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SSAC Response to ICANN's Proposed Next Steps for IDN Deployment in the Root Zone

The statement is published on the SSAC website at http://www.icann.org/committees/security/ssac-documents.htm [SAC020].

SSAC Response to IDN Program Director regarding ICANN's proposal for IDN deployment at the root level of the DNS

The Security and Stability Advisory Committee has been invited to comment on ICANN's proposal for IDN deployment at the root level of the DNS. The committee offers the following comments and observations:

  • SSAC concurs with the RSSAC 18 March 2007 public statement [see http://www.icann.org/announcements/announcement-18jun07.htm] that that policies regarding IDNs is out of the committee's scope and takes no position on composition of strings (except that they be unique) and the number of strings per TLD.
  • SSAC further concurs with RSSAC that the root zone should accommodate a factor of 2-5 times the number of TLDs without introducing technical instability.
  • SSAC favors the introduction of a set of IDN labels associated with the .TEST TLD to provide ongoing testing of IDN deployment at the root level of the DNS
    .
  • SSAC is content to leave the duration of the test is left to the discretion of the parties engaged in testing but recommends that an end date be specified.

With regards to technical and operational issues, SSAC has considered the findings from 18 March RSSAC meeting in the Praha and concurs with said findings regarding the addition of standard delegations (NS records) to the root zone to instantiate IDN at the root and the the value of consulting with DNS experts to determine appropriate TTL values for test IDNs. SSAC will also work with RSSAC should either committee be asked to provide input on the matter of aliasing of domain names in the root zone.

SSAC requests the courtesy of continued notices from ICANN during the course of testing, from inception to conclusion, and looks forward to the opportunity to review findings from the tests, including data or measurements provided by the root server operators during the course of the testing.

Stephen Crocker, Chairman
(On behalf of the Security and Stability Advisory Committee)


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Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as""icann.org"" is not an IDN."