I don't know what's the relationship between application status and component status.
Does any one can explain that? Thank you!
an application contains several components, for example you might have application1 with one service that needs to run and a check that its website is up. if the service is still running but the website is unreachable, the component for the website goes down.
for normal roll-up this means that the application itself will gain the worst status of any component it contains, therefore the application would go down even though the service is still running as the website monitor declared the application to be down.