Port Security Violation Modes

A

The correct answer is D. restrict.

Port security is a feature of Cisco switches that allows you to control the traffic that is allowed to enter a port based on the MAC address of the device connected to it. Port security can be configured in three different violation modes:

1. Protect mode: In this mode, when the maximum number of allowed MAC addresses is reached on a port, any additional MAC addresses are dropped, but the port remains operational. This mode is used when you want to monitor the traffic on the port without interrupting it.

2. Shutdown mode: In this mode, when the maximum number of allowed MAC addresses is reached on a port, the port is put into an error-disabled state, effectively shutting it down. This mode is used when you want to prevent unauthorized devices from connecting to the network.

3. Restrict mode: In this mode, when the maximum number of allowed MAC addresses is reached on a port, any additional MAC addresses are dropped, but traffic from the authorized MAC addresses is still allowed to pass. This mode is used when you want to allow traffic from authorized devices while preventing unauthorized devices from connecting to the network.

In summary, restrict mode is the mode that allows traffic from valid MAC addresses to pass but blocks traffic from invalid MAC addresses.