Understanding IDN Domains.
An internationalized domain name (IDN), a domain name that contains at least one letter in a language-specific alphabet other than English, such as Arabic, Russian, Tamil, Chinese or the Latin characters with accents, such as French. These are stored in the Domain Name System as ascii strings using the Punycode code encoding system.
Thus the domain fênêtre.com becomes xn--fentre-kva.com in the punnycode translation.
All IDN domains will be encoded into an ascii string starting xn-- and when displayed in a browser will display in their native language alphabet.