Are external config files cached by default?

I have this in my web.config:
<appSettings configSource="configuration\appsettings.config" />
The reason for this is to make the web.config easier to manage, and we do want the updated values to be reflected instantly so we do not use the file attribute and configSource instead.
Now my question is, we know web.config is cached by default and will restart the application when an update is made.  Are these external files also cached by default?  It does not seem so if the changes will be reflected instantly, or does it cache but will automatically detect change and update the cache?
Thanks in advance for any feedback.