Internet DRAFT - draft-chapin-rfc2606bis
draft-chapin-rfc2606bis
Network Working Group L. Chapin
Internet-Draft Interisle Consulting Group
Intended status: Standards Track M. McFadden
Expires: December 2, 2011 ICC
May 31, 2011
Reserved Top Level Domain Names
draft-chapin-rfc2606bis-00.txt
Abstract
The Internet Domain Name System (DNS) defines a tree of names
starting with root, ".", immediately below which are top level domain
(TLD) names such as ".com" and ".us". RFC2606 reserved a small
number of TLD names for use in documentation examples, private
testing, experiments, and other circumstances in which it is
desirable to avoid conflict with current or future actual TLD names
in the DNS. The evolution of Internet engineering and operation
practices since RFC2606 was published in 1999, and the expected
addition of new TLD names to the DNS, recommend this update to the
list of reserved TLD names, and the creation of a "reserved TLD name
registry" to which additional names may be added as new requirements
arise.
It is important to note that TLD names may be reserved, in other
contexts, for policy, political, or other reasons that are distinct
from the IETF's concern with Internet engineering and operations.
This document reserves TLD names only for operational and engineering
reasons.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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 December 2, 2011.
Chapin & McFadden Expires December 2, 2011 [Page 1]
Internet-Draft Reserved Top Level Domain Names May 2011
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Legacy Reserved Top Level Domain Names . . . . . . . . . . . . 4
3. Additional Reserved Top Level Domain Names and Reserved
TLD Name Registry . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IAB Considerations . . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
8. Appendix - Initial Registry of Reserved Top Level Domain
Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9. Normative References . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapin & McFadden Expires December 2, 2011 [Page 2]
Internet-Draft Reserved Top Level Domain Names May 2011
1. Introduction
The Internet Domain Name System is documented in RFC1034 [1], RFC1035
[2], RFC1591 [3] and numerous additional Requests for Comment. It
defines a tree of names starting with root, ".", immediately below
which are top level domain names such as ".com" and ".us". Below top
level domain names there are normally additional levels of names.
RFC2606 [5] reserved a small number of TLD names which, without fear
of conflicts with current or future actual top level domain names in
the global DNS, can be used for private testing of existing DNS
related code, examples in documentation, DNS related experimentation,
invalid DNS names, or other similar uses. RFC2606 [5] also noted
that the Internet Assigned Numbers Authority (IANA) reserves the
label "example" at the second level below the TLDs .com, .net, and
.org.
Since RFC2606 [5] was published in 1999, Internet engineering and
operation practices have evolved in ways that recommend this update
to the list of reserved TLD names, and the creation of a "reserved
TLD name registry" to which additional labels may be added as new
requirements arise. This update is also prompted by the expected
advent of new TLDs which might, in the absence of the reservations
for which this document provides, introduce TLD labels that could
create engineering and operational problems for root server operators
and other DNS infrastructure providers.
It is important to note that TLD names may be reserved, in other
contexts, for policy, political, or other reasons that are distinct
from the IETF's concern with Internet engineering and operations.
This document reserves TLD names only for operational and engineering
reasons.
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 [4].
Chapin & McFadden Expires December 2, 2011 [Page 3]
Internet-Draft Reserved Top Level Domain Names May 2011
2. Legacy Reserved Top Level Domain Names
The four top level domain name labels reserved by RFC2606 [5] for
testing and documentation examples remain reserved:
o test
o example
o invalid
o localhost
".test" is recommended for use in testing of current or new DNS
related code.
".example" is recommended for use in documentation or as examples.
".invalid" is intended for use in online construction of domain names
that are sure to be invalid and which it is obvious at a glance are
invalid.
The ".localhost" TLD has traditionally been statically defined in
host DNS implementations as having an A record pointing to the loop
back IP address and is reserved for such use. Any other use would
conflict with widely deployed code which assumes this use.
This document makes no changes to the IANA reservation of the label
"example" at the second level.
Chapin & McFadden Expires December 2, 2011 [Page 4]
Internet-Draft Reserved Top Level Domain Names May 2011
3. Additional Reserved Top Level Domain Names and Reserved TLD Name
Registry
In its report of a quantitative study of queries to the DNS root
servers entitled "Invalid Top Level Domain Queries at the Root Level
of the Domain Name System" [7] [or, SAC 045] ICANN's Security and
Stability Advisory Committee "calls attention to the potential
problems that may arise should a new TLD applicant use a string that
has been seen with measurable (and meaningful) frequency in a query
for resolution by the root system and the root system has previously
generated a response."
Of particular concern is the case in which a string "has been queried
and a root name server has responded to the query with a non-existent
domain (NXDOMAIN) result, i.e., the string has not been delegated but
has been queried." SAC 045 reports the results of a CAIDA
measurement study [8] which found that "NXDOMAIN responses account
for more than 25 percent of the total responses from root name
servers observed in the study, and the top ten such strings account
for 10 percent of the total query load."
SAC 045 [7] describes in detail the engineering and operational
problems that would ensue from the delegation, as new valid TLD
names, of previously invalid labels that have frequently appeared in
queries to the root: "If the [new TLD label] were to be approved and
the TLD included in the root zone, queries to the root level of the
DNS for a string that hitherto returned NXDOMAIN would begin to
return positive responses containing name servers of the new TLD."
