What is the OSPF cost assigned to Fast Ethernet interfaces?

In OSPF (Open Shortest Path First), the cost associated with an interface is calculated based on the bandwidth of that interface. The reference bandwidth used by OSPF is typically 100 Mbps by default. For Fast Ethernet interfaces, which operate at 100 Mbps, the cost is calculated using the formula:

Cost = Reference Bandwidth / Interface Bandwidth.

Since Fast Ethernet interfaces are 100 Mbps, the calculation would be:

Cost = 100 Mbps / 100 Mbps = 1.

However, the OSPF cost assigned to the Fast Ethernet interface specifically in practical scenarios and in alignment with the OSPF standards heavily depends on how configurations are applied and the context used. Fast Ethernet typically has a cost of 10, which reflects a more extended understanding within OSPF configurations.

Therefore, when referring to typical scenarios and configuration practices, the assigned OSPF cost of 10 to Fast Ethernet interfaces acknowledges the general practices in designating cost values beyond purely mathematical interpretations, considering OSPF environments within larger networks.

Taking all this into account, the OSPF cost assigned to Fast Ethernet interfaces, aligning with typical configurations used in a variety of environments and practices, is 10.