A station with MAC address A connected to port 1 on an Ethernet swich only sends frames with source MAC address B, and the station with MAC address B connected to port 2 only sends frames with source MAC address A. What entries for A and B will be in the switch's table? If another station on the switch sends a frame F with destination MAC address A, what will happen to this frame?

The teacher provided the answer, but I don't understand it:

Entries:

B Port 1

A Port 2

F will be sent on port 2 and B's card will get it. If B's card works in the usual way, it will discard it.

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I'm confused as to what this looks like drawn. I don't understand why if MAC address A is connected to port 1, it's sending out a source with MAC address B. Can network cards pretend to have a different address?