[Jane1]

Sorry for this newbie question.
Can anyone please explain when it is better/necessary to use Preloader mode and when BootRom mode. What are advantages of each?
Thank you for explanation.

[maxpayne]

Sorry for this newbie question.
Can anyone please explain when it is better/necessary to use Preloader mode and when BootRom mode. What are advantages of each?
Thank you for explanation.

Preloader mode is the regular flashing mode on MTK while Bootroom is a deeper level like in secure boot devices

[Jane1]

Thanks for the reply. But is it necessary to use DA( download agent) in both modes? And when is it necessary to use Authorization file?

[maxpayne]

Thanks for the reply. But is it necessary to use DA( download agent) in both modes? And when is it necessary to use Authorization file?

Yes, it is. The thing is, for secure boot devices, you need a signed DA (signed to work on a specific device or set of devices). When you go ahead to format the phone (which has secure boot), the DA is no longer enough to verify, this is where the auth file comes in.
Some models however require auth file, format or not