NSE4 · Question #22
Examine the two static routes to the same destination subnet 172.20.168.0/24 as shown below; then answer the question following it. config router static edit 1 set dst 172.20.168.0 255.255.255.0 set…
The correct answer is C. The FortiGate sends all the traffic to 172.20.168.0/24 through port1. Given two static routes to the same destination with identical administrative distances but different priorities, the FortiGate will install only the route with the numerically lower priority (higher preference) into the routing table.
Question
Examine the two static routes to the same destination subnet 172.20.168.0/24 as shown below; then answer the question following it. config router static edit 1 set dst 172.20.168.0 255.255.255.0 set distance 20 set priority 10 set device port1 next edit 2 set dst 172.20.168.0 255.255.255.0 set distance 20 set priority 20 set device port2 next end Which of the following statements correctly describes the static routing configuration provided above?
Options
- AThe FortiGate evenly shares the traffic to 172.20.168.0/24 through both routes.
- BThe FortiGate shares the traffic to 172.20.168.0/24 through both routes, but the port2 route will
- CThe FortiGate sends all the traffic to 172.20.168.0/24 through port1.
- DOnly the route that is using port1 will show up in the routing table.
How the community answered
(40 responses)- A3% (1)
- B13% (5)
- C78% (31)
- D8% (3)
Why each option
Given two static routes to the same destination with identical administrative distances but different priorities, the FortiGate will install only the route with the numerically lower priority (higher preference) into the routing table.
FortiGate does not perform equal-cost multipath (ECMP) load balancing if routes have different priorities; it only selects the single most preferred route based on distance then priority.
Load sharing is incorrect here because priorities differ; the route with the lower priority (port1) will be exclusively preferred and used for all traffic.
When multiple routes exist for the same destination, FortiGate first uses administrative distance to determine preference. If distances are equal, it then uses priority, where the numerically lowest priority value indicates the most preferred route, thus the route via port1 with priority 10 will be used exclusively.
Both routes are configured in the routing database, but only the most preferred one (via port1) will be the active route shown in the forwarding information base for sending traffic.
Concept tested: FortiGate static route selection (distance, priority)
Source: https://docs.fortinet.com/document/fortigate/7.4.0/admin-guides/508492/how-traffic-is-processed-by-fortigate
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