JN0-106 Routing Fundamentals Practice Question
A network engineer configures a static route to 10.0.0.0/8 with a preference of 20. An OSPF internal route to 10.0.0.0/8 has a default preference of 10. Which route will be active in the routing table?
⚠ Common exam trap
It's easy for candidates to assume static routes always take precedence over dynamic routes, but Junos uses a preference-based selection where a manually configured higher preference (20) makes the static route less preferred than OSPF's default (10).
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
✓
The OSPF route, because of lower preference.
In Junos, the active route in the routing table is determined by the lowest preference value. OSPF internal routes have a default preference of 10, while static routes have a default preference of 5, but here the static route is configured with a preference of 20. Since OSPF's preference (10) is lower than the static route's preference (20), the OSPF route is chosen as active.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Both routes, because they have different protocols.
Why it's wrong here
Even though OSPF and static are different protocols, Junos does not install multiple active routes for the same prefix. The routing table selects at most one active route based on the route's preference value, and the lower-preference OSPF route (10) wins over the static route (20). Thus, having different protocols does not mean both routes are used; only one can be active.
- ✗
Neither, because of a conflict.
Why it's wrong here
There is no conflict because Junos uses deterministic route preference to compare the two entries. An OSPF route to 10.0.0.0/8 has a preference of 10, while the static route has a preference of 20, so OSPF is preferred and installed as active. The static route remains in the routing table as an inactive route, but it does not cause a conflict or prevent the OSPF route from being used.
- ✓
The OSPF route, because of lower preference.
Why this is correct
Junos assigns each routing protocol a default preference, and the route with the lowest preference is chosen as the active route for a destination prefix. OSPF has a default preference of 10, which is lower than the static route's preference of 20. Therefore, the OSPF route is installed in the forwarding table and is the one used for traffic to 10.0.0.0/8.
- ✗
The static route, because it is manually configured.
Why it's wrong here
Manually configuring a static route does not give it priority over a dynamically learned route. Junos compares routes based on their preference values, not on how they were configured. Because OSPF's preference (10) is lower than static's (20), the OSPF route is active, and the static route is not used for forwarding to that prefix.
Visual reference
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.
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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.