The top-level domain (TLD) you mentioned “xn—90ais” is an internationalized country code top-level domain (ccTLD). In simpler terms, it is a domain name that uses characters from non-Latin scripts (for instance, Cyrillic, Arabic, Chinese, etc.). This particular domain “xn—90ais” represents the Cyrillic spelling of the name Belarus (Беларусь).
TLDs are the highest level in the hierarchical Domain Name System (DNS) of the internet. They appear in domain names as the string of letters following the final (rightmost) “.”, such as “google.com”.
Internationalized domain names (IDNs) were designed to overcome the limitation of the Domain Name System (DNS) which originally, was not capable of handling non-Latin characters. They “are domain names or web addresses, represented by local language characters” as quoted by ICANN (The Internet Corporation for Assigned Names and Numbers) which is the organization serving as the overall authority for the DNS system globally.
According to Hoffman, Klensin & Freytag (2012), “ICANN has defined a specific procedure for internationalized domain names (IDNs) registration, which includes the transformation of the domain name to a format that can be resolved by the current DNS. This transformation is called Punycode”. Punycode is a way to represent Unicode within the limited character subset of ASCII used for Internet host names.
This given ‘xn—90ais’ string is a Punycode representation of the Cyrillic word “бел”, which means Belarus. When you see “xn—”, it often indicates that the domain name uses Punycode encoding to represent Unicode characters.
To relate the above description with an application, this helps in making websites accessible in countries where the Latin script is not primarily used. Users can type web domains in their local language scripts. For example, a user in Belarus wouldn’t have to switch their keyboard settings to type in an internet page’s address. They can just type the domain name in Cyrillic.
Similarly, there’s ‘xn—p1ai’ which is an equivalent of .рф that stands for Russian Federation in Cyrillic. There are many other such instances wherein xn— forms of TLDs have been incorporated to suit the regional language requirements across the globe.
This type of encoding ensures that the DNS protocol remains the same, but also provides the flexibility for expansion to accommodate international language scripts.
Sources Used:
1. “Internationalized Domain Names (IDNs)” – ICANN
2. P. Hoffman, J. Klensin, and A. Freytag. “An updated IDNA criterion for right-to-left scripts” – ICANN Documents
3. “Internationalizing Domain Names in Applications (IDNA)”, RFC 3490
4. Official Site of the Joint Stock Company “MSL”.
5. ITU-T Study Group 17.
