XSS - Warning popup in

Hi,

I am new to XSS world and trying to understand the IE popup on XSS alert.

Using IE 11, sometimes i am getting an alert for the below URL and now i am not getting.

I have not changed any IE settings - which means the XSS script filter in in enabled state only

e.g. :  localhost:8080/xss1.jsp?name=guest<script>alert('attacked')</script>

So, why there is no consistency in XSS alert popup?

-JainCJ