The correct answer is that the ECMP algorithm changed from source-IP-based to weighted (hash-based) after the FortiOS upgrade. This is because the replacement of the 'weight' keyword with 'distance' in the 'config router static' command signals a fundamental shift: in older FortiOS versions, the ECMP algorithm used a simple source-IP-based hash to distribute traffic, but starting with FortiOS 6.2, it adopted a weighted hash-based approach where the 'distance' parameter influences route preference while the actual load balancing relies on a hash of packet attributes like source and destination IP. On the Fortinet NSE 4 Network Security Professional exam, this change tests your understanding of how ECMP behavior evolves across firmware versions—a common trap is confusing 'distance' with the old 'weight' logic, but remember that 'distance' now sets administrative preference, not load-balancing weight. A helpful memory tip: think of "distance" as the route's priority ranking, while the hash-based ECMP algorithm does the actual traffic splitting.
NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
After upgrading FortiGate firmware, the administrator notices that the 'config router static' command now shows a new keyword 'distance' instead of 'weight'. The upgrade also changed the ECMP load-balancing behavior. What was the likely change in the ECMP algorithm?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The ECMP algorithm changed from source-IP-based to weighted (hash-based)
The correct answer is A because the upgrade replaced the 'weight' keyword with 'distance' in static routes, indicating a shift from a weighted ECMP algorithm (where routes with lower weight were preferred) to a hash-based algorithm (using source IP by default). This change aligns with FortiOS moving to a more deterministic ECMP load-balancing method, where the 'distance' parameter now influences route selection but ECMP hashing distributes traffic across equal-cost paths based on packet attributes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 ECMP algorithm changed from source-IP-based to weighted (hash-based)
Why this is correct
In older versions, ECMP by default used source-IP; newer versions use a hash of src-dst IP/port.
Related concept
Read the scenario before looking for a memorised answer.
✗
The ECMP algorithm changed from weighted to source-dest-IP
Why it's wrong here
The change was the opposite.
✗
The ECMP algorithm is now configurable via 'config system ecmp'
Why it's wrong here
ECMP algorithm is not separately configurable; it's tied to load-balance method.
✗
The ECMP algorithm changed from source-dest-IP to round-robin
Why it's wrong here
FortiGate has never used round-robin for ECMP.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the 'distance' keyword with administrative distance or assume the ECMP algorithm change is configurable via a dedicated 'ecmp' command, when in fact it is set under 'config system settings' and the default changed from weighted to source-IP-based hashing.
Detailed technical explanation
How to think about this question
In FortiOS, the ECMP algorithm determines how traffic is distributed across multiple equal-cost routes. The default hash algorithm is 'source-ip-based', which uses the source IP address to compute a hash for path selection, ensuring session persistence. The 'weight' parameter in older firmware allowed manual preference among static routes, but the newer 'distance' parameter aligns with standard routing metrics, and ECMP hashing is now independent of route weights, providing more predictable load distribution in multi-WAN or SD-WAN scenarios.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The ECMP algorithm changed from source-IP-based to weighted (hash-based) — The correct answer is A because the upgrade replaced the 'weight' keyword with 'distance' in static routes, indicating a shift from a weighted ECMP algorithm (where routes with lower weight were preferred) to a hash-based algorithm (using source IP by default). This change aligns with FortiOS moving to a more deterministic ECMP load-balancing method, where the 'distance' parameter now influences route selection but ECMP hashing distributes traffic across equal-cost paths based on packet attributes.
What should I do if I get this NSE4 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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