How archiving task knows where to resume archiving?

Hi Experts,

I've got two questions to which I've not found any answer till now.

How the Exchange Mailbox Archiving Task knows where to resume with the scheduled archiving the next time?

Example: I've one Exchange mailbox server with four databases; let's say database 1-4 and the archiving task is scheduled from 5pm till 5am in the morning. During the day no archiving task are running. During the archiving period maybe only database 1-2 getting archived. So how the archiving task knows the next time where to continue so that the task is not starting again with database 1 and continue on database 3?

Thanks to all!

EV 9.0.1.1073