Which device is primarily responsible for directing data packets based on IP addresses?

The router is primarily responsible for directing data packets based on IP addresses. This function is crucial in networking, as routers operate at Layer 3 of the OSI model, which deals with network layer functionalities. A router examines the destination IP address contained within the data packets and determines the best path for forwarding those packets across different networks. This capability allows routers to connect multiple networks together, enabling devices in different locations to communicate effectively.

In contrast, a bridge operates at Layer 2 of the OSI model and is used to connect two or more networks at the data link layer, primarily focusing on MAC addresses rather than IP addresses. Switches also function at Layer 2 and are primarily responsible for directing data packets within a single local area network (LAN) based on MAC addresses, facilitating communication between devices within that network. Hubs, on the other hand, are basic networking devices that operate at Layer 1, simply relaying data to all connected devices without any intelligent filtering based on addresses. Thus, the router stands out as the device specifically designed for handling IP address-based data packet routing.