Which feature does a stateful firewall primarily utilize to make decisions?

A stateful firewall primarily utilizes connection states to make decisions about the traffic it processes. This means that it keeps track of the state of active connections, which allows it to determine whether incoming or outgoing packets are part of an established session or if they are new requests that require additional scrutiny.

By monitoring these connection states, the firewall can provide a more dynamic and intelligent approach to security as opposed to merely relying on fixed rules or static criteria. For instance, if a packet arrives that is part of a recognized and established session, it may be allowed through without further checks, whereas a packet that does not match an existing connection would be evaluated against the predefined rules. This capability enables stateful firewalls to effectively manage the complexity of modern network traffic while maintaining security.

Other features like address filtering or traffic volume might play a role in a comprehensive security strategy, but they don't serve as the primary mechanism that stateful firewalls use to handle packets, which fundamentally hinges on tracking and using the information about connection states.