- A
Next-hop reachability
Why wrong: Reachability determines if a route is active, not its preference.
- B
Number of hops
Why wrong: Hop count is not directly used; metric may represent hop count in some protocols.
- C
Metric (or cost)
Within the same protocol, lower metric is preferred; across protocols, preference is compared first.
- D
Prefix length
Why wrong: Prefix length is used for route lookup, not preference comparison.
- E
Preference value
Lower preference is more preferred, used across protocols.
Question 238 of 514
Route Preference and Metric Comparison in Junos
This JNCIA-JUNOS practice question tests your understanding of routing fundamentals. 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.
Which TWO factors are directly used when comparing route preferences in JunOS? (Choose two.)
Quick Answer
The answer is preference value and metric, as these two factors are directly used when comparing route preferences in JunOS. Preference value is applied first to select the best route when multiple routing protocols provide paths to the same destination, with a lower preference value indicating a more preferred route. If the preference values are equal, the metric—also called cost—is then compared within the same protocol to break the tie, with a lower metric being preferred. On the JNCIA-Junos exam, this concept tests your understanding of how JunOS selects the active route from the routing table, often appearing in multiple-choice questions that distinguish between route selection criteria and forwarding decisions. A common trap is confusing route preference with the longest prefix match, which is used for forwarding lookups, not for comparing route preferences. Remember the mnemonic: Prefer first, then measure—preference decides the protocol winner, metric decides the path within that protocol.
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
✓
Metric (or cost)
In JunOS, route preference (also known as administrative distance) is a value assigned to a routing protocol or a static route to determine which route is preferred when multiple protocols provide a route to the same destination. The route with the lowest preference value is selected. Additionally, when comparing routes from the same protocol, the metric (or cost) is used as the tiebreaker. Therefore, both preference value and metric are directly used in JunOS route preference comparisons.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Next-hop reachability
Why it's wrong here
Reachability determines if a route is active, not its preference.
- ✗
Number of hops
Why it's wrong here
Hop count is not directly used; metric may represent hop count in some protocols.
- ✓
Metric (or cost)
Why this is correct
Within the same protocol, lower metric is preferred; across protocols, preference is compared first.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Prefix length
Why it's wrong here
Prefix length is used for route lookup, not preference comparison.
- ✓
Preference value
Why this is correct
Lower preference is more preferred, used across protocols.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse route preference (administrative distance) with metric or prefix length, but JunOS uses preference first, then metric, while prefix length is only relevant for longest-match forwarding, not for route preference comparison.
Detailed technical explanation
How to think about this question
JunOS uses a two-step route selection process: first, the route with the lowest preference value is chosen among routes from different protocols (e.g., OSPF preference 10 vs. Static preference 5). If multiple routes have the same preference, the metric (cost) is compared, with lower metric preferred. For example, OSPF uses cost based on link bandwidth, while BGP uses MED as a metric. This preference system is defined in the routing table and can be overridden using the 'preference' statement under a routing protocol or static route configuration.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the JNCIA-JUNOS 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.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Routing Fundamentals — study guide chapter
Learn the concepts, then practise the questions
- →
Routing Fundamentals practice questions
Targeted practice on this topic area only
- →
All JNCIA-JUNOS questions
514 questions across all exam domains
- →
Juniper Networks Certified Associate Junos JNCIA-Junos study guide
Full concept coverage aligned to exam objectives
- →
JNCIA-JUNOS practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related JNCIA-JUNOS practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
User Interfaces practice questions
Practise JNCIA-JUNOS questions linked to User Interfaces.
Junos Configuration Basics practice questions
Practise JNCIA-JUNOS questions linked to Junos Configuration Basics.
Operational Monitoring and Maintenance practice questions
Practise JNCIA-JUNOS questions linked to Operational Monitoring and Maintenance.
Routing Fundamentals practice questions
Practise JNCIA-JUNOS questions linked to Routing Fundamentals.
Networking Fundamentals practice questions
Practise JNCIA-JUNOS questions linked to Networking Fundamentals.
Junos OS Fundamentals practice questions
Practise JNCIA-JUNOS questions linked to Junos OS Fundamentals.
JNCIA-JUNOS fundamentals practice questions
Practise JNCIA-JUNOS questions linked to JNCIA-JUNOS fundamentals.
JNCIA-JUNOS scenario practice questions
Practise JNCIA-JUNOS questions linked to JNCIA-JUNOS scenario.
JNCIA-JUNOS troubleshooting practice questions
Practise JNCIA-JUNOS questions linked to JNCIA-JUNOS troubleshooting.
Practice this exam
Start a free JNCIA-JUNOS practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this JNCIA-JUNOS question test?
Routing Fundamentals — This question tests Routing Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Metric (or cost) — In JunOS, route preference (also known as administrative distance) is a value assigned to a routing protocol or a static route to determine which route is preferred when multiple protocols provide a route to the same destination. The route with the lowest preference value is selected. Additionally, when comparing routes from the same protocol, the metric (or cost) is used as the tiebreaker. Therefore, both preference value and metric are directly used in JunOS route preference comparisons.
What should I do if I get this JNCIA-JUNOS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
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 →
Keep practising
More JNCIA-JUNOS practice questions
- A junior engineer needs to collect a snapshot of the current system state, including routing tables, interfaces, and con…
- A network engineer is troubleshooting a connectivity issue and wants to see the active routes in the routing table. Whic…
- You are the network engineer for a mid-sized enterprise with a Juniper MX router running Junos. The router has two uplin…
- Which TWO attributes are used by Junos to select the active route among multiple routes to the same destination?
- What is the default preference of a direct route in Junos?
- A router has two routes to the same destination: one with preference 10 and metric 5, and another with preference 15 and…
Last reviewed: Jul 4, 2026
This JNCIA-JUNOS practice question is part of Courseiva's free Juniper Networks 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 JNCIA-JUNOS 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.