ASP.NET Application Understanding

I am trying to learn the details of ASP.NET Application and bit confused about my understanding on some topics; please clarify if you think I am wrong somewhere.

1. An Application domain is created when a first request is received at the web server.

2. 开发者_StackOverflow中文版

   Multiple Application Domains are created for simultaneous request when existing Application domains are found busy.

3. An Application domain remains alive and reused for further request. This Application domain can shutdown due to server restart or any Modification/Update in Web application files

4. An Application pool can hold anywhere from 1 to 100 Application domains.