CompTIA Network+ Practice Test

Routers and Layer 3 switches both primarily serve the function of routing traffic between different IP subnets, which is critical for facilitating communication across diverse network segments. They use Layer 3 information, specifically IP addresses, to determine the best path for forwarding packets. This capability allows them to effectively manage data transmission between various networks, making them essential components in both enterprise environments and broader networking scenarios.

Filtering traffic by port number is a function more relevant to Layer 4 devices, such as firewalls and switches operating at a lower level (Layer 2). Connecting devices within a single network falls under the operations of Layer 2 switches and does not encompass the broader functionality of routing. Lastly, Power over Ethernet (PoE) is a feature associated with certain types of switches that allow them to deliver power alongside data over Ethernet cables, which operates independently of routing capabilities.