DNS comes with a set of rules defining valid domain names. A domain name cannot exceed 255 octets (RFC 1034) and each label cannot exceed 63 octets (RFC 1035). It can contain any character (RFC 2181) but extra rules apply for hostnames (A and MX records, data of SOA and NS records): only alphanumeric ASCII characters and hyphens are allowed in labels…
Tag: IDN
Internationalized Domain Name (IDN) and PHP
Currently, PHP doesn’t have any native support of IDN: domains with non-ASCII characters such as http://www.académie-française.fr. If you try to connect to such site you’ll get nothing but an error: file_get_contents(‘http://académie-française.fr’); // PHP Warning: file_get_contents(): php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known in php shell code on line 1 RFC 3490 specifies that applications must convert IDN…