Understanding Junos Route Preference: Direct, Static, OSPF
A router has a directly connected route to 10.10.10.0/24 on interface ge-0/0/0.0, a static route to the same prefix with next-hop 192.168.1.1, and an OSPF route to the same prefix. Which route is active in the routing table?
Quick Answer
The directly connected route is the active route in the routing table because it carries a Junos route preference of 0, the lowest possible value, making it unbeatable when the interface is up. In Junos, route preference is the tiebreaker when multiple routing protocols learn the same destination; direct routes (preference 0) always win over static routes (preference 5) and OSPF internal routes (preference 10). This concept is a core topic on the JNCIA-Junos exam, often appearing in route preference comparison questions designed to test your understanding of how Junos selects the active route. A common trap is assuming a static route overrides a direct route, but remember that direct routes are always preferred because they represent the interface itself. For a quick memory tip: think of the preference numbers as a race—zero is the starting line, and no other protocol can cross it first.
⚠ Common exam trap
The trap here is that candidates familiar with Cisco IOS might assume static routes (AD 1) are preferred over OSPF (AD 110) but forget that directly connected routes (AD 0) always take precedence, or they might think multiple routes cause a tie or require load-balancing, which is incorrect for a single active route selection.
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 directly connected route
In Junos, the routing table (inet.0) selects the active route based on the route preference (administrative distance). Directly connected routes have a default preference of 0, which is the lowest possible value, making them preferred over static routes (default preference 5) and OSPF routes (preference 10 for intra-area, 150 for external). Therefore, the directly connected route to 10.10.10.0/24 on ge-0/0/0.0 is 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.
- ✗
The static route
Why it's wrong here
Static preference 5 is higher than 0, so loses to direct.
- ✗
No route is active due to multiple routes
Why it's wrong here
The direct route is active; others remain hidden.
- ✗
The OSPF route
Why it's wrong here
OSPF preference 10 is higher than direct and static.
- ✓
The directly connected route
Why this is correct
Direct routes have preference 0, which is the lowest possible, so they are always preferred.
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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Same concept, more angles
4 more ways this is tested on JN0-106
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. 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?
medium- A.Both routes, because they have different protocols.
- B.Neither, because of a conflict.
- ✓ C.The OSPF route, because of lower preference.
- D.The static route, because it is manually configured.
Why C: 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.
Variation 2. What is the default preference value of a directly connected (direct) route in JunOS?
easy- A.10
- B.170
- ✓ C.0
- D.100
Why C: In JunOS, directly connected routes have a default preference value of 0, which is the highest possible preference (lowest numerical value). This ensures that directly connected routes are always preferred over routes learned from any dynamic routing protocol, as they represent interfaces that are directly reachable on the local device.
Variation 3. What is the default preference of a direct route in Junos?
easy- ✓ A.0
- B.10
- C.5
- D.15
Why A: Direct routes in Junos have a default preference of 0, which is the highest possible preference (lowest numerical value). This ensures that directly connected routes are always preferred over any other route type, including static routes (preference 5) and OSPF internal routes (preference 10). The preference value is used by Junos to select the best route when multiple routes exist to the same destination.
Variation 4. A Juniper device receives several routes to the same destination prefix from different routing protocols. Which parameter is used first to select the active route?
easy- ✓ A.Route preference (administrative distance)
- B.Metric
- C.AS path length
- D.Local preference
Why A: When a Juniper device receives multiple routes to the same destination prefix from different routing protocols, the route preference (also known as administrative distance) is the first tiebreaker used to select the active route. Each protocol has a default preference value (e.g., OSPF internal routes have a preference of 10, while static routes have a preference of 5), and the route with the lowest preference is chosen as active. This occurs before any metric or other path attribute is considered.
JA
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.