What does it mean when a DNS name starts with xn--?

I found the following domain in my logs:

I have never seen anything like it. Is this a valid domain? If so what is the TLD?

1 Answer

Apparently it's an ascii representation of: .рф

"The domain name рф (romanized as rf [3]) is the Cyrillic country code top-level domain for the Russian Federation, in the Domain Name System of the Internet. In the Domain Name System it has the ASCII DNS name xn--p1ai. The domain accepts only Cyrillic subdomain applications, and is the first Cyrillic implementation of the Internationalizing Domain Names in Applications (IDNA) system."

Reference: