A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It allows or blocks specific packets based on these rules, ensuring that only authorized traffic passes through while filtering out potentially harmful data.
A . Switch forwards data between devices on a network but does not filter traffic.
B . Access point connects wireless devices to a network but does not filter packets.
C . Modem provides internet access but lacks packet filtering capabilities.
Reference:
CompTIA Network+ Certification Guide
Official CompTIA Security+ Certification Study Materials