CCNA IP Routing Practice Question
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
⚠ Common exam trap
Remember that lower administrative distance values indicate higher preference. Don't confuse protocol complexity with route preference.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The EIGRP route because it has the lower administrative distance
When identical prefixes are learned from different routing protocols, the router compares administrative distance first. EIGRP internal routes use AD 90, while OSPF uses AD 110.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The OSPF route because OSPF is link-state
Why it's wrong here
Selecting OSPF simply because it is link-state ignores how routing preference actually works. Link-state vs distance-vector describes how routes are computed, not which is preferred. Cisco routers compare administrative distance, not protocol type, so OSPF's higher AD (110) loses to EIGRP's 90 regardless of OSPF's link-state advantages.
When this WOULD be correct
In a different scenario where the question specifies that OSPF is configured with a lower administrative distance than EIGRP, or if both protocols are configured with the same administrative distance, then the OSPF route would be installed by default due to its link-state nature.
- ✓
The EIGRP route because it has the lower administrative distance
Why this is correct
The EIGRP route is installed because EIGRP has an administrative distance of 90, while OSPF uses 110. When a router receives the same prefix from different routing protocols, the lower AD is selected as the best path. Protocol-specific metrics are never compared across protocols; AD is the first tie-breaker.
- ✗
The route with the lower metric value regardless of protocol
Why it's wrong here
Lower metric never decides between OSPF and EIGRP because their metrics are not comparable — OSPF uses cost derived from bandwidth, while EIGRP uses a composite of bandwidth, delay, load, and reliability. Metrics only matter when comparing routes from the same protocol. A router first applies administrative distance to pick the protocol, then compares metrics only within that protocol.
When this WOULD be correct
If the exam question specified that the router should select the route based on the lowest metric value without considering administrative distances, then this option would be correct. For example, a question might ask which route would be chosen if both protocols had the same administrative distance.
- ✗
Both routes are always installed
Why it's wrong here
A router installs only the single best route for each prefix in its routing table, not every route learned from every protocol. Both OSPF and EIGRP may feed the RIB, but the one with the lowest AD is chosen; the other is kept in the topology table but not installed. Only equal-cost paths from the same protocol and same metric could both be installed.
When this WOULD be correct
If the exam question specified a scenario where a router is configured to use a specific routing policy that allows multiple routes to be installed for the same prefix, such as with route redistribution or a specific configuration that permits equal-cost multipath (ECMP), then this option would be correct.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The EIGRP route because it has the lower administrative distanceCorrect answer▾
Why this is correct
The EIGRP route is installed because EIGRP has an administrative distance of 90, while OSPF uses 110. When a router receives the same prefix from different routing protocols, the lower AD is selected as the best path. Protocol-specific metrics are never compared across protocols; AD is the first tie-breaker.
✗The OSPF route because OSPF is link-stateWrong answer — click to see why▾
Why this is wrong here
The type of routing protocol (link-state vs. distance vector) does not determine route preference when comparing routes from different protocols. Route selection is based on administrative distance, not protocol characteristics.
★ When this WOULD be the correct answer
In a different scenario where the question specifies that OSPF is configured with a lower administrative distance than EIGRP, or if both protocols are configured with the same administrative distance, then the OSPF route would be installed by default due to its link-state nature.
Why candidates choose this
Students may think that link-state protocols like OSPF are inherently more reliable or preferred over distance-vector protocols like EIGRP, but this is not how route selection works.
✗The route with the lower metric value regardless of protocolWrong answer — click to see why▾
Why this is wrong here
Metrics are only comparable within the same routing protocol. Different protocols use different metrics (e.g., OSPF uses cost, EIGRP uses composite metric), so they cannot be directly compared. Administrative distance is used to choose between protocols.
★ When this WOULD be the correct answer
If the exam question specified that the router should select the route based on the lowest metric value without considering administrative distances, then this option would be correct. For example, a question might ask which route would be chosen if both protocols had the same administrative distance.
Why candidates choose this
Students often confuse metric and administrative distance, thinking that a lower metric always wins regardless of protocol, but metric comparison is only valid within the same protocol.
✗Both routes are always installedWrong answer — click to see why▾
Why this is wrong here
By default, a router installs only the best route (lowest AD) for a given prefix into the routing table. Both routes are not installed unless features like equal-cost multipath or policy routing are configured, which is not the case here.
★ When this WOULD be the correct answer
If the exam question specified a scenario where a router is configured to use a specific routing policy that allows multiple routes to be installed for the same prefix, such as with route redistribution or a specific configuration that permits equal-cost multipath (ECMP), then this option would be correct.
Why candidates choose this
Some students may think that multiple routes to the same destination are always installed for redundancy, but the routing table only contains the best route unless explicitly configured otherwise.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
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Key term
Administrative distance
Administrative distance is a number that a router uses to decide which routing protocol's route to trust when it learns about the same destination from multiple different routing protocols.
Key term
EIGRP
EIGRP is an advanced distance-vector routing protocol that uses bandwidth and delay by default to find the best path for data packets across a computer network.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.