sake of brevity this document uses some abbreviations, which
are expanded here:
Internet Assigned Numbers Authority
Internet Corporation for Assigned Names and
Numbers
Top-Level Domain, as defined in section 2 of RFC 7719
Generic Top-Level Domain (see section 2 of
RFC 2352)
This section presents a list of problems that have been identified
with respect to the assignment of Special-Use Domain Names. Solutions to
these problems, including their costs or tradeoffs, are out of scope for
this document. They will be covered in a separate document. New problems
that might be created in the process of solving problems described in
this document are also out of scope: these problems are expected to be
addressed in the process of evaluating potential solutions.
Special-Use Domain Names exist to solve a variety of problems. This
document has two goals: enumerate all of the problems that have been
identified to which Special-Use Domain Names are a solution and
enumerate all of the problems that have been raised in the process of
trying to use RFC 6761 as it was intended. As some of those problems may
fall into both categories, this document makes no attempt to categorize
the problems.
There is a broad diversity of opinion about this set of problems. Not
every participant agrees that each of the problems enumerated in this
document is actually a problem. This document takes no position on the
relative validity of the various problems that have been enumerated, nor
on the organization responsible for addressing each individual problem,
if it is to be addressed. The sole purposes of the document are to
enumerate those problems, provide the reader with context for thinking
about them and provide a context for future discussion of solutions,
regardless of whether such solutions may be work for IETF, ICANN, IANA
or some other group.
This is the list of problems:
No formal coordination process exists between the IETF and ICANN
as they follow their respective name assignment processes (see ). The lack of coordination complicates the management
of the root of the Domain Namespace and could lead to conflicts in name
assignments .
There is no explicit scoping as to what can constitute a "technical use" and what cannot, and there
is also no consensus within the IETF as to what this term means.
Not all developers of protocols on the internet agree that
authority over the entire Domain Namespace should reside solely with
the IETF and ICANN.
Although IETF and ICANN nominally have authority over this
namespace, neither organization can enforce that authority over any
third party who wants to just start using a subset of the namespace.
Such parties may observe that the IETF has never asserted control or
authority over what protocols are "allowed" on the internet, and
that the principle of "permissionless innovation" suggests there
should be a way for people to include new uses of domain names in
new protocols and applications.
Organizations do in fact sometimes use subsets of the Domain
Namespace without following established processes. Reasons a third
party might do this include:
Unaware that a process exists for assigning such names
Intended use is covered by gTLD process , but no gTLD process is ongoing
Intended use is covered by gTLD process, but the third party
doesn't want to pay a fee
Intended use is covered by some IETF process, but the third
party doesn't want to follow the process
Intended use is covered by ICANN or IETF process, but third
party expects that the outcome will be refusal or non-action
Unaware that a name intended to be used only locally may
nevertheless leak
Unaware that a name used locally with informal allocation may
subsequently be allocated formally, creating operational
problems
There is demand for more than one name resolution protocol for
Domain Names. Domain Names contain no metadata to indicate which
protocol to use to resolve them. Domain name resolution APIs do not
provide a way to specify which protocol to use.
When a Special-Use Domain Name is added to the Special-Use Domain
Names registry, not all software that processes such names will
understand the special use of that name. In many cases, name
resolution software will use the Domain Name System for resolution
of names not known to have a special use. Consequently, any such use
will result in queries for Special-Use Domain Names being sent to
Domain Name System authoritative servers. These queries may
constitute an operational problem for operators of root zone
authoritative name servers. These queries may also inadvertently
reveal private information through the contents of the query, which
is a privacy consideration.
The RFC 6761 process is sufficiently uncertain that some protocol
developers have assumed they could not get a name assigned; the
process of assigning the first new name ('.local') using the RFC
6761 process took more than ten years from beginning to end: longer
by a factor of ten than any other part of the protocol development
process (largely because this ten years included time to develop the
process as well as use it). Other uses of the process have proceeded
more smoothly, but there is a reasonably justified perception that
using this process is likely to be slow and difficult, with an
uncertain outcome.
There is strong resistance within the IETF to assigning Domain
Names to resolution systems outside of the DNS, for a variety of
reasons:
Requires a mechanism for identifying which of a set of
resolution processes is required in order to resolve a
particular name.
