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Release of Interisle and TNO reports on Root Scaling

In February 2009, with Resolution 2009-02-03-04, the ICANN Board requested the Root Server System Advisory Committee (RSSAC), the Security and Stability Advisory Committee (SSAC), and the ICANN staff, including the IANA team, to study the potential issues regarding the addition of IDNs, IPv6 addresses, DNSSEC and substantial numbers of new TLDs to the root zone. The Terms of Reference for this study are at

Interisle was selected to perform this study. In the course of their study, they recommended that a modeling effort be undertaken with the assistance of TNO. TNO produced a model and a companion report.

We are hereby releasing the Interisle report as delivered for public comment and analysis as well as a covering note from the joint RSSAC/SSAC/ICANN staff steering group for this study.

The steering group will be evaluating the report against the Terms of Reference and preparing recommendations for the Board and the public.

The TNO model and simulation system with the TNO report can be found at:

Related links:

Root Scaling Study [PDF, 1,340K]

Steering Group transmittal letter [PDF, 41K]

The Root Scaling Study Steering Group

David Conrad ( - ICANN
John L. Crain ( - ICANN
Steve Crocker ( - SSAC
Jeremy Hitchcock ( - SSAC
Johan Ihrén ( - RSSAC
Matt Larson ( - RSSAC
Danny McPherson ( - SSAC
Ram Mohan ( - SSAC
Greg Rattray ( - ICANN
Barbara Roseman ( - ICANN
Suzanne Woolf ( - RSSAC

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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"""" is not an IDN."