Is it possible to have one (single) character top level domain name?

Question

I\'m writing a Regex to validate email. The only one thing confuse me is:

Is it possible to have single character for top level domain name? (e.g.:

Answer 1

I'm not sure about the internet standard, but in practice, no.

See,

http://www.norid.no/domenenavnbaser/domreg.html

and,

http://sqa.fyicenter.com/Online_Test_Tools/Domain_Name_Format_Validator.php