The rules are 67 characters including the extension such as ".com",
so actually the name has a limit of 63 characters
(in fact, the domain name checker will only allow you to use 63
* characters).
Please note that only 0-9, a-z, and the dash "-" are valid characters.

You may lookup your domain names here
http://internetplanners.com/cgi-bin/whois/cart.pl