Assertion of authority: there is a sense that the Domain
Namespace is "owned" by the IETF or by ICANN, and so, if a name
is claimed outside of that process, the person or entity that
claimed that name should suffer some consequence that would,
presumably, deter future circumvention of the official
process.
More than one name resolution protocol is bad, in the sense
that a single protocol is less complicated to implement and
deploy.
The semantics of alternative resolution protocols may differ
from the DNS protocol; DNS has the concept of RRtypes; other
protocols may not support RRtypes, or may support some entirely
different data structuring mechanism.
If there is an IETF process through which a TLD can be
assigned at zero cost other than time, this process will be used
as an alternative to the more costly process of getting the name
registered through ICANN.
A name might be assigned for a particular purpose when a more
general use of the name would be more beneficial.
If the IETF assigns a name that some third party or parties
believes belongs to them in some way, the IETF could become
embroiled in an expensive dispute with those parties.
If there were no process for assigning names for technical use
through the IETF, there is a concern that protocols that require
such names would not be able to get them.
In some cases where the IETF has made assignments through the RFC
6761 process, technical mistakes have been made due to
misunderstandings as to the actual process that RFC 6761 specifies
(e.g., treating the list of suggested considerations for assigning a
name as a set of requirements all of which must be met). In other
cases, the IETF has made de facto assignments of Special-Use Domain
Names without following the RFC 6761 process.
There are several Domain Name TLDs that are in use without due
process for a variety of purposes. The status of these names need to
be clarified and recorded to avoid future disputes about their use
.
In principle, the RFC 6761 process could be used to document the
existence of Domain Names that are not safe to assign, and provide
information on how those names are used in practice. However,
attempts to use RFC 6761 to accomplish this documentation have not
been successful (for example, see "Additional Reserved Top Level
Domains and
). One side effect of the lack of
documentation is that any mitigation effect on the root name servers
or on privacy considerations has been missed.
A Domain Name can be identified as either a DNS name by placing
it in the DNS zone(s) or as a Special-Use Domain Name by adding it
to the IANA registry. Some names are in both places; for example,
some locally served zone names are in DNS zones and documented in
the Special-Use Domain Names registry. At present, the only way a
Domain Name can be added to the Special-Use Domain Name registry is
for the IETF to take responsibility for the name and designate it
for "technical use". There are other potential uses for Domain Names
that should be recorded in the registry, but for which the IETF
should not take responsibility.
The IETF may in some cases see the need to document that a name
is in use without claiming that the use of the name is the IETF's
use of the name. No mechanism exists in the current registry to mark
names in this way.
There is no formal process during any of the review stages for a
document in which a check is made to ensure that the document does
not unintentionally violate IETF process for adding special-use
domain names to the registry, as was the case, for example, in RFC
7788 .
Use of the registry is inconsistent -- some Special-Use Domain
Name RFCs specify registry entries, some don't; some specify
delegation, some don't.
There exists no safe, non-process-violating mechanism for ad-hoc
assignment of Special-Use Domain Names.
It is generally assumed that protocols that need a Special-Use
Domain Name need a mnemonic, single-label, human-readable
Special-Use Domain Name, for use in user interfaces such as command
lines or URL entry fields. While this assumption is correct in some
cases, it is likely not correct in all cases; for example, in
applications where the DNS name is never visible to a user.
RFC 6761 uses the term "Domain Name" to describe the thing for
which special uses are registered. This creates a great deal of
confusion because some readers take "Domain Name" to imply the use
of the DNS protocol.
The use of DNSSEC with Special-Use Domain Names is an open issue.
There is no consensus or guidance about how to use DNSSEC with
various classes of Special-Use Domain Names. Considerations in the
use of DNSSEC with Special-Use Domain Names include:
What class of Special-Use Domain Name is under consideration:
non-DNS, locally served zone, other?
Does the Special-Use Domain Name require a delegation in the
root zone; if so, should that delegation be signed or not? If
there is no delegation, then this will be treated by validating
resolvers as a secure denial of existence for that zone. This
would not be appropriate for a name being resolved using the DNS
protocol.
A process would be required through which the IETF can cause
a delegation in the root zone to be instantiated.
What are the recommended practices for using DNS with the
specific Special-Use Domain Name?
