I am having issues with installing ASP.NET 4.0 on other servers. Everytime I install it, it seems that IIS has different app pools setup for 4.0. They are never the same. Sometimes I get ASP.NET 4.0 + ASP.NET 4.0 Classic + ASP.NET 4.0 DefaultAppPool. Other times I get more than that. Sometimes they are all set to classic. Other times just one is set to integrated. What the hell is going on here?! What controls this setup? This is making installation of my new Silverlight app frustrating for our customers because the instructions are inconsistent.
I think I understand what you are asking. The installation of .NET 4.0 does not create or edit any application pools that I am aware of. Are you manually creating the app pool for your application? The only app pool that matters is the one that your application is using. The different app pools you are seeing were likely created for other applications and likely won't have any bearing on your application. So you could use the default app pool, but likely the path of least resistance is to create a new app pool for your application since it will likely confuse the end-user to sift through previously created application pools that were probably intended for somebody elses application.