What is the OSPF cost to reach the router A LAN 172.16.1.0/24 from router B?

To determine the OSPF cost to reach the router A LAN 172.16.1.0/24 from router B, it is important to understand how OSPF (Open Shortest Path First) calculates its cost. OSPF utilizes a metric known as cost, which is typically based on the bandwidth of the interfaces involved in the path to the destination. The lower the cost value, the more preferred the route is.

Each interface's cost is calculated using the formula:

OSPF Cost = 100,000,000 / bandwidth (in bps)

This means high-bandwidth links will have a lower cost, making them preferable paths for routing traffic.

In an OSPF network, if you have all the relevant bandwidth information for the links involved between routers B and A, you can sum the costs of each link traversed to reach the destination network. If the answer is indicated as 65, this likely results from summing the calculated costs of all relevant links between router B and router A.

The total cost can also be influenced by factors such as the presence of other OSPF metrics including link types and possible administrative distance adjustments. In this scenario, the total cost of 65 indicates that