CompTIA Network+ Practice Test

What is the primary function of a router in networking?

1. Forwards traffic based on MAC addresses

2. Routes traffic between IP subnets

3. Encrypts data packets during transmission

4. Filters traffic based on application types

The correct answer is: Routes traffic between IP subnets

The primary function of a router in networking is to route traffic between IP subnets. Routers operate at Layer 3 of the OSI model, which is responsible for logical addressing and routing packets between different networks. When a data packet arrives at a router, it examines the destination IP address and determines the best path to forward the packet toward its destination subnet. This process involves consulting the routing table and making decisions based on network conditions, path metrics, and other factors. In contrast, forwarding traffic based on MAC addresses pertains to the function of switches, which operate at Layer 2 of the OSI model. Encrypting data packets during transmission is related to security protocols that ensure data confidentiality and integrity rather than routing, and filtering traffic based on application types is typically associated with firewalls or specific types of advanced networking devices. Thus, the role of the router is distinctly aligned with managing the movement of data packets across different IP networks, which is why routing traffic between IP subnets is its primary function.