> If this limit is a new and independent from the underlying "native" DNS, > what is the reason for it? If it is not independent, why duplicate it?
It isn't independent since the limit derives from the label length limit in the DNS protocol, but the limit is also a function of the amount of compression that punycode performs. The fact that punycode will never generate a string with less number of code points than the number of code points in the input is far from obvious, hence it makes sense in my mind to state this limit. Erik
