Which device is primarily used to enforce access control by filtering traffic at a network boundary?

Which device is primarily used to enforce access control by filtering traffic at a network boundary?

• A. Firewall
• B. Router
• C. Switch
• D. Load balancer

Answer: (A)

Filtering traffic at a network boundary to enforce access control is the firewall's primary role. Firewalls sit at the edge between trusted and untrusted networks and enforce security policies by permitting or blocking traffic based on rules that consider source and destination IPs, ports, protocols, and often deeper inspection of the traffic. They also often maintain state for connections, which helps ensure only legitimate return traffic is allowed and reduces the chance of certain attacks slipping through. Routers focus on directing traffic between networks and may support basic access lists, but their main purpose isn’t enforcing security at the edge. Switches operate inside a LAN to forward frames and may apply simple ACLs, yet they’re not designed for comprehensive boundary enforcement. Load balancers distribute client requests across servers to improve performance and availability, not to enforce access control at the network boundary.

Filtering traffic at a network boundary to enforce access control is the firewall's primary role. Firewalls sit at the edge between trusted and untrusted networks and enforce security policies by permitting or blocking traffic based on rules that consider source and destination IPs, ports, protocols, and often deeper inspection of the traffic. They also often maintain state for connections, which helps ensure only legitimate return traffic is allowed and reduces the chance of certain attacks slipping through. Routers focus on directing traffic between networks and may support basic access lists, but their main purpose isn’t enforcing security at the edge. Switches operate inside a LAN to forward frames and may apply simple ACLs, yet they’re not designed for comprehensive boundary enforcement. Load balancers distribute client requests across servers to improve performance and availability, not to enforce access control at the network boundary.