The problems we have stated here represent the current understanding
of the authors of the document as to the complete set of problems that
have been identified during discussion by the working group on this
topic. The remainder of this document provides additional context that
will be needed for reasoning about these problems.
There are three primary (see ) and
numerous secondary () documents to consider
when thinking about the Special-Use Domain Names process.
How names are resolved is ambiguous, in the sense that some names are
Special-Use Domain names that require special handling, and some names
can be resolved using the DNS protocol with no special handling.
The assignment of Internet Names is not under the sole control of any
one organization. IETF has authority in some cases, but only with
respect to "technical uses." ICANN at present is the designated
administrator of the root zone, but generally not of zones other than
the root zone. Neither of these authorities can in any practical sense
exclude the practice of ad-hoc use of names. Unauthorized use of domain
names can be accomplished 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 operates. It can also be accomplished by authors of
software who decide that a Special-Use Domain Name is the right way to
indicate the use of an alternate resolution mechanism.
The primary documents are considered primary because they directly
address the IETF's past thoughts on this topic in a general way, and
also because they describe what the IETF does in practice. Only one of
these documents is an IETF consensus document.
This document is not an IETF
consensus document, and appears to have been written to address a
different problem than the Special-Use Domain Name problem. However,
it speaks directly to several of the key issues that must be
considered, and, coming as it does from the IAB, it is rightly
treated as having significant authority despite not being an IETF
consensus document.
This document should be considered required reading for IETF
participants who wish to express an informed opinion on the topic of
Special-Use Domain Names. The main points that appear relevant to
the Special-Use Domain Names problem are:
The Internet requires a globally unique namespace: a
namespace in which any given name refers to the same information
(has the same meaning) no matter who requests that information
and no matter from which specific name server they request
it.
Private networks may operate private namespaces, with names
that have meanings only locally (within the private network) but
still require that names in the public namespace be globally
unique.
The Domain Name System is not
the only protocol that may be used for resolving domain
names.
Users cannot be assumed to know how to distinguish between
symbolic references that have local meaning and references that
have global meaning. Users may therefore share references that
incorporate Domain Names with no global meaning (for example, a
URL of 'http://mysite.example.corp', where 'example.corp' is a
domain used privately and informally as described in ).
Such references might refer to the object the user intends to
share within that user's context, but either refer to some other
object any recipient's context, or might not refer to any object
at all in a recipient's context. The effect of this reference
escaping the context in which it is valid is that the user's
intended communication will not be able to be understood by the
recipients of the communication.
This same problem can also occur when a single user copies a
name from one context in which it has one meaning, into a
different context in which it has a different meaning -- for
example copying a '.onion' Domain Name out of a Tor Browser
, where it has meaning, and pasting this
name into an ssh client that doesn't support connecting over the
Tor network.
We can summarize the advice in this document as follows:
Domain Names with unambiguous global meaning are preferable
to Domain Names with local meaning which will be ambiguous.
Nevertheless both globally-meaningful and locally-special names
are in use and must be supported.
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 protocol used to resolve Domain Names.
The second important document is
"Special-Use Domain Names". RFC 6761 represents the current
IETF consensus on designating and recording Special-Use Domain
Names. The IETF has experienced problems with the designation
process described in RFC 6761; these concerns motivate this
document. Familiarity with RFC 6761 is a prerequisite for having an
informed opinion on the topic of Special-Use Domain Names.
RFC 6761 defines two aspects of Special-Use Domain Names:
designating a Domain Name to have a special purpose and registering
that special use in the Special-Use Domain Names registry. The
designation process is defined in a single sentence (RFC 6761,
section 4):
If it is determined that special handling of a name is
required in order to implement some desired new functionality,
then an IETF "Standards Action" or "IESG Approval" specification
[RFC5226] MUST be published describing the new
functionality.
This sentence requires that any designation of a Special-Use
Domain Name is subject to the same open review and consensus process
as used to produce and publish all other IETF specifications.
The registration process is a purely mechanical process, in which
the existence of the newly designated Special-Use Domain Name is
recorded, with a pointer to a section in the relevant specification
document that defines the ways in which special handling is to be
applied to the name.
