A security solution which filters data packets?

• A. Proxy
• B. Router
• C. Stateful firewall
• D. IDS

Answer: (C)

Filtering data packets is a job of a firewall that uses stateful inspection. A stateful firewall keeps track of active connections and examines each packet in the context of its connection. Because it knows whether a packet belongs to an established session, it can allow or drop packets based on both the current state and the configured rules, providing more precise control over what traverses the network.

A proxy sits between client and server and can filter traffic at the application layer, but it’s not primarily about in‑flight packet filtering. A router mainly forwards packets and can apply basic access controls, yet it doesn’t enforce stateful filtering of connections. An IDS monitors traffic and raises alerts rather than blocking traffic by default.