Under which two circumstances is a switch port that is configured with PortFast BPDU guard error-disabled? (Choose two.)
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A. B. C. D. E.Explanation
PortFast is a feature that is used to reduce the amount of time a switch port spends in the blocking state when transitioning from the listening and learning states to the forwarding state. BPDU guard is a feature that is used to protect the network from loops by disabling a port that receives BPDUs. Here are the two circumstances under which a switch port configured with PortFast BPDU guard is error-disabled:
A. When the switch receives a BPDU from a connected switch: In a network with multiple switches, it is possible that a loop may occur if a switch port configured with PortFast receives a BPDU from another switch. The switch detects that a BPDU has been received on the PortFast-enabled port and immediately shuts down the port, putting it in the error-disabled state to prevent a loop from occurring.
D. When a wireless access point running in bridge mode is connected to a switch: A wireless access point running in bridge mode connects the wireless network to the wired network. If a port is configured with PortFast and BPDU guard and a wireless access point running in bridge mode is connected to it, it is possible that the wireless access point will start to send BPDUs, which will be detected by the switch. The switch will then disable the port to prevent a loop from occurring.
B, C, and E are incorrect answers. They do not describe situations that would cause a switch port configured with PortFast BPDU guard to be error-disabled.
B. When the switch receives a request for an IP address from an individual PC: This scenario does not relate to the operation of PortFast BPDU guard. DHCP requests are sent to a DHCP server, which assigns IP addresses to clients. Switches do not participate in this process.
C. When a connected server has more than one VLAN configured on its NIC: This scenario does not relate to the operation of PortFast BPDU guard. A switch port can have multiple VLANs configured on it, and the switch will tag the packets with the appropriate VLAN ID as they are sent to the server. This does not affect the operation of PortFast or BPDU guard.
E. When a single IP address is configured on the switch AC: This scenario does not relate to the operation of PortFast BPDU guard. Configuring an IP address on a switch does not affect the operation of PortFast or BPDU guard.