The answer is Source-IP-based. This ECMP load balancing method is the correct choice because it uses the source IP address as the sole hash input, ensuring that all packets from a specific source IP are consistently forwarded to the same next hop, even when multiple equal-cost routes exist. On the Fortinet NSE 7 Advanced Security NSE7 exam, this concept tests your understanding of how FortiGate’s ECMP load balancing methods differ—specifically, that Source-IP-based provides per-source persistence, while methods like Round Robin or Weighted would distribute traffic across next hops and break session stickiness. A common trap is confusing Source-IP-based with Source-Destination-IP-based, which hashes both source and destination, so a single source talking to different destinations may still switch next hops. Remember: for source IP persistence, think “one source, one path”—the source alone is the key.
NSE7 Advanced Networking and SD-WAN Practice Question
This NSE7 practice question tests your understanding of advanced networking and sd-wan. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A FortiGate is configured with ECMP load balancing for equal-cost routes. The administrator wants to ensure that all traffic from a specific source IP uses the same next hop. Which ECMP load balancing method should be selected?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Source-IP-based
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Destination-IP-based
Why it's wrong here
Destination-IP-based would hash the destination IP, not the source.
✓
Source-IP-based
Why this is correct
Source-IP-based ECMP hashes the source IP to select a next hop, ensuring all traffic from the same source uses the same path.
Related concept
Static NAT maps one inside address to one outside address.
✗
Weighted random
Why it's wrong here
Weighted random also does not ensure source-IP persistence.
✗
Round-robin
Why it's wrong here
Round-robin does not guarantee persistence per source IP; it cycles through next hops for each packet.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE7 NAT questions on configuration and troubleshooting.
Advanced Networking and SD-WAN — This question tests Advanced Networking and SD-WAN — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Source-IP-based
What should I do if I get this NSE7 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE7 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
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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 FortiGate is configured with ECMP load balancing. What is the default behavior when multiple routes have equal cost?
easy
A.The route with the lowest metric is always preferred
B.The administrator must enable per-packet load balancing
✓ C.Traffic is load balanced across the routes using a hash algorithm
D.All traffic is sent over the first route until it fails
Why C: ECMP (Equal-Cost Multi-Path) by default uses a hash-based method to distribute traffic across the equal-cost paths.
Variation 2. A FortiGate is configured with ECMP load balancing for multiple equal-cost routes. The administrator wants to ensure that all packets belonging to the same session go out the same interface. Which ECMP load balancing method should be used?
hard
A.Weighted
✓ B.Source-dest-IP-based
C.Source-IP-based
D.Spillover
Why B: For ECMP, FortiGate supports source-dest-ip hashing to keep sessions on the same path. Other methods like round-robin may break sessions.
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This NSE7 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 NSE7 exam.
Question Discussion
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