Which type of device sits on the perimeter of a corporate or home network, where it obtains a public IP address and then generates private IP addresses internally?

While a router often functions as a default gateway, "Gateway" is a broader term that can refer to any device that acts as an entry/exit point between networks, and doesn't specifically describe the IP address allocation mechanism.

A switch operates at Layer 2 (Data Link Layer) of the OSI model, connecting devices within the same local network and forwarding traffic based on MAC addresses, without handling public/private IP address translation.

An Intrusion Prevention System (IPS) is a security device that monitors network traffic for malicious activity and can block it, but its primary function is not to obtain public IP addresses or generate private ones for a network.

A router acts as the default gateway for a local network, connecting it to a wider network like the internet. It typically obtains a public IP address from the Internet Service Provider (ISP) and then uses Network Address Translation (NAT) to translate private IP addresses used by devices inside the local network to the single public IP address for external communication.