RFC 6761 provided the process whereby
Multicast DNS designated ".local" as a Special-Use Domain
Name and included it in the Special-Use Domain Names registry. It
itself also enumerated a set of names that had been previously used
or defined to have special uses prior to the publication of RFC
6761. Since there had been no registry for these names prior to the
publication of RFC 6761, the documents defining these names could
not have added them to the registry.
There are at least several important points to think of with
respect to the RFC 6761:
A Special-Use Domain Name may be a name that should be
resolved using the DNS protocol with no special handling. An
example of this is 'IN-ADDR.ARPA.' (which is an example of a
Special-Use Domain Name that is not a TLD).
A Special-Use Domain Name may be a name that is resolved
using the DNS protocol, requires no special handling in the stub
resolver, but requires special handling in the recursive
resolver. An example of this would be "10.in-addr.arpa."
A Special-Use Domain Name may be a name that requires special
handling in the stub resolver. An example would be a Special-Use
Top-Level Domain Name like '.local' which acts as a signal to
indicate that the local stub resolver should use a non-DNS
protocol for name resolution.
The current IETF consensus (from a process perspective, not
necessarily from the perspective of what would be consensus if
the IETF were to attempt to produce a new consensus document) is
that all of these purposes for Special-Use Domain Names are
valid.
The term "stub resolver" in this case does not mean "DNS protocol
stub resolver." The stub resolver is the entity within a particular
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
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
so which protocol, or whether to use a local database of some sort,
is made.
RFC 6761 does not limit Special-Use Domain Names to TLDs.
However, at present, all Special-Use Domain Names registered in the
IANA Special-Use Domain Names
registry are either intended to be resolved using the DNS
protocol, or are TLDs, or both. That is, at present there exist no
Special-Use Domain Names which require special handling by stub
resolvers and which are not at the top level of the naming
hierarchy.
One point to take from this is that there is already a
requirement in RFC 6762 that when stub resolvers encounter the
special label, '.LOCAL' at the top level of a domain name, they can
only use the mDNS protocol be used for resolving that Domain
Name.
There exists a Memorandum of Understanding between the IETF and ICANN (Internet Corporation
for Assigned Names and Numbers) which discusses how names and
numbers will be managed through the IANA (Internet Assigned Numbers
Authority). This document is important to the discussion of
Special-Use Domain Names because, while it delegates authority for
managing the Domain Name System Namespace generally to ICANN, it
reserves to the IETF the authority that RFC 6761 formalizes:
Note that (a) assignments of Domain Names for technical uses
(such as Domain Names for inverse DNS lookup), (b) assignments
of specialised 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 above text is an addendum to the following:
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
blocks. These policy issues are outside the scope of this
MOU.
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 by ICANN. However, the MoU specifically exempts domain
names 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 Special-Use Domain Names registry.
Implicit in the MoU is the fact that the IETF and ICANN retain,
between them, sole authority for assigning any names from the Domain
Namespace. Both the IETF and ICANN have internal processes for
making such assignments.
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 existence of this statement.
As a result of processing requests to add names to the
Special-Use Domain Name registry, as documented in and , a review was
chartered of the process defined in RFC 6761 for adding names to the
registry (as explained earlier). The Liaison Statement notified ICANN of the review, affirmed
that the discussion would be "open and transparent to participation
by interested parties" and explicitly invited members of the ICANN
community to participate.
In addition to these documents, there are several others with which
participants in this discussion should be familiar.
Multicast DNS defines the Multicast DNS
protocol, which uses the '.LOCAL' Special-Use Top-Level Domain Name.
Section 3 describes the semantics of "multicast DNS names." It is of
considerable historical importance to note that the -00 version of
this document, an individual submission, was published in July of
2001. This version contains substantially the same text in section
3, and was discussed in the DNSEXT working group at IETF 51 in
August of 2001. The first version of
this document designated '.LOCAL.ARPA' as the Special-Use Domain
Name. This idea was strongly opposed by DNSEXT working group
participants, and as a result the author eventually switched to
using '.LOCAL'.
The history of RFC 6762 is documented in substantial detail in
Appendix H of RFC 6762; some notable milestones include the initial
proposal to replace Appletalk's NBP in July 1997, the chartering of
the Zeroconf working group in September 1999, assignment of a
multicast address for link-local name discovery in April of 2000. A
companion requirements document, eventually published as was first published in September of 2001.
