What is the function of the 802.1x protocol in network security?

• A. To assign IP addresses to devices.
• B. To control access to the network by authenticating devices.
• C. To encrypt data over wireless medium.
• D. To monitor bandwidth usage.

Answer: (B)

802.1x is a port‑based Network Access Control mechanism that authenticates devices before they can access the network. In practice, the switch or wireless access point acts as the authenticator, the client is the supplicant, and a central authentication server (often using RADIUS) verifies the credentials via EAP methods. If authentication succeeds, the port is opened and the device is allowed onto the network; if not, access is blocked. This prevents unauthorized devices from connecting and enforces network access policies. It does not assign IP addresses (that’s DHCP), nor does it encrypt data by itself (encryption is provided by the underlying wireless security or EAP method), and it doesn’t monitor bandwidth usage.