Cisco CCNA (200-301)IP ConnectivityEasy
A network engineer issues the `show ip route` command on a router and observes the following entry: `O 172.16.1.0/24 [110/2] via 10.0.0.1, 00:00:25, GigabitEthernet0/0` What does the value `2` in `[110/2]` represent for this OSPF route?
- AThe OSPF priority of the advertising router.
- BThe number of hops to reach the 172.16.1.0/24 network.
- CThe administrative distance of OSPF.
- DThe OSPF cost to reach the 172.16.1.0/24 network.
Show answer & explanationAnswer & explanation
Correct answer: D. The OSPF cost to reach the 172.16.1.0/24 network.
In OSPF routing table entries, the format `[Administrative Distance/Metric]` is used. The first value, `110`, is the administrative distance for OSPF. The second value, `2`, represents the OSPF cost (metric) to reach the destination network 172.16.1.0/24.
Why the other options are wrong
- A. OSPF priority is used in DR/BDR election and is not displayed as part of the route metric.
- B. OSPF uses a cost metric based on bandwidth, not a simple hop count like RIP.
- C. The administrative distance is `110`, which is the first value in the brackets.
OSPF Routing Table Metric
OSPF routes in the routing table display `[Administrative Distance/Cost]`, where the cost is the OSPF metric calculated based on interface bandwidths.
- Administrative Distance (AD) is 110 for OSPF internal routes.
- The cost is an accumulated value from the source to the destination.
- Lower cost is preferred for path selection.
Memory trick: AD then Metric, a route's specific numeric trick.