What is the difference between web.config timeout and IIS timeout?

Question

What is the difference between the following entry in web.config:

 <sessionState timeout="30"/>

And this setting in IIS 7.5 (Default web site > Advanced Settings > Connection Limits) :

I know that the web.config is supposed to apply to the time that the ASP.NET session is kept alive, but what is the IIS setting for?

Solution

The connection timeout is how long a connection from a browser to the server should take till it times out. So, when the browser requests a page/image/resource, how long should IIS wait till it terminates the connection. It is stated in seconds.

It can also be set in the web.config (example is for 2 minutes, 120 seconds):

<limits connectionTimeout="00:02:00" />

The session timeout is how long the session can live. This is across multiple connections and is stated in minutes.

They are two different settings that control different things.

Comments

[333Mhz]

OK, so they are unrelated, that's really what I wanted to know, thanks.

[Unbreakable]

so, where to put above line of code in config file. Web.config file is a big file where shall I add this piece of code and under which tag?

[Oded]

@Unbreakable - iis.net/configreference/system.applicationhost/sites/site/…

[Palec]

If I'm not mistaken, usually, this limits element can be used only in applicationHost.config, directly in the sites's definition. Overrides are forbidden by default. <section name="sites" allowDefinition="AppHostOnly" overrideModeDefault="Deny" />