# File lib/domain_name/punycode.rb, line 169
    def encode_hostname(hostname)
      hostname.match(/[^\x00-\x7f]/) or return hostname

      hostname.split('.').map { |name|
        if name.match(/[^\x00-\x7f]/)
          'xn--' << encode(name)
        else
          name
        end
      }.join('.')
    end