What is a common role of network bridges?

Network bridges primarily function to connect local area networks (LANs) that utilize the same communication protocol. This role allows them to effectively divide a network into smaller segments, which can help reduce congestion and improve overall performance. By managing traffic between these segments, bridges can make forwarding decisions based on MAC addresses, thus allowing for more efficient data transfers within the same protocol framework.

When bridges connect LANs of the same type, they help to forward data packets only to the segment where the destination device is located, enhancing network efficiency. This capability is advantageous in environments where different departments might operate on separate segments but need to communicate with each other seamlessly.

In contrast, while other options mention roles that might seem related, they do not accurately define the primary function of network bridges. Bridges do not replace switches; rather, they complement them as they operate at different layers of the OSI model. They are not designed to connect different protocols — this task is typically reserved for routers. Lastly, while they may contribute to a robust network design, the concept of ensuring fault tolerance is more closely associated with redundancies implemented through different network devices rather than the intrinsic role of a bridge itself.