What is the purpose of switch port security?

• A. To limit the number of MAC addresses learned on a port and prevent spoofing and theft.
• B. To increase the maximum frame size on a port.
• C. To assign VLANs to all ports automatically.
• D. To disable STP on the port.

Answer: (A)

Port security centers on controlling who can send frames through a switch port by limiting the MAC addresses the switch will learn on that port. By setting a maximum number of MAC addresses for a port, the switch only accepts traffic from those known devices. If a device with an unknown MAC tries to send frames, or if too many distinct MACs appear on that port, the switch can take action to block or isolate that traffic. This helps prevent MAC spoofing (impersonating another device by using a different MAC) and MAC flooding (flooding the switch with many different MAC addresses to disrupt learning and traffic).

So, the purpose is to restrict the set of MAC addresses on a port to protect against impersonation and theft. It’s not about frame size, automatic VLAN assignment, or disabling STP, which are unrelated features.