What type of device acts as an interface between a local area network and the internet, using one IP address?

The correct answer is a NAT router, which stands for Network Address Translation router. This type of device is essential in allowing multiple devices within a local area network (LAN) to access the internet using a single public IP address. When devices on the LAN send requests to the internet, the NAT router modifies the outgoing packets to replace the private IP addresses with the public IP address assigned to it. This allows the router to keep track of which private IP address initiated the request, effectively routing the responses back to the correct device within the LAN.

NAT routers enhance security by masking the internal network structure and reducing the number of public IP addresses needed, which is particularly valuable given the limited availability of IPv4 addresses. Additionally, they can provide features like port forwarding and traffic management.

The other options serve different roles in networking. A switch primarily connects devices within a LAN and forwards data based on MAC addresses, but it does not handle internet connectivity or IP address management. A gateway is a broader term that refers to a node that acts as an access point to another network, usually involving protocol translation but not necessarily managing public IP addresses. A modem, on the other hand, modulates and demodulates signals for data transmission over telephone lines or other media, establishing