Fortify Your Cyber Fortress: Conquer the 2025 NDE Practice Exam! 🚀🔐

The correct choice refers to a firewall technology known as a circuit-level gateway. This type of firewall operates at the session layer of the OSI model, which is layer 5. It establishes a connection between the client and server, allowing traffic to be filtered based on the rules specified for ongoing sessions.

Circuit-level gateways monitor TCP handshakes and determine whether a session is valid. They maintain the state of active sessions and make decisions about which traffic to allow based on that context. This approach allows the firewall to effectively manage connections and provide a level of discretion regarding the session rules set by network administrators.

In contrast, application firewalls operate at the application layer (layer 7) and are designed to filter traffic based on application-specific protocols and message content. Packet filtering firewalls function at the network layer (layer 3) and do so based on IP addresses and port numbers without examining the contents of the packets. Proxy firewalls also work at a higher layer but act as intermediaries between clients and servers, effectively fetching data on behalf of the client and inspecting the contents of the requests and responses.

Thus, the circuit-level gateway correctly fits the criteria of operating at the session layer and filtering traffic based on specified session rules.