Which of the following best describes a firewall?

• A. A collection of software that runs malware
• B. A system designed to prevent unauthorized access to or from a network
• C. A tool that enhances user productivity
• D. An application used for data analysis

Answer: (B)

A firewall is best described as a system designed to prevent unauthorized access to or from a network. Its primary function is to monitor and control incoming and outgoing network traffic based on predetermined security rules. By acting as a barrier between a trusted internal network and untrusted external networks (like the internet), a firewall helps to safeguard sensitive data and resources from potential threats.

Firewalls can be hardware-based, software-based, or a combination of both, and they play a crucial role in implementing a network security policy. They examine packets of data that attempt to enter or leave the network and can block or allow traffic based on specific criteria. This filtering capability is essential for protecting systems from various cyber threats, including intrusions and unauthorized access attempts.

In contrast, the other options do not accurately represent the function of a firewall. The first option suggests a collection of software that runs malware, which is fundamentally opposed to what a firewall aims to do. The third option, about enhancing user productivity, does not relate to firewall characteristics; productivity tools are unrelated to network security. Lastly, the fourth option regarding data analysis applications is also irrelevant, as it does not pertain to the core functionalities or purpose of a firewall.