If an application consists of 5 components, do all 5 have to be down for the application to be down, or would any component being down trigger the application to be down?
From a monitoring perspective the distinction between applications and components are sometimes lost on the server owners receiving the alerts. I'd like to keep it simple. So if a component is down that effectively renders the application down, one application down alert is preferable. If multiple components are down, I'd rather have one application down alert listing the components with trouble rather than several component alerts.