How long can a TLD possibly be?

Question

I\'m working on an email validation regex in PHP and I need to know how long the TLD could possibly be and still be valid. I did a few searches but couldn\'t find much infor

Answer 1

The longest with latin letters is .MUSEUM (source), but there are some with special characters. The longest from them is XN--CLCHC0EA0B2G2A9GCD. Also, in a short time, it will be possible to reserve your own TLD for a high price and so it will be possible to be longer.