Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A router learns 172.16.40.0/24 from OSPF with AD 110 and metric 20. It also learns the same prefix from EIGRP with AD 90 and feasible distance 30720. Which route is installed?
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.
A
Distractor review
The OSPF route because metric 20 is lower than 30720
OSPF metric is not compared against an EIGRP feasible distance.
B
Best answer
The EIGRP route because its administrative distance is lower
Different protocols are compared by AD first.
C
Distractor review
Both routes because ECMP is automatic across different protocols
Equal-cost load balancing does not happen just because two protocols know the route.
D
Distractor review
Neither route until one is redistributed into the other protocol
Redistribution is not required to install a learned route.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is assuming that the route with the lower metric value is always preferred, regardless of the routing protocol. In this question, the OSPF route has a metric of 20, which seems better than EIGRP's feasible distance of 30720. However, Cisco routers do not compare metrics across different protocols. Instead, they rely on administrative distance to choose the best route. Mistaking metric comparison for cross-protocol route selection can lead to choosing the wrong answer and misunderstanding how Cisco routing decisions work.
Technical deep dive
How to think about this question
Administrative distance (AD) is a Cisco router's method to select the best path when multiple routing protocols provide routes to the same destination. AD is a numeric value that rates the trustworthiness of a routing source; lower values indicate more preferred routes. OSPF has a default AD of 110, while EIGRP internal routes have a default AD of 90. Metrics, such as OSPF cost or EIGRP feasible distance, are only compared when routes come from the same protocol to determine the best path within that protocol. When a router learns the same prefix from different routing protocols, it first compares the administrative distance values. The route with the lowest AD is installed into the routing table, regardless of the metric values of the competing routes. In this scenario, the EIGRP route with AD 90 is preferred over the OSPF route with AD 110, so the EIGRP path is installed. Metrics like OSPF cost 20 or EIGRP feasible distance 30720 are irrelevant in cross-protocol comparisons. A common exam trap is to incorrectly compare metrics across different routing protocols, such as assuming OSPF's metric 20 is better than EIGRP's feasible distance 30720. However, Cisco routers do not compare metrics between protocols; they rely solely on administrative distance for inter-protocol route selection. Practically, this means that even if one protocol reports a seemingly better metric, the route with the lower AD will always be preferred and installed in the routing table.
KKey Concepts to Remember
- Administrative distance determines which route a Cisco router installs when multiple protocols provide the same prefix, with lower AD values preferred.
- EIGRP internal routes have a default administrative distance of 90, which is lower and more trusted than OSPF's default AD of 110.
- Cisco routers compare administrative distance first before considering metrics when selecting routes from different routing protocols.
- Metrics such as OSPF cost or EIGRP feasible distance are only compared among routes learned from the same routing protocol.
- When a router learns the same prefix from OSPF and EIGRP, it installs the route with the lower administrative distance into the routing table.
- Equal-cost multipath (ECMP) load balancing does not occur across different routing protocols without explicit redistribution or configuration.
- Redistribution between routing protocols is not required for a router to install a route learned from either protocol.
- Misinterpreting metrics across protocols is a common exam trap that leads to incorrect route selection assumptions.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
Administrative distance determines which route a Cisco router installs when multiple protocols provide the same prefix, with lower AD values preferred.
What is the correct answer to this question?
The correct answer is: The EIGRP route because its administrative distance is lower — When the same prefix is learned from different routing protocols, the router compares administrative distance first. EIGRP internal routes have AD 90, which beats OSPF AD 110, so the EIGRP path goes into the table.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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