i am trying to serve html file if my coldfusion server is down using IIS, but everytime i ended server not found, i want that a default html page called as index.htm should be executed if cfserver is not running at least IIS should serve html file

Right. So... like... what is the question in all this? Bear in mind that my follow-up is going to be the usual "what have you tried? What did that do instead of what you wanted? Why do you think that might be? What research have you done?" and I will also post a link to http://www.catb.org/~esr/faqs/smart-questions.html. Again. On the off chance you actually read it and take it on board this time.

If your server is behind a load balancer, that is often a great way / location to serve a “server down” message. Since IIS is configured to hand any CFM request off to the cfml engine, that will kick in first. Unless you have a way of doing conditional “send to cfml” engine logic, a load balancer is your best bet.