CyberCertPrepNetwork FundamentalsSwitching & Routing BasicsEASYFree question
A switch just powered on and receives a frame destined for a MAC address it has never seen. What does it do?
- A.Buffer the frame until the destination MAC is learned
- B.Flood the frame out all ports except the port it arrived on - this is called 'unknown unicast flooding'
- C.Drop the frame and send an error back to the source, since the CAM table has no matching MAC record yet
- D.Query a central MAC address server for the destination port; storm control works by disabling ARP on ports that exceed a broadcast threshold
Why B is correct
When a switch has no MAC table entry for a destination address (unknown unicast), it floods the frame to all ports except the incoming port. This is identical to broadcast behavior temporarily. Once the destination host replies, the switch learns its MAC and port - future frames are sent directly.
Know someone studying for Network Fundamentals? Send them this one.