The point of mentioning these dates is so that discussions
involving the time when the '.LOCAL' domain was first deployed, and
the context in which it was deployed, may be properly informed.
The .onion Special-Use Top-Level Domain
Name is important because it is the most recent IETF action
on the topic of Special-Use Domain Names; although it does not set
new policy, the mere fact of its publication is worth thinking
about.
Two important points to consider about this document are that:
The IETF gained consensus to publish it
The situation was somewhat forced, both by the fact of its
unilateral use by The Tor Project without following the RFC 6761
process, and because a deadline had
been set by the CA/Browser Forum after which all .onion
PKI certificates would expire and no new certificates would be
issued, unless the .onion Special-Use Top-Level Domain Name were
to be recognized by the IETF.
Locally Served DNS Zones describes
a particular use case for zones that exist by definition, and that
are resolved using the DNS protocol, but that cannot have a global
meaning, because the host IP addresses they reference are not
unique. This applies to a variety of addresses, including Private IPv4 addresses, Unique Local IPv6 Unicast Addresses (in
which this practice was first described) and IANA-Reserved IPv4 Prefix for Shared Address
Space.
This use case is distinct from the use-case for Special-Use
Domain Names like '.local' and '.onion' in that the names are
resolved using the DNS protocol (but do require extensions or
exceptions to the usual DNS resolution to enforce resolution in a
local context rather than the global DNS 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.
Name Collision in the DNS is
a study commissioned by ICANN that attempts to characterize the
potential risk to the Internet of adding global DNS delegations for
names that were not 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 Special-Use-type reasons (local scope
DNS, or other resolution protocols altogether).
ICANN SSAC () Advisory on the
Stability of the Domain Namespace
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.
Discovery of the IPv6 Prefix Used for IPv6
Address Synthesis is an example of a document that
successfully used the RFC 6761 process to designate '.ipv4only.arpa'
as a Special-Use Domain Name; in this case the process worked
smoothly and without controversy.
Unfortunately, while the IETF process worked smoothly, in the
sense that there was little controversy or delay in approving the
new use, it did not work correctly: the name "ipv4only.arpa" was
never added to the Special-Use Domain Names registry. This appears
to have happened because the document did not explicitly request the
addition of an entry for "ipv4only.arpa" in the SUDN registry. This
is an illustration of one of 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.
Additional
Reserved Top Level Domains is an example of a document that
attempted to reserve several TLDs identified by ICANN as
particularly at risk for collision as Special-Use Domain Names with
no documented use. This attempt failed.
Although this document failed to gain consensus to publish, the
need it was intended to fill still exists. Unfortunately, although a
fair amount is known about the use of these names, no RFC documents
how they are used, and why it would be a problem to delegate them.
Additionally, to the extent that the uses being made 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.
RFC 7788 defines the Domain Name TLD
".home" for use as the default name for name resolution relative to
a home network context. Although, as defined in RFC 7788, ".home" is
a Special-Use Domain Name, RFC 7788 did not follow the process
specified in RFC 6761: it did not request that ".home" be added to
the IANA Special-Use Domain Name registry. This was recognized as a
mistake, and resulted in the publication of an errata, . Additionally, ".home" is an example of an
attempt to reuse a Domain Name that has already been put into use
for other purposes without following established processes, which further complicates the situation.
At the time this document was written, the IETF was developing a
solution to this problem.
Newcomers to the problem of resolving Domain Names may be under the
mistaken impression that the DNS sprang, as in the Greek legend of
Athena, directly from Paul Mockapetris' forehead. This is not the case.
At the time of the writing of the IAB technical document, memories would
have been fresh of the evolutionary process that led to the DNS'
dominance as a protocol for Domain Name resolution.
In fact, in the early days of the Internet, hostnames were resolved
using a text file, HOSTS.TXT, which was maintained by a central
authority, the Network Information Center, and distributed to all hosts
on the Internet using the File Transfer Protocol
(FTP). The inefficiency of this process is cited as a reason for
the development of the DNS in 1983.
However, the transition from HOSTS.TXT to the DNS was not smooth. For
example, Sun Microsystems's Network
Information System, at the time known as Yellow Pages, was an
active competitor to the DNS, although it failed to provide a complete
solution to the global naming problem.
