ASP.NET forms authentication. How to automatically log out after restarting IIS? How to know that IIS has been restarted?

Question

ASP.NET

Setting from web.config:

<authentication mode="Forms">

    </authentication>

How to know that IIS has been restarted?
While came to mind at the first authorization to write in HttpContext.Current.Application to save something. When restarting, just check if there is no record, then log out everyone. And how to do it, you need to think more. There are some thoughts, but it is necessary to check.