NSE4 System and Network Administration Practice Question
A FortiGate is configured with two equal-cost static routes to the same destination network (0.0.0.0/0) via two different ISPs. The administrator wants to use both links simultaneously for load balancing. What must be enabled?
⚠ Common exam trap
Many candidates confuse ECMP with SD-WAN, assuming SD-WAN is mandatory for any multi-WAN load balancing, when in fact ECMP alone suffices for equal-cost static routes without application-aware steering or link health monitoring.
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
✓
ECMP (Equal Cost Multi-Path) routing
Equal Cost Multi-Path (ECMP) routing is the correct feature to enable because it allows a FortiGate to load-balance traffic across multiple static routes that have the same metric (distance) to the same destination (0.0.0.0/0). By default, FortiGate uses a single best route; enabling ECMP distributes sessions across both ISP links based on a hash algorithm (e.g., source-destination IP), achieving simultaneous utilization without requiring dynamic routing protocols.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ECMP (Equal Cost Multi-Path) routing
Why this is correct
FortiGate interprets multiple static routes to the same destination with identical distance and priority as equal-cost paths, installing all of them in the routing table. It then uses a per-destination hash (not per-packet) to select the egress interface for each new session, which preserves session stickiness and enables load sharing across links. This behavior is enabled by default and does not require any additional feature or configuration.
- ✗
SD-WAN
Why it's wrong here
SD-WAN is an overlay controller that aggregates multiple WAN links into a virtual SD-WAN zone and applies health-check and link-quality metrics to steer traffic. Merely configuring two equal-cost static routes does not invoke SD-WAN; the interfaces must be added to a virtual WAN link and SD-WAN rules must be created to override the default routing table. In a pure static-route setup, ECMP handles the load distribution without any SD-WAN involvement.
- ✗
Link load balancing
Why it's wrong here
Link load balancing generally refers to distributing traffic over multiple internet connections using a dedicated load-balancer or HA mode, such as FortiGate active-active clustering with sessions spread across cluster units. It is not intrinsic to routing-table behavior: ECMP is a router-level mechanism, whereas link load balancing is typically a service delivered by an external device or a FortiGate in a different operational mode. The presence of two equal-cost static routes alone does not constitute link load balancing in the HA sense.
- ✗
Policy routing
Why it's wrong here
Policy routing enables an administrator to override the destination-based routing table for specific traffic by matching source addresses, interfaces, protocols, or other attributes and assigning an explicit gateway. ECMP, by contrast, remains destination-based: the FortiGate's forwarding decision for a given same-destination route set uses the equal-cost paths automatically. Policy routes would be a distinct configuration applied before or after the static-route lookup and are not implied by having two equal-cost static routes.
Go deeper
Related to this question
About these practice questions
One of 773 original NSE4 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE4 practice question is part of Courseiva's free Fortinet 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 NSE4 exam.