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Mitigating the Risk of DNS Namespace Collisions Final Report by JAS Global Advisors

ICANN today announced the publication of "Mitigating the Risk of DNS Namespace Collisions Final Report," a report by JAS Global Advisors ("JAS"). This is the complete version of the report previously published in June 2014 at [PDF, 392 KB].

The phase one report was used by ICANN as a base to develop the Name Collision Occurrence Management Framework that has been in use by new gTLDs for more than a year. The final JAS report is being published to provide full background to what later became the Framework. The final JAS report does not contain any new or amended recommendations, and registry operators will continue to be required to implement the name collision mitigation measures identified in the existing Framework.

At the time of publication of the phase one report, JAS uncovered a vulnerability not directly related to ICANN's New gTLD Program nor to new TLDs in general that had the potential to impact end-systems. Following its Coordinated Vulnerability Disclosure Reporting process [PDF, 628 KB], ICANN agreed to the requests from JAS and the affected vendor to postpone publishing the full report until the risks raised by the vulnerability had been mitigated.

 The affected vendor has since addressed the risks raised by the vulnerability, and , ICANN is now publishing the full report at [PDF, 10.9 MB] and a redline from the phase one report at [PDF, 970 KB] (without considering the appendices).


ICANN's mission is to ensure a stable, secure and unified global Internet. To reach another person on the Internet you have to type an address into your computer - a name or a number. That address has to be unique so computers know where to find each other. ICANN coordinates these unique identifiers across the world. Without that coordination we wouldn't have one global Internet. ICANN was formed in 1998. It is a not-for-profit public-benefit corporation with participants from all over the world dedicated to keeping the Internet secure, stable and interoperable. It promotes competition and develops policy on the Internet's unique identifiers. ICANN doesn't control content on the Internet. It cannot stop spam and it doesn't deal with access to the Internet. But through its coordination role of the Internet's naming system, it does have an important impact on the expansion and evolution of the Internet. For more information please visit:

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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."