How is a firewall defined?

How is a firewall defined?

• A. A tool that scans for viruses.
• B. A protocol for data transmission.
• C. A method to compress files.
• D. A logical or physical discontinuity in a network to prevent unauthorized access to data or resources.

Answer: (D)

A firewall is a barrier between trusted and untrusted networks that enforces access control by filtering traffic according to defined rules, blocking unauthorized access while permitting allowed communications. It can be implemented as hardware, software, or a combination, and may perform basic packet filtering or more advanced stateful and application-level inspection. This boundary-setting function is what prevents unauthorized data or resource access, making it the correct description. The other options describe antivirus scanning, a data transmission protocol, or data compression, which do not capture the protective boundary and access-control role of a firewall.

A firewall is a barrier between trusted and untrusted networks that enforces access control by filtering traffic according to defined rules, blocking unauthorized access while permitting allowed communications. It can be implemented as hardware, software, or a combination, and may perform basic packet filtering or more advanced stateful and application-level inspection. This boundary-setting function is what prevents unauthorized data or resource access, making it the correct description. The other options describe antivirus scanning, a data transmission protocol, or data compression, which do not capture the protective boundary and access-control role of a firewall.