Init Packet

I'm referring this

which states that when in bootloader mode, I've to send the init packet first & then the firmware image.

So what happens after I send 06 01 command. What is init packet? How do I create one? The response received for each command - is it written over a characteristic or a descriptor inside characteristic? My understanding is DFU Control Point & DFU Packet characteristics do not support read property. So where can I see the response received for every command sent by host to BLE device?

Sorry I could not understand a thing from the sniffer trace which I captured while executing the actual DFU procedure listed on Nordic Infocenter. I'm using SDK 15.2 & nrf52832.