Another example was NetBIOS Name Service, also known as WINS . This protocol was used mostly by Microsoft Windows
machines, but also by open source BSD and Linux operating systems to do
name resolution using Microsoft's own name resolution protocol.
Most modern operating systems can still use the '/etc/hosts' file for
name resolution. Many still have a name service switch that can be
configured on the host to resolve some domains using NIS or WINS. Most
have the capability to resolve names using mDNS by recognizing the
special meaning of the '.local' Special-Use Top Level Domain Name.
The Sun Microsystems model of having private domains within a
corporate site, while supporting the global Domain Name system for
off-site, persisted even after the NIS protocol fell into disuse.
Microsoft used to recommend that site administrators use a "private" TLD
for internal use, and this practice was very much a part of the
zeitgeist at the time (see section 5.1 of and Appendix G of ).
This attitude is at the root of the widespread practice of simply
picking an unused TLD and using it for experimental purposes, which
persists even at the time of writing of this memo.
This history is being presented because discussions about Special-Use
Domain 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
using some other naming concept that doesn't overlap with the namespace
that, in modern times is, by default, resolved using the DNS.
The answer is that as a consequence of this long history of resolving
Domain Names using a wide variety of name resolution systems, Domain
Names are required in a large variety of contexts in user interfaces and
applications programming interfaces. Any name that appears in such a
context is a Domain Name. So developers of new name resolution systems
that must work in existing contexts actually have no choice: they must
use a Special-Use Domain Name to segregate a portion of the namespace
for use with their system.
This document mentions various security and privacy considerations in
the text. However, this document creates no new security or privacy
concerns.
This document has no actions for IANA.
This document came about as a result of conversations that occurred
in the conference hotel lobby, the weekend before IETF 95, when the
original author, Ted Lemon, was trying to come up with a better problem
statement. Stuart Cheshire, Mark Andrews, David Conrad, Paul Ebersman
and Aaron Falk all made helpful and insightful observations or patiently
answered questions. This should not be taken as an indication that any
of these folks actually agree with what the document says, but their
generosity with time and thought are appreciated in any case.
Ralph started out as an innocent bystander, but discussion with him
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 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 work got
finished; without him the -01 and -02 versions might not have
happened.
This document also owes a great deal to Ed Lewis' excellent work on
what a "Domain Name"
is.
Guidance on the Deprecation of Internal Server Names and
Reserved IP Addresses
CA/Browser Forum
Name Collisions in the DNS
Interisle Consulting Group, LLC
SSAC Advisory on the Stability of the Domain
Namespace
ICANN Security and Stability Advisory
Committee
SSAC Advisory on the Stability of the Domain
Namespace
ICANN Security and Stability Advisory
Committee
Special-Use Domain Names registry
Internet Assigned Numbers Authority
Special-Use Domain Names registry
Internet Assigned Numbers Authority
Liaison Statement from the IAB to the ICANN Board on
Technical Use of Domain Names
Internet Architecture Board
Errata ID: 4677 (RFC7788)
Internet Architecture Board
Large System and Network Administration
Sun Microsystems
Proceedings of the 51st IETF
Internet Engineering Task Force
Tor
The Tor Project
-03 to -04:
Issue #72: Corrected original text to reflect that RFC 7050
neglected to request an SUDN registry entry for "ipv4only.arpa", but
any inference about the cause for the oversight would be
speculation.
Issue #69: Edited Joel's suggested text.
Issue #67: Minor change to Joel's suggested text.
Issue #66: Edited second text update suggested by Joel and
reverted third change back to the original text.
Issue #64: Minor changes to text suggested by Joel.
Issue #61: Minor edit based on authors' consensus in response to
Joel's comment.
Addressed Joel / Benoit's AD comments. See GH issues
-02 to -03 (in Github):
Passes idnits except for errors resulting from a reference to an
RFC 2119 keyword and a citation of RFC 5226 with no matching
reference in quoted text at line 493.
Issue #60: Add new section "6. Summary" -- Petr Spacek
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/60
Issue #57: Document needs an "Security Considerations" section
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/57
Numerous editorial changes for consistency; e.g. use "Special-Use
Domain Names" throughout.
