For a Gigabit Ethernet interface with the default reference bandwidth, what is the OSPF cost?

In Open Shortest Path First (OSPF), the cost of a network link is calculated based on the reference bandwidth and the actual bandwidth of the interface. By default, Cisco routers set the reference bandwidth to 100 Mbps.

For a Gigabit Ethernet interface, which operates at 1000 Mbps, the cost is determined using the formula:

OSPF Cost = Reference Bandwidth / Interface Bandwidth

Using the default reference bandwidth:

OSPF Cost = 100 Mbps / 1000 Mbps = 0.1

However, OSPF cost values are typically represented as integers. To convert 0.1 to a more sensible cost value, we multiply by 100 to maintain whole number values, leading us to a standardized OSPF cost of 1 for a Gigabit Ethernet link.

This understanding aligns with OSPF's way of prioritizing higher bandwidth links by assigning lower cost values to them. Thus, a Gigabit Ethernet interface with the default reference bandwidth will have an OSPF cost of 1, making it the correct answer for this question.