Which of the following best describes a firewall?

• A. A tool that viruses use to propagate
• B. A device that blocks unauthorized access to a network
• C. A type of malware
• D. A method for encrypting sensitive data

Answer: (B)

A firewall is best described as a device that blocks unauthorized access to a network. This is accomplished through a set of defined security rules that regulate inbound and outbound traffic. Firewalls act as a barrier between a trusted internal network and untrusted external sources, filtering traffic to prevent malicious activities and unauthorized access attempts. They play a crucial role in maintaining network security by controlling communication, providing monitoring and logging capabilities, and enforcing security policies.

The other choices do not accurately portray the function or purpose of a firewall. Viruses do not use firewalls; rather, firewalls serve to protect against such malicious software. Additionally, a firewall is not malware; it is a protective feature designed to safeguard networks. Lastly, while encryption is an important aspect of data protection, it is not the primary function of a firewall, which focuses on controlling traffic rather than encrypting data.