How can a company prevent unauthorized devices from connecting to its wired network? Learn why 802.1X authentication is the most effective security feature for controlling LAN access—essential for Cisco Certified Support Technician (CCST) Networking 100-150 exam success.
Table of Contents
Question
A company wants to prevent unauthorized devices from connecting to its wired network. What security feature should be used?
A. VLAN hopping
B. MAC address filtering
C. DHCP snooping
D. 802.1X authentication
E. Port mirroring
Answer
D. 802.1X authentication
Explanation
802.1X enforces authentication before allowing a device to connect to a network, preventing unauthorized access.
The most effective security feature to prevent unauthorized devices from connecting to a company’s wired network is 802.1X authentication.
802.1X authentication is a network access control protocol that enforces user or device authentication before granting access to the network. When enabled on a switch port, 802.1X requires any connecting device to provide valid credentials (such as a certificate or username/password) that are verified by an authentication server, typically a RADIUS server.
If the credentials are valid, the device is allowed onto the network. If not, access is denied, and no network traffic can pass through that port. This ensures that simply plugging in a device is not enough to gain network access, effectively blocking unauthorized devices—even if someone physically connects to a network port.
802.1X is widely recognized as the industry standard for wired network authentication and is recommended for environments where physical access to network ports cannot be tightly controlled.
Other methods, such as MAC address filtering or DHCP snooping, offer some protection but are easier to bypass and do not provide the robust, credential-based access control that 802.1X delivers.
802.1X authentication enforces user or device authentication before allowing network access, providing strong protection against unauthorized device connections on wired networks.
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