Which is a characteristic of a next-generation firewall?

Next-generation firewalls (NGFWs) are advanced security devices that go beyond traditional port and protocol inspection. A key characteristic is their ability to provide intrusion prevention (IPS) capabilities, detecting and blocking known and unknown threats, including malware and exploits, based on signatures, behavioral analysis, and reputation. "Only required at the network perimeter" is incorrect because NGFWs are increasingly deployed internally (east-west traffic) for segmentation and deeper threat inspection. "Required in each layer of the network" is too absolute; while beneficial, it's not a strict requirement for every layer. "Filters traffic using Layer 3 and Layer 4 information only" describes traditional firewalls; NGFWs perform deep packet inspection up to Layer 7 (application layer) and use context beyond just IP addresses and ports.