What is the primary purpose of a firewall in a computer network?

• A. To block all inbound and outbound traffic by default.
• B. To monitor network performance.
• C. To monitor and control incoming and outgoing network traffic based on security rules.
• D. To provide encryption for all data.

Answer: (D)

The firewall’s main job is to monitor and control incoming and outgoing network traffic based on security rules. It acts as a barrier at a network boundary or on a host, inspecting each packet or session and deciding whether to allow or block it according to predefined policies. These rules can consider factors like where the traffic is coming from, where it’s going, what protocol or port is used, and sometimes the data content, especially in more advanced firewalls. The goal is to prevent unauthorized access, malware from entering, or data from leaking out, while still allowing legitimate communication.

Encryption, while essential for protecting data in transit, is not the firewall’s primary function. Encrypting data hides its contents from eavesdroppers, but it doesn’t by itself enforce who may communicate or block harmful traffic. That role—deciding what traffic is allowed or blocked—is what the firewall is designed to do.