Recommendation (2) of SAC 045 [7] calls for the community to develop
principles for "prohibiting the delegation of additional strings to
those already identified in RFC2606 [5]." As the first step in that
process, based on the data reported by SAC 045 [7], this document
adds to the list of names that may not be used for top-level domains
the following labels:
.local
.localdomain
.domain
.lan
.home
.host
Chapin & McFadden Expires December 2, 2011 [Page 5]
Internet-Draft Reserved Top Level Domain Names May 2011
.corp
To facilitate the further steps that may be taken to pursue
Recommendation (2) of SAC 045 [7], IANA is requested to publish a new
registry of TLD names reserved by the IETF. This Reserved TLD Name
Registry should simply list the reserved TLD names with a reference
in each case to the authority for reserving the name. New names may
be added to the registry through "IETF Specification Required" as
provided by RFC4234 [6]. The initial contents of the registry are
the names listed in Appendix A of this document.
Chapin & McFadden Expires December 2, 2011 [Page 6]
Internet-Draft Reserved Top Level Domain Names May 2011
4. Security Considerations
One of the reasons cited in Section 1 for reserving specific labels
that cannot be used for valid top level domain names in the global
DNS is to make it possible for those labels to be used safely in
other contexts, without risk of conflict with "real" domain names.
Reserving these labels therefore effectively encourages their use in
locally-defined domain names that may resolve differently in
different local contexts. An application that looks up "foo.local"
on private network A, for example, may get a different result if it
looks up "foo.local" on private network B.
A name that resolves differently depending on where the lookup
request is made presents obvious security issues for any application
that does not expect this behavior. These issues arise from the use
of any locally-defined labels in domain names, whether or not they
are reserved.
Chapin & McFadden Expires December 2, 2011 [Page 7]
Internet-Draft Reserved Top Level Domain Names May 2011
5. IAB Considerations
There are no architectural implications related to reserving
individual strings at the top level of the DNS.
Chapin & McFadden Expires December 2, 2011 [Page 8]
Internet-Draft Reserved Top Level Domain Names May 2011
6. IANA Considerations
According to RFC2606 [5], IANA agreed to the top level domain
reservations in that document. However, IANA was not instructed to
publish a list of reserved names.
IANA is requested to publish a new registry of TLD strings reserved
by the IETF. The Reserved TLD Name registry will consist of a list
of reserved TLD names and a reference for each entry to the document
that put the strings into reserved status.
New strings are to be added to the registry through "IETF
Specification Required" as provided by RFC4234 [6]. The initial
content of the full registry is located in the Appendix to this
document.
Chapin & McFadden Expires December 2, 2011 [Page 9]
Internet-Draft Reserved Top Level Domain Names May 2011
7. Acknowledgements
Several studies have shown that a large fraction of the lookup
queries seen by the DNS root servers request information about
invalid TLDs. THe authors thank CAIDA, and in particular kc claffy,
for their work in this area. The authors are also indebted to the
contributors to SAC 045 which provided the impetus for this first
step at identifying a particular set of strings to be reserved.
David Conrad provided helpful input about potential security concerns
surrounding the reservation of strings at the root.
Chapin & McFadden Expires December 2, 2011 [Page 10]
Internet-Draft Reserved Top Level Domain Names May 2011
8. Appendix - Initial Registry of Reserved Top Level Domain Names
This is the initial registration for the registry of Reserved Top
Level Names in the DNS. The IANA is asked to use this material as
guidance for the creation of the initial registry. Future
registrations in this registry will be done through "IETF
Specification Required" as provided by RFC4234 [6].
+--------------+----------------+
| Label | Reference |
+--------------+----------------+
| .corp | RFCxxx |
| | |
| .domain | RFCxxx |
| | |
| .example | RFC2606,RFCxxx |
| | |
| .home | RFCxxx |
| | |
| .host | RFCxxx |
| | |
| .invalid | RFC2606,RFCxxx |
| | |
| .lan | RFCxxx |
| | |
| .local | RFCxxx |
| | |
| .localdomain | RFCxxx |
| | |
| localhost | RFC2606,RFCxxx |
| | |
| test | RFC2606,RFCxxx |
+--------------+----------------+
NOTE TO RFC EDITOR: The correct number of this document should be
substituted in the table above upon publication. At that time this
editing note should be deleted.
Table 1
Chapin & McFadden Expires December 2, 2011 [Page 11]
Internet-Draft Reserved Top Level Domain Names May 2011
9. Normative References
[1] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[2] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[3] Postel, J., "Domain Name System Structure and Delegation",
RFC 1591, March 1994.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[5] Eastlake, D. and A. Panitz, "Reserved Top Level DNS Names",
BCP 32, RFC 2606, June 1999.
[6] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[7] <http://www.icann.org/en/committees/security/sac045.pdf>
[8] <http://www.caida.org/publications/presentations/2009/rssac_dns/
rssac_dns.pdf>
Chapin & McFadden Expires December 2, 2011 [Page 12]
Internet-Draft Reserved Top Level Domain Names May 2011
Authors' Addresses
Lyman Chapin
Interisle Consulting Group
Phone: +1 617 686 2527
Email: lyman@interisle.net
URI: http://www.interisle.net
Mark McFadden
InterConnect Communications Ltd
Merlin House
Station Road
Chepstow NP16 5PB
UK
Phone: +1 608 628 2674
Email: markmcfadden@icc-uk.com
URI: http://www.icc-uk.com
Chapin & McFadden Expires December 2, 2011 [Page 13]
