What is a potential flaw of MAC address filtering?

• A. It blocks all devices from connecting.
• B. It encrypts only the wired connections.
• C. It may not be sufficient alone for securing a network, as devices with proper credentials can still connect.
• D. It prevents any unauthorized access by default.

Answer: (C)

MAC filtering is not a strong form of network authentication because the identifier it relies on—the device’s MAC address—can be observed, copied, or easily spoofed. If a device has an allowed MAC address, it can connect, and an attacker can masquerade as that device by changing their own NIC’s MAC to match. That means the filter can be bypassed, even when the device appears to have the right “credentials.”

This is why MAC filtering should not be relied on as the sole defense. It’s useful as a light, secondary gate to deter casual access, but it doesn’t provide solid security on its own. For stronger protection, pair it with robust authentication like 802.1X/EAP and strong encryption (WPA2/WPA3), plus other controls such as network segmentation and monitoring.