- A
Configure the primary with a lower preference and the backup with a higher preference.
Lower preference is more preferred; when primary fails, backup takes over.
- B
Configure the primary with a higher preference and the backup with a lower preference.
Why wrong: This would make the backup the primary, opposite of the requirement.
- C
Configure two static routes with equal preferences; the active route will be chosen based on next-hop IP.
Why wrong: Equal preferences would cause both to be installed, but failover behavior is not guaranteed as expected.
- D
Configure the routes with the same preference but use a policy to set metric.
Why wrong: Metric is not used for static route selection; preference is the only factor.
Question 398 of 514
Configuring Static Route Failover with Preference in Junos
This JNCIA-JUNOS practice question tests your understanding of routing fundamentals. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
An engineer is configuring multiple static routes to the same destination for redundancy. The primary link uses 192.168.1.1 and the backup uses 192.168.2.1. They want the backup to be used only when the primary next-hop is unreachable. Which configuration is correct?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Quick Answer
The correct configuration is to assign the primary static route a lower preference value and the backup a higher preference value. This works because Junos uses the preference metric to select among multiple routes to the same destination; the route with the lowest preference is installed in the forwarding table first. When the primary next-hop at 192.168.1.1 becomes unreachable, the route is withdrawn, and the backup route with the higher preference automatically takes over, providing deterministic failover. On the JNCIA-Junos exam, this concept tests your understanding of static route preference as a tiebreaker for redundancy, often appearing in scenario-based questions where you must avoid the common trap of confusing preference with metric or assuming a higher preference is better. Remember the simple mnemonic: lower preference wins, so the primary gets the lower number to be preferred first.
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
✓
Configure the primary with a lower preference and the backup with a higher preference.
Option A is correct because in JUNOS, a lower preference value indicates a more preferred route. By setting the primary next-hop (192.168.1.1) with a lower preference (e.g., 5) and the backup next-hop (192.168.2.1) with a higher preference (e.g., 10), the primary route is installed in the routing table. If the primary next-hop becomes unreachable, the route is withdrawn, and the backup route with the higher preference is then installed, providing redundancy.
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.
- ✓
Configure the primary with a lower preference and the backup with a higher preference.
Why this is correct
Lower preference is more preferred; when primary fails, backup takes over.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure the primary with a higher preference and the backup with a lower preference.
Why it's wrong here
This would make the backup the primary, opposite of the requirement.
- ✗
Configure two static routes with equal preferences; the active route will be chosen based on next-hop IP.
Why it's wrong here
Equal preferences would cause both to be installed, but failover behavior is not guaranteed as expected.
- ✗
Configure the routes with the same preference but use a policy to set metric.
Why it's wrong here
Metric is not used for static route selection; preference is the only factor.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse preference with metric, thinking that equal preferences with a policy can achieve failover, but JUNOS does not use metric for static route selection, and without a difference in preference, both routes remain in the table without automatic failover based on next-hop reachability.
Detailed technical explanation
How to think about this question
In JUNOS, the route preference (administrative distance) is a 32-bit value where lower is better. When a static route is configured with a specific next-hop, JUNOS monitors the next-hop reachability via ARP (for directly connected next-hops) or routing table resolution (for indirect next-hops). If the primary next-hop becomes unreachable, the route is removed from the routing table, allowing the backup route with a higher preference to be installed. This behavior is distinct from Cisco IOS, where floating static routes require a higher administrative distance on the backup route.
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.
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.
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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: Configure the primary with a lower preference and the backup with a higher preference. — Option A is correct because in JUNOS, a lower preference value indicates a more preferred route. By setting the primary next-hop (192.168.1.1) with a lower preference (e.g., 5) and the backup next-hop (192.168.2.1) with a higher preference (e.g., 10), the primary route is installed in the routing table. If the primary next-hop becomes unreachable, the route is withdrawn, and the backup route with the higher preference is then installed, providing redundancy.
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.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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