NSE4 System and Network Administration Practice Question
A network administrator has configured a static route on a FortiGate with a distance of 10 and a priority of 0. Later, they add another static route to the same destination with a distance of 15 and priority of 0. Which route will be used for traffic forwarding?
⚠ Common exam trap
It's easy for candidates to confuse administrative distance with priority or assume that the most recently added route takes precedence, but FortiGate strictly follows the lower administrative distance rule for 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 route with distance 10 because it has a lower administrative distance
The FortiGate uses administrative distance as the primary metric for route selection when multiple static routes exist to the same destination. A lower administrative distance (10) is preferred over a higher one (15), regardless of the order in which the routes were added. Priority (0 in both cases) is a tie-breaker only when distances are equal, so it does not affect this decision.
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 route with distance 15 because it has a higher priority
Why it's wrong here
Priority is a tiebreaker, not the primary selection criteria. FortiGate first compares administrative distance (AD) and always prefers the lowest AD value; because the routes have different ADs (10 and 15), the one with AD 10 is selected regardless of any priority setting. A higher priority only matters if both routes had the same AD, which is not the case here.
- ✗
Both routes will be used for ECMP load balancing
Why it's wrong here
Equal-cost multi-path (ECMP) load balancing requires routes to have the same administrative distance and metric, making them equally preferred. In this scenario the routes have AD 10 and AD 15, so they are not equal cost; FortiGate selects exactly one route, the one with the lowest AD. The higher-distance route is retained only as a backup and does not participate in load balancing.
- ✗
The route with distance 15 will be used because it was added last
Why it's wrong here
The order in which static routes are added does not influence FortiGate's route selection algorithm. Route preference is determined solely by administrative distance, then by priority/metric as tiebreakers. Even though the AD 15 route was added later, the pre-existing AD 10 route remains the active route because lower AD always wins.
- ✓
The route with distance 10 because it has a lower administrative distance
Why this is correct
Administrative distance is the primary metric FortiGate uses to choose between routes to the same destination, with lower values being more trustworthy. A static route with AD 10 is considered more reliable than one with AD 15, so it is installed in the routing table and used for forwarding. Only if both routes had an equal AD would other factors like priority be considered as a tiebreaker.
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Senior Network & Security Engineer · founder of Courseiva
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