The answer is that the SD-WAN rule is configured with a 'set service' that does not match the traffic. This is the most likely reason because SD-WAN rules in FortiOS apply only to traffic matching the specified service (e.g., protocol, port, or application); if the traffic does not match that service, the rule is ignored, and the traffic falls through to a default or different rule that may use port2 regardless of SLA performance. On the Fortinet NSE 7 Advanced Security NSE7 exam, this tests your understanding that SLA-based path selection only occurs within a matched rule—a common trap is assuming that meeting SLA automatically forces traffic to the best path, but the rule must first apply to the traffic. A memory tip: "Match before measure"—the service match must happen before SLA can influence the path.
NSE7 Troubleshooting and Diagnostics Practice Question
This NSE7 practice question tests your understanding of troubleshooting and diagnostics. 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.
An SD-WAN rule has two members: port1 (SLA target latency < 10ms) and port2 (SLA target latency < 20ms). The administrator runs 'diagnose sys sdwan sla-check' and sees that both members meet SLA. However, all traffic is going through port2. What is the MOST likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The SD-WAN rule is configured with 'set service' that does not match the traffic
SD-WAN uses a strategy to select the best path. If the strategy is set to 'best quality' or 'lowest latency', it should prefer the lower latency path. But if the strategy is 'load balancing' or 'manual', it might not automatically prefer port1. The most common cause is that the strategy does not consider SLA, or the load balancing mode distributes traffic regardless of SLA.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 SD-WAN strategy is set to 'load balancing' and the load balancing algorithm is 'spillover'
Why it's wrong here
Spillover uses traffic volume; if port1's volume is low, it may not be used.
✗
The SD-WAN strategy is set to 'manual'
Why it's wrong here
Manual strategy requires explicit rule configuration to use a specific member; if not configured, traffic may not use port1.
✓
The SD-WAN rule is configured with 'set service' that does not match the traffic
Why this is correct
If the rule's service (application) does not match the traffic, the rule is not applied, and traffic uses the default route or another rule.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The 'update-static-route' is disabled on the SD-WAN
Why it's wrong here
This setting affects whether SD-WAN updates static routes, not path selection.
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.
Troubleshooting and Diagnostics — This question tests Troubleshooting and Diagnostics — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The SD-WAN rule is configured with 'set service' that does not match the traffic — SD-WAN uses a strategy to select the best path. If the strategy is set to 'best quality' or 'lowest latency', it should prefer the lower latency path. But if the strategy is 'load balancing' or 'manual', it might not automatically prefer port1. The most common cause is that the strategy does not consider SLA, or the load balancing mode distributes traffic regardless of SLA.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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