Individual submission L-J. Liman Internet-Draft Autonomica Updates: RFC 1123 March 4, 2009 (if approved) Intended status: Standards Track Expires: September 5, 2009 Top Level Domain Name Specification draft-liman-tld-names-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 5, 2009. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Liman Expires September 5, 2009 [Page 1] Internet-Draft Top Level Domain Name Specification March 2009 Abstract RFC 1123 is ambiguous regarding the specification for top level domain (TLD) labels used in the domain name system. This document clarifies the specification, and aligns it with current praxis, including the use of Internationalized Domain Name (IDN) Labels in TLD names. Table of Contents 1. Introduction and Background . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Requirements Language . . . . . . . . . . . . . . . . . . . 3 2. Technical specification for Top Level Domain Labels . . . . . . 4 3. Other Limitations on Top Level Domain Labels . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Normative References . . . . . . . . . . . . . . . . . . . 8 6.2. Informative References . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 Liman Expires September 5, 2009 [Page 2] Internet-Draft Top Level Domain Name Specification March 2009 1. Introduction and Background RFC 1123 [RFC1123] is ambiguous regarding the specification for top level domain (TLD) labels used in the domain name system. There are different interpretations which leads to problems when deciding on new TLD names. One important aspect of this is the wish to use internationalized domain name (IDN, RFC 3490 et. al. [RFC3490]) labels in top level domains to facilitate use of local scripts. This document strives to make a new and clear definition of which character sequences are allowed in TLD labels. This document is a proposal and a work in progress. 1.1. Terminology The terminology used in this document is as defined in RFC 0952 [RFC0952] and RFC 1035 [RFC1035]. 1.2. Requirements Language 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 RFC 2119 [RFC2119]. Liman Expires September 5, 2009 [Page 3] Internet-Draft Top Level Domain Name Specification March 2009 2. Technical specification for Top Level Domain Labels RFC 952 [RFC0952] gives the specification for names that may be used for host names on the Internet. It is updated by RFC 1123 [RFC1123], which relaxes the specification somewhat. It is somewhat unclear wheter the relaxation is per label or per entire host name. In order to avoid problems based on lack of clarity, the specification for a TLD name is hereby stated to be as follows: A TLD label MUST be at least two characters long and MAY be as long as 63 characters - not counting any leading or trailing periods (.). It MUST consist of only ASCII characters from the groups "letters" (A-Z), "digits" (0-9) and "hyphen" (-), and it MUST start with an ASCII "letter", and it MUST NOT end with a "hyphen". Upper and lower case MAY be mixed at random, since DNS lookups are case-insensitive. Hence, the ABNF expression that matches a valid TLD label is as follows: tldlabel = ALPHA *61(ldh) ld ldh = ld / "-" ld = ALPHA / DIGIT ALPHA = %x41-5A / %x61-7A ; A-Z / a-z DIGIT = %x30-39 ; 0-9 This new specification reflects current praxis in registration of TLD names by the IANA, and allows for IDNs. Liman Expires September 5, 2009 [Page 4] Internet-Draft Top Level Domain Name Specification March 2009 3. Other Limitations on Top Level Domain Labels It is carefully noted that the above specification is not the only limiting factor on TLD labels. There may be other entities than the IETF that have influence over TLD names, and which may decide to restrict the names further. The above technical specification is just one limiting factor. Liman Expires September 5, 2009 [Page 5] Internet-Draft Top Level Domain Name Specification March 2009 4. IANA Considerations This memo changes the specifications for TLD names registered by the IANA, and the IANA is requested to change its registration process to use the above specification. Liman Expires September 5, 2009 [Page 6] Internet-Draft Top Level Domain Name Specification March 2009 5. Security Considerations This document does not introduce any new security issues. It may introduce stability issues where names registered under this new specification may interoperate badly with old software written to enforce a strict interpretation of the old specification. However, it is belived that such software is scarce on the Internet, and since TLD names that do not adhere to a strict interpretation of the old specification are already used (including IDNs) without apparent problems, it is believed that this change of the specicification will not create major stability problems on the Internet. Liman Expires September 5, 2009 [Page 7] Internet-Draft Top Level Domain Name Specification March 2009 6. References 6.1. Normative References [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC1123] Braden, R., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, October 1989. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3490] Faltstrom, P., Hoffman, P., and A. Costello, "Internationalizing Domain Names in Applications (IDNA)", RFC 3490, March 2003. 6.2. Informative References [RFC0952] Harrenstien, K., Stahl, M., and E. Feinler, "DoD Internet host table specification", RFC 952, October 1985. Liman Expires September 5, 2009 [Page 8] Internet-Draft Top Level Domain Name Specification March 2009 Author's Address Lars-Johan Liman Autonomica AB Bellmansgatan 30 SE-118 47 Stockholm Sweden Email: liman@autonomica.se URI: http://www.autonomica.se/ Liman Expires September 5, 2009 [Page 9]