code: public URLNormalizer replaceIPWithDomainName() {
          URL u = toURL();
          if (!PATTERN_DOMAIN.matcher(u.getHost()).matches()) {
              try {
                  InetAddress addr = InetAddress.getByName(u.getHost());
                  String host = addr.getHostName();
                  if (!u.getHost().equalsIgnoreCase(host)) {
                      url = url.replaceFirst(u.getHost(), host);
                  }
              } catch (UnknownHostException e) {
                  logger.debug("Cannot resolve IP to host for :" + u.getHost(), e);
              }
          }
          return this;
      }
docs: <p>Replaces IP address with domain name.  This is often not
  reliable due to virtual domain names and can be slow, as it has
  to access the network.</p>
  <code>http://208.77.188.166/ &rarr; http://www.example.com/</code>
  @return this instance