About IDN domains registration

IDN (Internationalized Domain Names) are the domain names which contain national alphabet characters, e.g.:
имя.su
компания.рф

Due to technical limitations the domain names may not contain non-Latin characters. Thus, in order to accommodate this limitation special standards RFC 3490, RFC 3491, RFC 3492 and RFC 3454 have been developed according to which such names are mandatory converted into a set of English letters, numerals and hyphens and a special prefix "xn--" is put in front of such converted name. This conversion is called Punycode. It enables coding the names in national alphabet using ASCII characters.

The conversion process is performed by the client's browser. Thus, two strings "пример.испытание" and "xn--e1afmkfd.xn--80akhbyknj4f" entered into browser have the same meaning for modern browsers (for the browsers of previous versions only the second alternative will work). DNS server databases store only the second alternative. In fact, internationalized domain names are aliases for the names starting with "xn--".

Multilingual SU domain names registration has become available since April 28, 2008. The allowed script tables for SU TLD..

Domain names registration in national РФ TLD has become available since November 25, 2009.