What does a router do when it receives a connection request from a device with an unrecognized MAC address?

What does a router do when it receives a connection request from a device with an unrecognized MAC address?

• A. It denies access to the network.
• B. It denies access until a user visits a captive portal.
• C. It assigns a temporary IP and allows.
• D. It automatically retrains the MAC address on the device.

Answer: (A)

MAC filtering is a network access control at the data link layer. A router or wireless access point keeps a list of allowed hardware (MAC) addresses. When a device with a MAC address not on that list tries to connect, the AP denies the association, so the device can’t reach the network or obtain an IP address. That’s why the correct choice is that access is denied. Captive portals apply a login page after connection, which isn’t about blocking based on MAC by default; DHCP would only hand out an IP if the device is allowed to connect, and there’s no standard “retrain MAC” feature.

MAC filtering is a network access control at the data link layer. A router or wireless access point keeps a list of allowed hardware (MAC) addresses. When a device with a MAC address not on that list tries to connect, the AP denies the association, so the device can’t reach the network or obtain an IP address. That’s why the correct choice is that access is denied. Captive portals apply a login page after connection, which isn’t about blocking based on MAC by default; DHCP would only hand out an IP if the device is allowed to connect, and there’s no standard “retrain MAC” feature.