If that's the desired behavior then cache layer should allow one to use stale (invalidated ) content. Cache layer (or application layers above it) should be awa

If that's the desired behavior then cache layer should allow one to use stale (invalidated ) content. Cache layer (or application layers above it) should be aware of the status of cached data. It's fine if stale data is used deliberately, problems arise when stale data is assumed to be 'fresh'.