Turning VS off when nodes down

I kind of don't understand what you are asking? I want to basically disable a Vip address / Virtual server if all my nodes are down. In the case where the Virtual server supports more than one url I would think if the pmultiple pools are involved the traffic would pass and the application with the issue would have an issue. In the case where one pool is responsible for multiple urls if the nodes equal 0 then the url's will all be down.