Where is MAC address learning enabled by default?

MAC address learning is a fundamental function of Ethernet switches, enabling them to build a MAC address table (CAM table) by inspecting the source MAC addresses of incoming frames. This process is essential for efficient frame forwarding, as it allows the switch to send frames only out of the specific port connected to the destination device, rather than flooding all ports. Because it's integral to basic switch operation, MAC address learning is enabled by default on all VLANs and all interfaces on a Cisco switch. The other options describe specific security features (like port security or unknown unicast flooding behavior) that are not the default state of MAC address learning itself.