How does router-by-router next-hop decision increase routing fault tolerance?

How does router-by-router next-hop decision increase routing fault tolerance?

• A. It ensures the path is fixed
• B. It duplicates packets along all possible routes
• C. It requires every router to fail before changing path
• D. It allows each router to pick a currently working path.

Answer: (D)

Allowing each router to pick a next hop that is currently reachable lets the network adapt to failures by dynamically rerouting around outages. When a link or node fails, that router can choose a different neighbor that still progresses toward the destination, so traffic keeps flowing even as conditions change. This decentralized, up-to-date decision-making provides fault tolerance because there are multiple viable paths and routers can switch to whichever one is working now. The other ideas would lock in a single path, flood the network with duplicate packets, or wait for everyone to fail before changing, which either wastes resources or leaves traffic unprotected against outages.

Allowing each router to pick a next hop that is currently reachable lets the network adapt to failures by dynamically rerouting around outages. When a link or node fails, that router can choose a different neighbor that still progresses toward the destination, so traffic keeps flowing even as conditions change. This decentralized, up-to-date decision-making provides fault tolerance because there are multiple viable paths and routers can switch to whichever one is working now. The other ideas would lock in a single path, flood the network with duplicate packets, or wait for everyone to fail before changing, which either wastes resources or leaves traffic unprotected against outages.