What is the default port-security behavior on a trunk link?

It places the port in the err-disabled state if it learns more than one MAC address.. When port security is enabled and default values are left in place, the default maximum number of secure MAC addresses is one and the default violation action is shutdown. On a trunk, learning more than the allowed number of MAC addresses violates the configured port-security policy and places the interface into the err-disabled state. It does not create a network loop, and it does not disable the native VLAN as a default behavior. Cisco CCNA 200-301 v1.1 Network Access includes port security because it is a common access-layer control used to limit which MAC addresses can use a switch port. The corrected answer is that the port is placed in err-disabled state if it learns more than one MAC address. That describes the default violation behavior accurately.