Well, as the board so elegantly puts it, I am a newbie.
So there seems to be many reasons for a device to send an RST, with no clear answer, from firewalls to response to receiving a packet.
But this, if I understand correctly, is being send and resend after the retransmission, from one private host to another.
For the sake of helping with the homework.. what could be achieved by doing this on, say, purpose?