JN0-106 Routing Fundamentals Practice Question
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?
⚠ Common exam trap
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. With equal preferences, both static routes are installed and load-balanced, so the backup is used even when the primary is reachable. To ensure the backup is only used when the primary fails, configure the primary with a lower preference and the backup with a higher preference.
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.
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 If the primary next-hop becomes unreachable, the route is withdrawn, and the backup route with the higher preference is then installed, providing redundancy.
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
In Junos, route preference acts as an administrative distance, and a numerically lower value is always preferred. Assigning the primary static route a lower preference ensures it is installed in the routing and forwarding tables, while the higher-preference backup remains inactive. If the primary's next-hop becomes unreachable, the primary route is withdrawn and the backup is automatically promoted, providing the required failover behavior.
- ✗
Configure the primary with a higher preference and the backup with a lower preference.
Why it's wrong here
Because a lower preference is always preferred, giving the backup a lower preference would cause the backup to become the active route immediately, while the intended primary with a higher preference is never used. This completely reverses the intended design: traffic always traverses the backup, and when the primary's next-hop fails, there is no failover to the primary because it was never active. The primary would only be used if the backup fails, which is not the stated requirement.
- ✗
Configure two static routes with equal preferences; the active route will be chosen based on next-hop IP.
Why it's wrong here
Two static routes with equal preference are both installed in the Junos routing table as equal-cost next-hops, and forwarding traffic is load-balanced across them rather than selecting one as a primary. Junos does not choose an active route based on next-hop IP for static routes; both remain active simultaneously. While this may provide redundancy, it does not create a deterministic primary/backup relationship or guarantee controlled failover in the order the engineer likely expects.
- ✗
Configure the routes with the same preference but use a policy to set metric.
Why it's wrong here
In Junos, static route selection is determined solely by the preference value; there is no meaningful metric field for static routes that a policy can modify to influence route choice. Configuring two static routes with the same preference and using a policy to set a metric will have no effect on which route is installed, so both routes remain active and the configuration does not produce a primary/backup relationship. This approach is invalid for implementing the engineer's failover requirement.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This JN0-106 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 JN0-106 exam.