What action takes place when a frame entering a switch has a unicast destination MAC address that is not in the MAC address table?

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What action takes place when a frame entering a switch has a unicast destination MAC address that is not in the MAC address table?

  • The switch resets the refresh timer on all MAC address table entries.
  • The switch updates the refresh timer for the entry.
  • The switch replaces the old entry and uses the more current port.
  • The switch will forward the frame out all ports except the incoming port.
    Answers Explanation & Hints:

    When a frame entering a switch has a unicast destination MAC address that is not in the MAC address table, the switch will flood the frame out all ports except the incoming port.

    This is because the switch does not have a destination MAC address entry in its MAC address table to forward the frame to, so it must assume that the destination is on a different network segment and flood the frame out all ports (except the incoming port) in order to reach the destination.

    This flooding behavior is known as unknown unicast flooding, and it can lead to unnecessary network traffic and bandwidth consumption. To mitigate this behavior, switches can be configured with features such as port security, which limits the number of MAC addresses that can be learned on a given port, or dynamic ARP inspection, which validates ARP packets to ensure that they are legitimate before allowing them to update the MAC address table.

For More Questions and Answers Click the link below:

CCNA 2 SRWE – Switching, Routing, and Wireless Essentials (Version 7.00) – SRWE Final Exam Answers Full 100% v7 & v7.02 2023

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