I am trying to learn nmap. I am running several host discovery commands. With the -PR, -PU, -PE, -PP, -PM, -PS, -PA. All with the -sn flag. I have Wireshark open and I see that every single command sends an ARP request and gets a ARP reply. All of the packets from each command are exactly the same down to the last bit. If this is the case what is the difference between each of those different flags ?