A router is a type of device that sits on the perimeter of a corporate or home network, where it obtains a public IP address and then generates private IP addresses internally. A router connects two or more networks and forwards packets between them based on routing rules. A router can also provide network address translation (NAT) functionality, which allows multiple devices to share a single public IP address and access the internet. A switch is a type of device that connects multiple devices within a network and forwards packets based on MAC addresses. An intrusion prevention system (IPS) is a type of device that monitors network traffic and blocks or modifies malicious packets based on predefined rules. A gateway is a type of device that acts as an interface between different networks or protocols, such as a modem or a firewall. References: CISA Review Manual (Digital Version), [ISACA Glossary of Terms]