dnsop W. Kumari
Internet-Draft Google
Intended status: Informational A. Sullivan
Expires: August 14, 2014 Dyn
February 10, 2014
The ALT Special Use Top Level Domain
draft-wkumari-dnsop-alt-tld-00
Abstract
This document reserves a string to be used as a TLD label in non-DNS
contexts. [Ed note: By now you should be wildly confused. Go read
the intro / background :-P ]
Status of This Memo
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This Internet-Draft will expire on August 14, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. The ALT namespace . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Lots of protocols and systems need to name entities, and the DNS
"standard" of a series of labels separated with dots has become
common, even in systems that are not actually part of the DNS.
This document reserves the string "ALT" (short for Alternate) as a
Special Use Domain ([RFC6761]) that should be used in the right-most
label position to signify that this name is not rooted in the DNS,
and that normal registration and lookup rules do not apply.
1.1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.2. Terminology
This document assumes familiarity with DNS terms and concepts.
Please see [RFC1034] for background and concepts.
o DNS context: The namespace administered by ICANN. This is the
namespace / context that "normal" DNS uses.
o non-DNS context: Any other / alternate namespace.
2. Background
The DNS is a tree, and so has a single root. Conventionally, a name
immediately beneath the root is called a "Top Level Domain" or "TLD".
TLDs usually delegate portions of their namespace to others, who may
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then delegate further. The hierarchical, distributed, caching nature
of the DNS has made it the primary resolution system on the Internet.
The success of the DNS means makes it a natural starting point for
systems that need to name entities in a non-DNS context. These name
resolutions occur in a namespace distinct from the DNS. A number of
good examples of these sorts of systems are documented in Special-Use
Domain Names of Peer-to-Peer Systems
[I-D.hoff-iesg-special-use-p2p-names]
In many cases, these systems build a DNS style tree parallel to the
global DNS administered by IANA. They often use a pseudo-TLD to
cause resolution in this alternate namespace, using things like
browser plugins, shims in the name resolution process, or simply
applications only use this alternate namespace.
In many cases the creators of these alternate namespaces have simply
chosen a convenient / descriptive string and started using this.
These new strings are "alternate" strings, and not actually
registered anywhere or part of the DNS. However they appear to be
TLDs, as they are the in the right-most position of a name. Issues
may arise if they are looked up in the DNS. These include:
o User confusion: If someone emails a link of the form foo.bar
.pseudo-TLD to someone who does not have the necessary software to
resolve names in the pseudo-TLD namespace, they may become
confused.
o Excess traffic hitting the DNS root. Lookups may leak out of the
pseudo-TLD namespace and end up hitting the DNS root nameservers.
o Collisions. If the pseudo-TLD is eventually delegated from the
root zone the behavior may be non-deterministic.
o Lack of success for the user's original goal.
3. The ALT namespace
In order to avoid the above issues we reserve the .ALT label. This
label should be used as a pseudo-TLD (in the right most (TLD)
position of a name) to signify that this is an alternate (non-DNS)
namespace.
Alternate namespaces should differentiate themselves from other
alternate namespaces by choosing a name and using it in the label
position just before the pseudo-TLD. For example, a group wishing
create a namespace for [TODO(?): Need something better] Friends Of
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Olaf they may choose the string "foo" and use any set of labels under
foo.alt.
As they are in an alternate namespace they have no significance in
the regular DNS context and so should not be looked up in the DNS
context. Unfortunately simply saying that "something should not
happen" doesn't actually stop it from happening, so we need some
rules to deal with these.
1. Stub resolvers MAY elect not to send queries to any upstream
resolver for names in the ALT TLD.
2. Iterative resolvers SHOULD follow the advice in [RFC6303],
Section 3.
3. The root zone nameservers should either return NXDOMAIN
responses, or the ALT TLD should be delegated to "new style"
AS112 nameservers. (TODO(WK): WK, JA, BD to revive AS112 /
AS112-bis).
Groups wishing to create alternate namespaces SHOULD create their
alternate namespace "under" a label that names their namespace, and
"under" the ALT label. They SHOULD choose a label that they expect
to be unique / descriptive. As there is no registry for the ALT
namespace uniqueness is not guaranteed.
Currently deployed projects and protocols that are using pseudo-TLDs
(for example, the ".onion" pseudo-TLD (and other labels in
[I-D.grothoff-iesg-special-use-p2p-names]) are not expected to move
under the ALT TLD (but may do so if they wish; this is a common
resource). Rather, the ALT TLD is being reserved so that future
projects of a similar nature have a designated place to create
alternate resolution namespaces that will not conflict with the
regular DNS context.
4. IANA Considerations
The IANA is requested to add the ALT string to the "Special-Use
Domain Name" registry ([RFC6761], and reference this document. In
addition, the "Locally Served DNS Zones" ([RFC6303]) registry should
be updated to reference this document.
[ Ed: There are two options here. Option 1: We could ask the IANA to
run a "First Come First Served" registry for labels under the ALT
TLD. By registry I mean a "standard" IANA registry, not a registry
in the DNS sense of the word (IANA would publish on a webpage "Foo |
fred@example.com | Used for the foo project"). Option 2: This is a
fully uncoordinated space (in the same way that people have been
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picking pseudo-TLDs up till now) -- pick something that, as far as
you know other's are not using... There are pros and cons to both --
I don't want to overload the IANA, have people stage a land-grab for
names, or give the impression that this is a "real" TLD. Thoughts?
Currently we say there is no registry (Section 3), but that can be
changed.)]
5. Security Considerations
One of the motivators for the creation of the alt pseudo-TLD is that
unmanaged labels in the managed root name space are subject to
unexpected takeover if the manager of the root name space decides to
delegate the unmanaged label.
The unmanaged and registry-free nature of labels beneath .ALT
provides the opportunity for an attacker to re-use the chosen label
and thereby possibly compromise applications dependent on the special
host name.
6. Acknowledgements
The authors understand that there is much politics surrounding the
delegation of a new TLD and thank the ICANN liaison (and any other
poor sod who gets sucked into this) in advance.
7. References
7.1. Normative References
[I-D.grothoff-iesg-special-use-p2p-names]
Grothoff, C., Wachs, M., hellekin, h., and J. Appelbaum,
"Special-Use Domain Names of Peer-to-Peer Systems", draft-
grothoff-iesg-special-use-p2p-names-01 (work in progress),
December 2013.
[IANA.AS_Numbers]
IANA, "Autonomous System (AS) Numbers",
<http://www.iana.org/assignments/as-numbers>.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6303] Andrews, M., "Locally Served DNS Zones", BCP 163, RFC
6303, July 2011.
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[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, February 2013.
7.2. Informative References
[I-D.ietf-sidr-iana-objects]
Manderson, T., Vegoda, L., and S. Kent, "RPKI Objects
issued by IANA", draft-ietf-sidr-iana-objects-03 (work in
progress), May 2011.
Appendix A. Changes / Author Notes.
[RFC Editor: Please remove this section before publication ]
From -00 to -01.
o Nothing changed in the template!
Authors' Addresses
Warren Kumari
Google
1600 Amphitheatre Parkway
Mountain View, CA 94043
US
Email: warren@kumari.net
Andrew Sullivan
Dyn
150 Dow Street
Manchester, NH 03101
US
Email: asullivan@dyn.com
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