What is the role of a firewall in network security?

The primary role of a firewall in network security is to block unwanted access to or from a private network. Firewalls achieve this by implementing predetermined security rules that define which traffic should be allowed through and which should be denied. They inspect incoming and outgoing data packets, evaluating them against these rules. If a data packet matches a rule that allows it, the packet is permitted to pass through; otherwise, it is blocked. This is crucial for protecting networks from unauthorized access, cyber attacks, and various types of malicious entities trying to gain entry.

While encryption of data traffic enhances security by protecting information—a function carried out by other mechanisms—it is not the role of a firewall. Managing IP addresses is usually the function of a DHCP server rather than a firewall. Additionally, while firewalls can contribute indirectly to improved network speed by managing and limiting unwanted traffic, their primary focus is security rather than performance enhancement. Therefore, the correct choice accurately reflects the essential function of a firewall in a network security system.