how does the MAC address change when a frame passes a switch?

Question

there is a scenario. host A is connected to a switch S, and switch B is connected to a host C. just like this: A----switch---B. A sends a message to host C through switch S. switch S delivers this message to B. when B receives this message, is the source MAC address A's? does switch S attach its own MAC address to this message without changing the source and destination MAC address?

Answer 1

A plain vanilla switch doesn't have a MAC address. Only the originating and destination hosts' MAC addresses should be in the packet.