Which access control method blocks or allows devices based on MAC addresses?

The correct answer is related to the function of port security, which is specifically designed to restrict access at the switch port level based on the MAC addresses of connected devices. In a network environment, port security can be implemented on switches to allow only devices with a specified MAC address to connect to a network port. This helps prevent unauthorized devices from accessing the network and enhances overall security.

Port security works by monitoring the MAC addresses of devices that attempt to connect and either allowing them based on a pre-configured list or blocking them if they are not recognized. This method is particularly effective in environments where devices need to be tightly controlled, as it ensures that only known and trusted devices can communicate on the network.

Other choices, such as access control lists (ACLs), primarily apply to routing and access policies determining which IP addresses or protocols can pass through a router or firewall, rather than functioning at the MAC address level. Host and network intrusion detection systems are more focused on monitoring traffic and detecting anomalies or malicious activity rather than controlling access based on MAC addresses.