Which of the following can a firewall also function as besides filtering traffic?

A firewall, in addition to filtering traffic, can also function as a router. This is because many modern firewalls incorporate routing capabilities, allowing them to direct traffic between different networks. A firewall that acts as a router can manage how data packets are forwarded across networks while still enforcing security policies, such as access controls and threat detection.

Firewalls are essential for controlling incoming and outgoing network traffic based on predetermined security rules. Integrating routing functions enhances their utility by enabling secure data exchange between internal and external networks. This multifaceted role helps simplify network architecture by combining functions into a single device.

Other choices, such as an application server, access point, and modem, do not accurately describe typical functions of a firewall. An application server primarily hosts applications, an access point provides wireless connectivity, and a modem modulates signals for communication over telecommunications lines. While those devices might coexist within a network, they serve distinct purposes from that of a firewall with routing capabilities.