MAC access control lists (ACLs) are used to permit or deny devices by their MAC addresses.

• A. True
• B. False
• C. Not specified
• D. Both

Answer: (A)

MAC ACLs filter frames by the Ethernet header's MAC addresses, making them a layer-2 mechanism to permit or deny traffic from specific devices based on their hardware addresses. This means you can allow traffic from a known MAC on an interface while blocking others, without relying on IP addresses. They’re useful in switches or devices that support MAC-based filtering to enforce access at the point where frames are forwarded, before IP processing occurs. In practice, this approach complements other controls like 802.1X or IP-based ACLs, and while effective for certain threats, it isn’t highly scalable and can be bypassed by MAC spoofing, so it’s usually part of a layered security strategy. The statement is true because MAC ACLs are specifically designed to permit or deny traffic using MAC addresses.