Which device is responsible for remembering which devices are connected to each interface?

A switch is designed to manage communication between multiple devices on a local area network (LAN). Its primary function involves creating a dedicated connection between devices on the same network segment, which allows for efficient data transfer. The switch uses a process called MAC address learning, where it keeps a table (often referred to as a MAC address table) that maps the MAC addresses of connected devices to their corresponding ports. This allows the switch to remember which devices are connected to each interface and to forward data packets only to the appropriate destination device rather than broadcasting it to all devices on the network. Consequently, this targeted approach minimizes network congestion and optimizes performance by ensuring that data travels directly to its intended recipient.

In contrast, routers are responsible for directing traffic between different networks rather than managing connections within a single network. Servers provide resources, services, or data to clients and do not keep track of device connections in the same way as switches do. Clients refer to individual devices that use network resources, and they do not hold the functionality of keeping track of network connections either. This delineates why the switch is the device that fits the described role accurately.