Will changing applicationHost.config cause IIS7 restart?

Question

If I make a change to the file:

%windir%\system32\inetsrv\config\applicationHost.config

and update it with a change resulting in a valid config, will it cause IIS7 to restart and force restarts on all the apps?

I am trying this out with a hot-cloned vm of the server, but like to know if anyone has experience of either of these scenarios, what the expected outcome should be.

Many thanks

Answer 1

I put together a short video on this just last week. It covers the differences between AppDomains and AppPools and what causes recycles. I walk through various setting changes that cause full recycles and AppDomain recycles. I also cover how you can tell if a recycle occurs and what the impact is.

The short answer is that it depends. 'Touching' applicationHost.config by itself won't cause any level of recycle, but certain config changes will. Any change to .NET's machine.config or root web.config will cause an AppDomain recycle on the server for that framework version. Any change to a site's web.config will cause an AppDomain recycle for that site.

Answer 2

If you edit App Pool properties, the App Pools should recycle (by default, unless disallowrotationonconfigchange is set, or its modern-day equivalent).

Otherwise, no, any system.webServer changes I can think of will not cause a restart of the app pools.

However, modifying web.config values may cause the apps to restart (the AppDomains) if you're using .Net.

See also: http://forums.asp.net/p/1344814/2742551.aspx