There are many ping utilities that will monitor a working address for becoming not working. I don't know of any that will monitor a not working address for becoming working. The former is useful for people with web sites that want to know when their site(s) encounters a problem. The latter is useful for users of web sites that are not functional so they know when the site becomes functional.
I tried to ensure that I was logged in before creating this, but I was not. I am the creator of this.