Quick Answer
The answer is 110. This is the default administrative distance for OSPF routes on a typical Cisco router, meaning the router trusts OSPF-learned routes over protocols with a higher AD, such as RIP at 120, but defers to routes from protocols with a lower AD, like a static route at 1 or EIGRP at 90. Administrative distance is a trustworthiness metric used to select the best path when multiple routing protocols know the same destination; a lower value is always preferred. On the CompTIA Network+ N10-009 exam, you may be asked to compare these default AD values to determine which route a router will install, so a common trap is confusing OSPF’s 110 with IS-IS’s 115 or forgetting that EIGRP internal routes (90) are more trusted than OSPF. A helpful memory tip: think of OSPF as “one-ten” and remember that it sits right in the middle of the routing protocol hierarchy—more trusted than RIP (120) but less trusted than EIGRP (90).
This N10-009 practice question tests your understanding of network operations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
What is the default administrative distance for OSPF routes on a typical Cisco router?
90
Why wrong: 90 is the default AD for EIGRP (internal) routes, not OSPF.
100
Why wrong: 100 is the default AD for IGRP (legacy Cisco protocol), not OSPF.
110
OSPF uses an AD of 110 by default, making it more trusted than RIP (120) but less than EIGRP (90) and external EIGRP (170).
120
Why wrong: 120 is the default AD for RIP (Routing Information Protocol), not OSPF.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
110
Option C is correct because the default administrative distance for OSPF routes on a Cisco router is 110. Administrative distance is a trustworthiness metric used to select the best route when multiple routing protocols provide a route to the same destination; a lower value is preferred. OSPF's default AD of 110 is higher than that of static routes (1) and EIGRP (90/170), but lower than RIP (120) and IS-IS (115).
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
90
100
110
120
Common exam traps
CompTIA often tests the default administrative distances for OSPF, EIGRP, and RIP, and the trap here is confusing OSPF's AD of 110 with EIGRP's AD of 90 or RIP's AD of 120, especially since OSPF is a link-state protocol while EIGRP is a hybrid, leading candidates to misremember the values.
Detailed technical explanation
The administrative distance is a Cisco-proprietary mechanism not defined in any RFC; it is a local router setting used to arbitrate between routes from different sources. For OSPF, the default AD of 110 applies to both intra-area and inter-area routes, but OSPF external routes (type 1 and type 2) also use 110 by default. In real-world scenarios, if a router learns the same prefix via OSPF (AD 110) and RIP (AD 120), the OSPF route will be installed in the routing table, even if the RIP route has a better metric.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
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FAQ
Network Operations — This question tests Network Operations — Read the scenario before looking for a memorised answer..
The correct answer is: 110 — Option C is correct because the default administrative distance for OSPF routes on a Cisco router is 110. Administrative distance is a trustworthiness metric used to select the best route when multiple routing protocols provide a route to the same destination; a lower value is preferred. OSPF's default AD of 110 is higher than that of static routes (1) and EIGRP (90/170), but lower than RIP (120) and IS-IS (115).
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.
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