How OSPF Selects Routes
Question
When OSPF learns multiple paths to a network, how does it select a route?
Answers
Explanations
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A. B. C. D.C.
OSPF (Open Shortest Path First) is a link-state routing protocol that uses a cost metric to calculate the shortest path between two routers. When OSPF learns multiple paths to a network, it uses the cost metric to select the best route.
The cost metric in OSPF is calculated based on the bandwidth of the link between two routers. OSPF assumes that higher bandwidth links are better and assigns a lower cost to them. OSPF uses a reference bandwidth value of 100 Mbps to calculate the cost of a link.
When OSPF learns multiple paths to a network, it calculates the cost of each path based on the sum of the costs of all the links in the path. OSPF then selects the path with the lowest cost as the best path to the network.
Option A is incorrect because OSPF does not calculate the route with the lowest bandwidth. Instead, it calculates the cost based on the bandwidth of the link.
Option B is incorrect because OSPF does not count the number of hops between the source router and the destination to determine the route with the lowest metric. Instead, it calculates the cost based on the bandwidth of the link.
Option C is correct because OSPF divides the reference bandwidth of 100 Mbps by the actual bandwidth of the exiting interface to calculate the cost. This results in a lower cost for higher bandwidth links.
Option D is incorrect because OSPF does not use K values to calculate the cost. K values are used in EIGRP (Enhanced Interior Gateway Routing Protocol), another routing protocol used in Cisco networks.
