What's the difference between "aspnet_regiis -ir" and "aspnet_regiis -iru"?

Question

The help text of aspnet_regiis utility says the following for "-ir" option:

Install this version of ASP.NET, register only. Do not change any web applications to use this version.

And the following for "-iru" option:

Install this version of ASP.NET. If there are any existing applications that uses ASP.NET, it will not change IIS configuration to use this version.

It must be my English, but I do not understand what the difference is - both won't change any apps to use this version. And I'm afraid that trying this out myself won't be precise, since I hardly know where to look into...

Does anyone know the difference?

Answer 1

ASP.NET IIS Registration Options Summary

-i

Install ASP.NET and updates existing applications to use the specified version of the application pool.

-ir

Installs and registers ASP.NET. This option is the same as the -i option except that it does not change the CLR version associated with any existing application pools.

-iru 

If ASP.NET is not currently registered with IIS, performs the tasks of -i. If a previous version of ASP.NET is already registered with IIS, performs the tasks of -ir.

Essentially, depending on your previous setup, -iru may or may not update existing application pools to the version of ASP.NET you are installing.

Hope this clears things up.

Answer 2

How I understand the parameters of aspnet_regiis.exe the switch -iru should be typically used instead of -ir. The installation of .NET Framework and registration of the Framework in IIS needs some steps like script mapping: association of different .NET special extensions in IIS (see this place for example). The installation can run without the step (switch -ir), but it has more sense to skip the steps only if a previous version of ASP.NET is already registered with IIS. Exactly this do aspnet_regiis.exe -iru. If no previous version of ASP.NET is registered with IIS, then aspnet_regiis.exe -iru do make all registrations in IIS and work like aspnet_regiis.exe -i. If do a previous version of ASP.NET is already registered in IS the aspnet_regiis.exe -iru work like aspnet_regiis.exe -ir.

Answer 3

According to MSDN:

The usage of the -u parameter "uninstalls the version of ASP.NET that is associated with the ASP.NET IIS Registration tool from the computer. Existing script maps to this version of the ASP.NET ISAPI are automatically remapped to the most recent remaining ASP.NET ISAPI version installed."