code: def is_fqdn(hostname):
      
  
      compliant = re.compile(r"(?!-)[A-Z\d\-\_]{1,63}(?<!-)$", re.IGNORECASE)
      return "." in hostname and len(hostname) < 0xff and all(compliant.match(x) for x in hostname.rstrip(".").split("."))
docs: Verify if hostname conforms to be a FQDN.
  
      :param hostname: text string with the name of the host
      :return: bool, True if hostname is correct FQDN, False otherwise