Routing Protocols: Understanding the Functions of a Router

Key Points to Remember about Distance Vector Routing Protocols

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Question

What two things will a router do when running a distance vector routing protocol? (Choose two.)

Answers

Explanations

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A. B. C. D. E.

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Distance vector routing protocols are a type of routing protocol used by routers to determine the best path for routing packets between networks. When running a distance vector routing protocol, a router performs the following two actions:

  1. Updates the routing table based on updates from their neighbors:

In distance vector routing protocols, routers periodically send updates about their routing table to their neighbors, which includes information about the cost or metric of the path to reach a network. When a router receives an update from its neighbor, it updates its own routing table to reflect the new information. This process continues until all routers in the network have updated their routing tables, and all routers have the same information about the network topology.

  1. Uses the shortest-path algorithm to determine the best path:

After updating its routing table based on updates from its neighbors, the router uses the shortest-path algorithm to determine the best path to reach a network. Distance vector routing protocols use a simple algorithm called the Bellman-Ford algorithm to calculate the shortest path. The Bellman-Ford algorithm works by comparing the metric or cost of different paths to reach a network and choosing the path with the lowest metric or cost. This process is repeated for all networks in the routing table.

So, the correct options for the given question are:

D. Update the routing table based on updates from their neighbors. C. Use the shortest-path algorithm to the determine best path.

Option A is incorrect because distance vector routing protocols do not send periodic updates regardless of topology changes. Instead, updates are sent only when there is a change in the network topology.

Option B is incorrect because distance vector routing protocols do not send the entire routing table to all routers in the routing domain. Instead, routers only send updates to their neighbors.

Option E is incorrect because distance vector routing protocols do not maintain the topology of the entire network in their database. Instead, routers only maintain information about the networks that are directly connected to them and the paths to reach other networks based on the updates they receive from their neighbors.