Which of the following is a function of a firewall?

A firewall serves multiple critical functions in helping to protect network security, and packet filtering is one of its primary roles. This process involves examining data packets that are transmitted between devices on a network. A firewall can analyze these packets against predetermined security rules to determine whether to allow or block the traffic. By filtering packets, a firewall effectively manages network traffic and protects the system from unauthorized access and potential threats.

Packet filtering enhances security by preventing harmful data packets from entering a network, thereby acting as a barrier between secure internal networks and potentially dangerous external networks. This function is particularly crucial given the evolving threat landscape in cybersecurity.

Other functions related to firewalls include network address translation and, to some extent, enabling data encryption. However, these don't primarily represent the core function of firewalls as directly as packet filtering does. Content delivery, on the other hand, is not a function of a firewall; it pertains more to optimizing the delivery of web content to users rather than securing network traffic. Thus, packet filtering is definitive in establishing the foundational operational role of firewalls.