easymultiple choiceObjective-mapped

What is the OSPF metric called?

Question 1easymultiple choice

What is the OSPF metric called?

Answer choices

Why each option matters

Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.

Distractor review

Hop count

Hop count is associated with RIP.

Best answer

Cost

Correct. OSPF uses cost.

Distractor review

Distance

Distance is not the OSPF metric name.

Distractor review

Feasible distance

Feasible distance is an EIGRP term.

Common exam trap

Common exam trap: answer the scenario, not the keyword

A common exam trap is confusing OSPF's metric with other routing protocol metrics. For example, hop count is the metric used by RIP, not OSPF. Similarly, 'feasible distance' is a term specific to EIGRP, which can mislead candidates into selecting it as the OSPF metric. Another trap is mistaking administrative distance for metric; administrative distance ranks the trustworthiness of routing protocols, while metric determines the best path within a protocol. Candidates must clearly distinguish that OSPF's metric is called 'cost,' which is bandwidth-based, to avoid selecting incorrect options that sound related but belong to other protocols.

Technical deep dive

How to think about this question

Open Shortest Path First (OSPF) is a widely used link-state routing protocol in Cisco networks, and its routing decisions are based on a metric called 'cost.' The OSPF cost metric is a value assigned to each interface that reflects the overhead required to send packets across that link. By default, Cisco calculates cost as the inverse of the bandwidth of the interface, using the formula: Cost = Reference Bandwidth / Interface Bandwidth, where the reference bandwidth is typically 100 Mbps. For example, a FastEthernet interface (100 Mbps) has a cost of 1, while a Gigabit Ethernet interface (1000 Mbps) has a cost of 1/10th, which Cisco rounds to 1 as well, but can be adjusted by changing the reference bandwidth. This cost metric allows OSPF to select the most efficient path to a destination by summing the costs of all outgoing interfaces along a route and choosing the path with the lowest total cost. Unlike distance-vector protocols such as RIP, which use hop count as a metric, OSPF's cost metric provides a more granular and bandwidth-aware path selection. EIGRP, another Cisco routing protocol, uses a composite metric including bandwidth and delay, and terms like 'feasible distance' are specific to EIGRP, not OSPF. Understanding OSPF cost is critical for network engineers to optimize routing and ensure efficient traffic flow in Cisco environments.

KKey Concepts to Remember

OSPF metric is called cost
Cost is based on interface bandwidth
OSPF uses cost to determine shortest path
RIP uses hop count as metric, not OSPF
EIGRP uses feasible distance, not cost
Administrative distance differs from metric
Metric influences OSPF route selection

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.