In my website's application pool, the identity is set to "ApplicationPoolIdentity". Normally I would use "Network Service" and give read/modify rights to "Network Service" on the website file system. However, someone told me to use "ApplicationPoolIdentity" instead because the site will have their self contained permissions (so one site cannot update files of another when all under "Network Service").
What NTFS user should I use for providing read/modify permissions to a website's "ApplicationPoolIdentity" though?
Note that this might not be GUI-selectable or GUI-resolvable in the Object Picker with Windows 2008 (as opposed to R2), but should work from a command line, for eg, with ICACLS or similar.