Computing Homework

What type of backup(s) would a Large Airline use?(out of Full, Incremental, Differential, Mirroring and Shadowing)
I don't even know what kind of information they would store...

I would presume Mirroring would be used...

A large airline would be storing staff records, bookings (customer info) and much more data.

I thought that Incremental and Differential were the same?

Anyway that would be time efficient and they may not that however thats not really secure, I would imagine they would use Mirroring and then store the copied data to an external area (or a fireproof room).

Incremental is when one full back up is made, then when you back up, it backs up the changes since the full backup. Where as with Differential, it just backs up the changes since the last backup.

Thanks