Issue #58: Document needs an "IANA Considerations" section
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/58
Issue #39: Overlapping bullets in Section 3, with proposed
restructuring -- Russ Housley
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/39
Issue #55: Editorial improvement to Section 3 (4) -- John
Dickinson
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/55
Issue #34: Separate two problems in paragraph that begins "No
mechanism exists for adding a name to the registry...." (2 issues)
-- Suzanne Woolf
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/34
Issue #52: Editorial improvement to Section 3 (1) -- John
Dickinson
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/52
Issue #51: Clarification in Introduction -- John Dickinson
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/51
Issue #49: Should cite https://datatracker.ietf.org/liaison/1351
-- George Michaelson
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/49
Issue #50: IETF precedence in Special-Use names registry -- Ted
Lemon
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/50
Issue #48: 4.1.2 cites sub-domains of .ARPA arguing for special
use TLD -- George Michaelson
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/48
Issue #47: 4.3 should be made more prominent -- George Michaelson
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/47
Issue #43: Spell out SUDN and SUTLDN rather than use acronyms --
Russ Housley
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/43
Issue #41: Reword bullet in Section 3 regarding Domain Name TLDs
that have been commandeered, as reported in SDO-ICANN-COLL -- Russ
Housley
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/41
Issue #40: Note that time to publish spec for .local included
inventing SUDN registry -- Russ Housley
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/41
Issue #37: Title should be "Special-Use Domain Names Problem
Statement" -- Russ Housley
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/37
Issue #36: Expand on desire for Special-Use names to be
human-readable -- Suzanne Woolf
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/36
Issue #35: Clarify "No process exists [...]" to include both IETF
process and other process -- Suzanne Woolf
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/35
Issue #31: Add justification for concern about IETF's ability to
assign names for technical use -- Suzanne Woolf
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/31
Issue #12: Add DNSSEC to text -- John Levine
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/12
Issue #6: Without a process, we just have chaos -- Stuart
Cheshire
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/6
Issue #32: Have assignments through RFC 6761 really had
"technical mistakes"? -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/32
Issue #29: Add a reason to bypass external process: expectation
for use of new name to be restricted to local scope -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/29
Issue #27: Is "technical use" really ambiguous; too inclusive for
some people and too limited for others -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/27
Issue #24: Replacement for "commandeer" (2 issues)-- Suzanne
Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/24
Issue #22: Clarify importance of the "root of the Domain
Namespace" -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/22
Issue #21: Section 3 - clarify paragraphs 2 and 3 -- Suzanne
Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/21
Issue #20: Section 3: Clarify sentences beginning "Solutions to
these problems..." -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/20
Issue #19: Define "default" or "assumed" use of domain names to
be within DNS -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/19
Issue #18: Cite definition of RFC 7719 and domain names draft in
definition of "domain name" -- Suzanne Wolff
https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/18
Issue #45: Correct usages of Tor Browser and Tor -- Russ Housley
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/45)
Issue #46: Reformat citation of RFC 2860 -- Russ Housley
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/46)
Issue #44: Clean up reference to SDO-ICANN-DAG in first bullet in
section 3 -- Russ Housley
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/44)
Issue #42: Add reference to SDO-ICANN-SAC090 in section 4.2.5 --
Russ Housley
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/42)
Issue #30: Leaked queries aren't an operational problem in
practice -- Suzanne Wolf
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/30)
Address some of the simpler issues, including:
Issue #13: Spelling of Tor -- Jeremy Rand
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/13)
Issue #14: Change SDO to "organizations" -- Suzanne Woolf
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/14)
Issue #16: Match number of "policies" and "that policy" --
Suzanne
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/16)
Issue #17: Clarify sentence beginning with "In support of the
particular set of problems described here...." -- Suzanne.
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/14)
Issue #23: Match number of "names" and "a TLD" -- Suzanne.
(https://github.com/Abhayakara/draft-tldr-sutld-ps/issues/23)
-01 to -02:
Language cleanup from Ted.
-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:
Replaced 'Internet Names' with 'Domain Names' - suggestion by
John Levine.
-02 to -03:
Readability fixes, small grammar updates.
-01 to -02:
Cleaned up the abstract.
Fixed the case of Internet
Reference to Ed Lewis' "Domain Names"
Fleshed out the problems, primarily the coordination, collisions
ones.
-00 to -01:
Large refactoring, basically a rewrite. Incorporated comments,
removed a bunch of unneeded text, etc.