By default, how does port security behave on a trunk port?

By default, when port security is enabled on a trunk port, it is configured with a maximum of one MAC address. If the port learns a second MAC address, it triggers a security violation. The default violation mode is shutdown, which places the port in the err-disabled state, effectively shutting it down to prevent unauthorized access and alert administrators. Incorrect options: "It causes a network loop when a violation occurs" is incorrect because port security's primary function is to prevent unauthorized access, not to cause network loops. Loops are typically caused by spanning-tree misconfigurations. "It disables the native VLAN configuration as soon as port security is enabled" is incorrect. Port security operates independently of native VLAN configurations; it does not alter them. "It places the port in the err-disabled state after 10 MAC addresses are statically configured" is incorrect. The default maximum for port security is one MAC address, not ten, and this applies to learned addresses, not just statically configured ones.