I know how switch learns MAC addresses after startup, but what I'm not sure about is, when the switch floods a frame (when it doesn't know the destination) does the source port (that sent the frame) also receive the frame?

2 Answers 2


No. Broadcasts are flooded out all interfaces except the one which they were received on. If they were sent on that interface too then you'd have a never ending flow of broadcast traffic.


@OzNetNerd answer is correct however the term you choose could cause some confusion.

  • When a host attached to a switch send a broadcast frame, the switch replicate it to all ports, except the port on which the frame was received.

  • When the switch receive an unicast frame destined to an unknown mac address, the switch will flood it to all ports, except the port on which the frame was received. The frame is still a unicast tough, and not a broadcast.

  • Ah, I suggested an edit to change broadcast to flood in the question before I read this answer. Sorry if that results in this answer making less sense if the edit is approved. Commented May 13, 2016 at 17:49
  • Great answer @JFL. Hopefully the OP will see it too.
    – OzNetNerd
    Commented May 16, 2016 at 3:11

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