I'm reading the chapter for DHCP Snooping/DAI in the OCG for the CCNA and I have a question regarding how gratuitous ARP message attacks work.
I'm sure there is a piece I am missing, but I've searched and haven't been able to find the answer to my question.
Refer to the diagram below: PC-A sends a gratuitous ARP to R2 to update R2's ARP table such that R2 believes 172.16.2.101 has a L2 address of MAC A.
In the steps listed in the diagram, the first is that PC 1 sends traffic to a server through R2. My question is, wouldn't R2 see in the ethernet header that the source MAC from source IP 172.16.2.101 was MAC 1 and not MAC A as it should be according to its ARP table? In other words, if R2 knows that the address 172.16.2.101 is connected to MAC A, and it receives a packet that has MAC 1 as the source and 172.16.2.101 as the source IP, wouldn't it know something is up? I'm probably missing something super simple. Anyways, this is my first question and I hope to get some responses. Thank you...