@Ocramius I could check for the availability of idn_to_ascii(). If it wasn't there, it would mean including code similar what [Net_IDNA2](http://pear.php.net/package/Net_IDNA2/) has to decode the UTF-8 U-label to the punycode A-label. It would be functional opposite of [decodePunycode()](https://github.com/zendframework/zf2/blob/master/library/Zend/Validator/Hostname.php#L675). Considering I'm not that level of programmer, it would probably be wholesale inclusion of the Net_IDNA2 logic. 

Is it standard ZF practice to account for missing default extensions? There's been a discussion about the necessity of the pure-php Zend\Json encode/decode logic. I would think this is a similar discussion. Perhaps for 2.4 or 3?