Explain how a firewall differs from an access control list (ACL) in traffic control.

• A. A firewall filters traffic based on rules and can be stateful; an ACL is a list of permit/deny rules applied at a device interface to block or allow traffic.
• B. A firewall only monitors traffic; an ACL blocks traffic.
• C. An ACL provides full stateful inspection across all traffic.
• D. A firewall and an ACL perform identical functions in all scenarios.

Answer: (D)

The main idea is that a firewall provides stateful, context-aware filtering with broader security features, while an access control list is a simpler, stateless set of permit/deny rules applied to an interface. A firewall keeps track of active connections, can inspect traffic across different layers, and can enforce policies based on session state, application type, and even user identity. It often includes features like NAT, VPN termination, intrusion prevention, and detailed logging. An ACL, by contrast, is basically a list of rules that decide whether to allow or block packets as they arrive at a device interface, and it typically evaluates each packet in isolation without understanding the larger connection or the payload beyond basic fields like IP addresses, ports, and protocol. Because of that, firewalls offer more nuanced and extensive control, whereas ACLs provide simpler, more limited traffic filtering at the device boundary. In scenarios requiring deeper inspection and broader policy enforcement, the firewall handles the job, and an ACL alone would not suffice.