(ISC)2 Certified in Cybersecurity Practice Exam

Which of the following best describes a firewall?

1. A system that detects vulnerabilities

2. A tool for monitoring network traffic

3. A barrier that filters incoming and outgoing network traffic

4. A device for physical security

The correct answer is: A barrier that filters incoming and outgoing network traffic

A firewall is best described as a barrier that filters incoming and outgoing network traffic. This definition highlights the primary function of a firewall, which is to control access to and from a network based on predetermined security rules. Firewalls can be hardware-based, software-based, or a combination of both, and they serve to protect internal networks from unauthorized access and potential threats originating from the outside, such as malware or cyberattacks. By establishing a set of rules, firewalls can block unwanted traffic while allowing legitimate communications to pass through. This creates a protective barrier that helps to ensure the integrity and confidentiality of data within the network. Firewalls can also log traffic for analysis, alert administrators to suspicious activity, and facilitate compliance with data protection regulations. While other options reference important aspects of cybersecurity, they do not capture the specific role of a firewall. For instance, a system that detects vulnerabilities refers more to vulnerability scanners which identify weaknesses that could be exploited. Monitoring network traffic implies ongoing observation and analysis of data flows, which is a function often performed by intrusion detection systems or security information and event management (SIEM) tools. The mention of physical security pertains to measures that protect physical assets and infrastructure, which is distinct from the network filtering functions of a firewall.