Given the simple well-known architecture below:
Where (conceptually) does the caching server(s) sit?
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Your caching layer sits between Model and View Controller. You should not hit database for needless requests. These requests include in my opinion.
Note that Caching does not need to be for database only. For example you may cache messages from mail server, or expensive file parsing operation result also.
Caching is the number one layer which increases speed of application.