CompTIA Security+ Question D-6

Which of the following would be MOST appropriate to secure an existing SCADA system by preventing connections from unauthorized networks?

A. Implement a HIDS to protect the SCADA system
B. Implement a Layer 2 switch to access the SCADA system
C. Implement a firewall to protect the SCADA system
D. Implement a NIDS to protect the SCADA system

Answer: C

Firewalls manage traffic using filters, which is just a rule or set of rules. A recommended guideline for firewall rules is, “deny by default; allow by exception”. This means that if a network connection is not specifically allowed, it will be denied.