What is a firewall and how does it contribute to network security?

What is a firewall and how does it contribute to network security?

• A. A DNS service that translates domain names to IP addresses.
• B. A firewall filters network traffic based on rules to block unauthorized access while allowing legitimate communication.
• C. A device that monitors electricity usage.
• D. A software tool for blocking all web traffic.

Answer: (D)

A firewall controls access to a network by examining all traffic crossing the boundary and applying a set of rules that decide what to allow and what to block. This selective filtering helps keep unauthorized people or harmful data from reaching internal systems while still letting legitimate communications through. Firewalls can be hardware devices, software programs, or integrated into routers, and they can operate at different levels—from simple packet filtering to more advanced stateful inspection and application-aware filtering. By enforcing these rules, a firewall reduces the risk of intrusions, malware spread, and policy violations, and it can also log traffic for monitoring and auditing. The other descriptions don’t fit because one refers to translating domain names into IP addresses (DNS), another describes a device that monitors electricity usage, and the last suggests blocking all web traffic, which would disrupt normal, legitimate use and isn’t how firewalls are typically configured.

A firewall controls access to a network by examining all traffic crossing the boundary and applying a set of rules that decide what to allow and what to block. This selective filtering helps keep unauthorized people or harmful data from reaching internal systems while still letting legitimate communications through. Firewalls can be hardware devices, software programs, or integrated into routers, and they can operate at different levels—from simple packet filtering to more advanced stateful inspection and application-aware filtering. By enforcing these rules, a firewall reduces the risk of intrusions, malware spread, and policy violations, and it can also log traffic for monitoring and auditing.

The other descriptions don’t fit because one refers to translating domain names into IP addresses (DNS), another describes a device that monitors electricity usage, and the last suggests blocking all web traffic, which would disrupt normal, legitimate use and isn’t how firewalls are typically configured.