// for use in applets when you can't set the ttl properly
 public static void clearDNSCache() {

    try {
      Field field = InetAddress.class.getDeclaredField("addressCache");
      field.setAccessible(true);
      Object obj = field.get(null);

      // synchronized on addressCache
      synchronized (obj) {
        Field cacheField = obj.getClass().getDeclaredField("cache");
        cacheField.setAccessible(true);
        Map cacheMap = (Map) cacheField.get(obj);
        cacheMap.clear();
      }
      System.err.println("Cleared DNS cache.");

    } catch (Exception e) {
      e.printStackTrace();
    }
  }