The EIGRP route is installed by default because it has the lower administrative distance. When a router learns the same prefix from multiple routing protocols, it uses administrative distance as the tiebreaker, and EIGRP internal routes are assigned an AD of 90, while OSPF uses an AD of 110. Since a lower AD indicates a more trustworthy source, the router prefers the EIGRP route over the OSPF route. On the CCNA 200-301 v2 exam, this concept often appears in questions about route selection or troubleshooting routing tables, and a common trap is assuming OSPF is always preferred because it is a link-state protocol. Remember that administrative distance overrides protocol sophistication. A useful memory tip is to think of EIGRP as the "90s kid" — it gets the nod with a 90, while OSPF lags behind at 110.
CCNA IP Routing Practice Question
This 200-301 practice question tests your understanding of ip routing. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: when a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
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.
Key principle: When a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route.
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
Protocol type alone does not determine preference.
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
Correct. Lower AD wins between different routing protocols.
Related concept
When a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route.
✗
The route with the lower metric value regardless of protocol
Why it's wrong here
Metrics are not directly compared across different protocols.
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
Both routes are not automatically installed just because the prefix matches.
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
Correct. Lower AD wins between different routing protocols.
✗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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Remember that lower administrative distance values indicate higher preference. Don't confuse protocol complexity with route preference.
Detailed technical explanation
How to think about this question
Administrative distance (AD) is a fundamental concept in Cisco routing that determines the trustworthiness of routing information received from different sources. When a router learns the same IP prefix from multiple routing protocols, it does not compare their metrics directly because each protocol uses different metrics and scales. Instead, it compares the administrative distance values assigned to each protocol. The route with the lowest AD is preferred and installed in the routing table.
EIGRP, a Cisco proprietary routing protocol, assigns an administrative distance of 90 to its internal routes. OSPF, a widely used link-state protocol, assigns an AD of 110. Because 90 is lower than 110, the router prefers the EIGRP route over the OSPF route when both advertise the same prefix. This behavior ensures consistent and predictable route selection in networks running multiple routing protocols.
Metrics such as OSPF cost or EIGRP composite metric are used only to select the best route among multiple routes learned from the same protocol. For example, OSPF compares cost values to choose the best path within OSPF routes. However, when comparing routes from different protocols, these metrics are irrelevant. Administrative distance acts as a universal ranking system to resolve conflicts between protocols.
In practical network design, understanding administrative distance is crucial when redistributing routes between protocols or running multiple routing protocols simultaneously. Network engineers must know that even if OSPF provides a better metric path, the router will still prefer EIGRP routes by default due to AD values. This knowledge helps avoid routing loops, suboptimal routing, and troubleshooting confusion in multi-protocol environments.
KKey Concepts to Remember
When a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route.
EIGRP internal routes have a default administrative distance of 90, which is lower than OSPF's default AD of 110.
Administrative distance is a Cisco-proprietary value that ranks the trustworthiness of routing information from different sources.
Routing metrics such as cost or bandwidth are only compared between routes within the same routing protocol, not across different protocols.
If two routes have the same prefix but come from different protocols, the route with the lowest AD is installed in the routing table.
OSPF is a link-state routing protocol, and EIGRP is an advanced distance-vector protocol, but protocol type alone does not determine route preference.
Routers do not install multiple routes for the same prefix from different protocols by default; only the best route based on AD is installed.
→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.
Key takeaway
When a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review when a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route., then practise related 200-301 questions on the same topic to reinforce the concept.
IP Routing — This question tests IP Routing — When a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 200-301 question wrong?
Review when a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
When a router learns the same IP prefix from multiple routing protocols, it uses administrative distance (AD) to select the best route.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.