Which device separates networks into security domains?

A firewall is designed to control network traffic, acting as a barrier between different network segments or between a private network and the internet. It enforces security policies by filtering incoming and outgoing traffic based on predefined rules, effectively separating networks into distinct security domains. An intrusion protection system (IPS) primarily detects and prevents malicious activities within a network, rather than defining security boundaries. A wireless controller manages and centralizes the configuration of multiple access points, while an access point (AP) allows wireless devices to connect to a wired network; neither directly separates networks into security domains.