Introduction to IDN

What is IDN?

IDN (Internationalized Domain Name) denotes a domain name, containing diacritic national signs, characteristic of a particular language, for example, in the Polish language those signs are the following: ą, ć, ę, ł, ń, ó, ś, ż, ź.

Thanks to the facility of registering domain names, for example, with Polish signs, they may be read originally (e.g. są not, kąt not

From a technical point of view, there are two formats of IDN:

  • Unicode format with “tails” - written with Unicode signs, i.e. with diacritic signs characteristic of a particular language (e.g. ż,
  • ASCII format - recoded to ASCII signs, beginning with “xn—“ prefix and containing only signs of the Latin alphabet (e.g. A domain name in that format is stored in DNS resources (in configuration files of DNS servers).

Do you know that IDNs are not limited only to Polish diacritic signs?

Just as well as ż you can register: בית.pl, велосипед.pl, παραλία.pl. Please note that it is not allowed to combine signs of different sets of defined national signs in one domain name registration rules at NASK , e.g. to insert a Polish diacritic sign “tail” and a Hebrew letter. IDN, submitted to registration in ASCII format, must contain signs of only one set.


The subject matter of the agreement with NASK is registration and maintenance of a domain name in ASCII format with "xn--" prefix (e.g., not in a unicode format (np. ż

Domains in ASCII format are registered in accordance with a standard currently in force. NASK shall not be held liable for the results of adapting a worldwide recognized standard other than that applied on the day of registration of a domain name.

Where can I register IDN?

IDN may be registered through registrars, which signed with NASK the agreement on partner cooperation. All questions regarding fees and a registration procedure should be referred directly to the registrars. They are ready to provide you with their offer and assist in registration of a domain name.

IDN/ASCII converter with domain search engine

This tool enables converting a domain name with diacritic national signs (i.e. written in a Unicode format, e.g. ż to ASCII format (e.g. and vice versa.

You may also check the availability of IDN.