Quick Answer
The answer is 115. This default administrative distance for IS-IS is set by Cisco to reflect the protocol’s inherent reliability as a link-state interior gateway protocol, which is designed for fast convergence and loop-free path selection within large service provider and enterprise networks. On the Cisco CCNP ENARSI 300-410 exam, you will often encounter this value in questions that test your ability to compare route preferences when multiple routing protocols are redistributed or running simultaneously—a common trap is confusing IS-IS’s 115 with OSPF’s 110 or EIGRP’s 90/170. Remember that IS-IS sits between OSPF and RIP in the trust hierarchy, making 115 a middle-ground value that examiners use to check your recall of protocol-specific metrics. To lock it in, think of the mnemonic: “IS-IS is one-one-five, keeping routes alive.”
This 300-410 practice question tests your understanding of administrative distance. 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 a route learned via the Intermediate System-to-Intermediate System (IS-IS) protocol?
110
Why wrong: 110 is the default AD for OSPF.
115
115 is the correct default AD for IS-IS routes.
120
Why wrong: 120 is the default AD for RIP.
90
Why wrong: 90 is the default AD for EIGRP internal routes.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
115
IS-IS routes have a default administrative distance of 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.
110
115
Why this is correct
115 is the correct default AD for IS-IS routes.
Related concept
Read the scenario before looking for a memorised answer.
120
90
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 300-410 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which 300-410 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Administrative Distance — study guide chapter
Learn the concepts, then practise the questions
Administrative Distance practice questions
Targeted practice on this topic area only
All 300-410 questions
2,152 questions across all exam domains
Cisco CCNP ENARSI 300-410 study guide
Full concept coverage aligned to exam objectives
300-410 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise 300-410 questions linked to Layer 3 Technologies.
Practise 300-410 questions linked to EIGRP Troubleshooting.
Practise 300-410 questions linked to OSPF Troubleshooting (v2/v3).
Practise 300-410 questions linked to BGP Troubleshooting.
Practise 300-410 questions linked to Route Redistribution.
Practise 300-410 questions linked to Policy-Based Routing (PBR).
Practise 300-410 questions linked to VRF-Lite.
Practise 300-410 questions linked to Route Maps and Route Filtering.
Practise 300-410 questions linked to Administrative Distance.
Practise 300-410 questions linked to Route Summarization.
Practise 300-410 questions linked to Bidirectional Forwarding Detection (BFD).
Practise 300-410 questions linked to VPN Technologies.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Administrative Distance — This question tests Administrative Distance — Read the scenario before looking for a memorised answer..
The correct answer is: 115 — IS-IS routes have a default administrative distance of 115.
Identify which 300-410 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Read the scenario before looking for a memorised answer.
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 →
Last reviewed: Jun 18, 2026
This 300-410 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 300-410 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.