Under what circumstance will a switch flood a frame to all ports on the switch?

When the destination MAC address is not in the MAC address table, the switch will flood the frame to all ports on the switch. When the computer or device responds, the switch will record the source MAC address with the port on which it sees the traffic. When the source MAC address is unknown by the switch, it is recorded in the MAC address table as previously described. When a multicast address is seen by the switch, it is selectively switched to specific ports. A MAC address is never set to 0000.0000.0000, as it is an invalid format for a MAC address.