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ICANN Releases Beta TLD Verification Tool

Today ICANN released a beta version Top-Level Domain (TLD) Verification Tool. This verification tool has been developed in response to problems reported by gTLD registries and end-users of the non-acceptance of some existing TLDs. These problems occur in some current applications because: 1) they do not recognize any TLD of more than three characters; or, 2) they rely on legacy information where only com/net/org and a handful of ccTLDs are recognized as valid.

Applications relying on such erroneous TLD criteria result in an inconsistent experience for users, detracting from the benefits of a single, global interoperable DNS. This TLD verification tool will provide a means for application developers and providers to incorporate current root-zone data into their applications, thereby fostering broad acceptance of all TLDs.

The verification tool is available for download at the following links and is released under an Open Source license:

- Universal Acceptance Toolkit (Beta 2, .tar.gz)
- Universal Acceptance Toolkit (Beta 2, .zip)

This code has been designed to either query top-level domain name validity using the DNS protocol, or to verify top-level domains against an official list maintained by IANA. The tool is being released as a library of functions available in Java, Perl and Python. Sample code has also been developed in C. Additional alternatives may be developed based upon demand.

ICANN will promote the availability of the verification tool via an education campaign directed to Internet Service Providers, website designers, software application developers and other members of the Internet community that are affected by this issue.

ICANN encourages testing and feedback on this beta version of the verification tool. Comments or questions about the tool may be submitted to

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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."