- A
Increase the preference of the BGP default routes to 180 so that the static default is always preferred.
Why wrong: This would make the static default always active, preventing failover between ISPs.
- B
Configure a routing policy on R2 to reject the default route from ISP-B, forcing all traffic through R1.
Why wrong: This would eliminate redundancy.
- C
Remove the static default route and rely on OSPF to propagate a default route from the router with the active BGP session.
Why wrong: Without any static default, if both BGP sessions fail, there is no default route.
- D
Configure the static default route with a preference of 180 so that the BGP default routes (pref 170) are preferred when available.
This ensures BGP default is used when up, and OSPF routes to R2's default become active when R1's BGP is down.
Quick Answer
The correct answer is to configure the static default route with a preference of 180. This works because the floating static route preference determines which route is installed in the routing table when multiple routes to the same destination exist; a lower preference value is more preferred. Here, the static default route’s preference of 5 made it win over the BGP default (preference 170), so traffic never used the BGP-learned route. By raising the static route’s preference to 180—higher than BGP’s 170—you create a true backup: the BGP default is chosen when available, and the static route only activates when BGP fails. On the JNCIA-Junos exam, this tests your understanding of route preference as a tie-breaking mechanism, often with a trap where candidates forget that a static route’s default preference (5) overrides dynamic protocols. A helpful memory tip: “Static is king by default—raise its preference to make it a backup.”
JNCIA-JUNOS Routing Fundamentals Practice Question
This JNCIA-JUNOS practice question tests your understanding of routing fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Your company operates a dual-homed network with two Juniper MX routers (R1 and R2) each connected to a different ISP. R1 uses BGP to receive a default route from ISP-A (preference 170), and R2 uses BGP to receive a default route from ISP-B (preference 170). Additionally, both routers have a static default route pointing to a local next-hop (192.0.2.1) with preference 5 for backup. R1 and R2 are connected via an internal link (10.0.0.0/30) and run OSPF to exchange internal routes. You notice that traffic from internal hosts is always exiting via R1's ISP-A link, even when R1's BGP session to ISP-A goes down. The OSPF routes are preferred. You want traffic to fail over to R2's ISP-B link when R1 loses its BGP default. Which configuration change should you make?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"always"Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
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 static default route with a preference of 180 so that the BGP default routes (pref 170) are preferred when available.
Option D is correct because the static default route currently has a preference of 5, making it preferred over the BGP default (preference 170) even when the BGP route is available. By raising the static default's preference to 180 (higher than BGP's 170), the BGP default will be chosen when present, and the static default will only be used as a backup when BGP is unavailable. This ensures traffic fails over to R2's ISP-B link when R1 loses its BGP default, as OSPF will propagate the default from R2.
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.
- ✗
Increase the preference of the BGP default routes to 180 so that the static default is always preferred.
Why it's wrong here
This would make the static default always active, preventing failover between ISPs.
- ✗
Configure a routing policy on R2 to reject the default route from ISP-B, forcing all traffic through R1.
Why it's wrong here
This would eliminate redundancy.
- ✗
Remove the static default route and rely on OSPF to propagate a default route from the router with the active BGP session.
Why it's wrong here
Without any static default, if both BGP sessions fail, there is no default route.
- ✓
Configure the static default route with a preference of 180 so that the BGP default routes (pref 170) are preferred when available.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume static routes with a lower preference are always better, but the question requires the static route to act as a backup, so it must have a higher preference than the BGP route to be less preferred when the BGP route is available.
Detailed technical explanation
How to think about this question
In JUNOS, route preference (administrative distance) determines which route is installed in the forwarding table when multiple routes to the same destination exist. BGP defaults have a preference of 170, while static routes default to 5. By setting the static default to 180, you ensure BGP is always preferred when available. Additionally, OSPF can propagate a default route using the 'default-information originate' policy, which would have a preference of 150 (external type 2) or 10 (if configured as a stub area default), but this requires explicit configuration and does not automatically occur when a BGP session goes down.
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 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.
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 static default route with a preference of 180 so that the BGP default routes (pref 170) are preferred when available. — Option D is correct because the static default route currently has a preference of 5, making it preferred over the BGP default (preference 170) even when the BGP route is available. By raising the static default's preference to 180 (higher than BGP's 170), the BGP default will be chosen when present, and the static default will only be used as a backup when BGP is unavailable. This ensures traffic fails over to R2's ISP-B link when R1 loses its BGP default, as OSPF will propagate the default from R2.
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: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
1 more ways this is tested on JNCIA-JUNOS
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An engineer wants to configure a static route that will be used only if the primary route (learned via OSPF) becomes unavailable. Which feature should be used?
easy- ✓ A.Floating static route with a higher preference.
- B.Static route with a lower metric.
- C.Reverse path forwarding.
- D.Routing policy.
Why A: Option B is correct because a floating static route uses a higher preference so it is less preferred than OSPF and only becomes active when OSPF fails. Option A is wrong because metric is not comparable across protocols. Option C is wrong because RPF is unrelated. Option D is wrong because routing policy is too broad and not the specific feature.
Last reviewed: Jun 11, 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.
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