NSE7 Advanced Networking and SD-WAN Practice Question
Which load balancing algorithm in SD-WAN distributes new sessions based on the source and destination IP addresses, ensuring that all sessions from a given source-destination pair go to the same member?
⚠ Common exam trap
Watch out — candidates often confuse 'Source-dest IP' with 'Sessions' because both involve distribution, but Sessions uses round-robin and does not guarantee source-destination affinity, while Source-dest IP uses a hash to ensure consistent member selection for the same pair.
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
✓
Source-dest IP
The Source-dest IP algorithm in Fortinet SD-WAN uses a hash of the source and destination IP addresses to determine the outbound member for each new session. This ensures that all sessions between the same source-destination pair are consistently forwarded to the same WAN member, preserving flow affinity without requiring session-based state tracking.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Lowest cost
Why it's wrong here
Lowest cost selects the member with the cheapest configured cost metric, so a source-destination pair moves whenever a lower-cost path appears. It fits cost-optimised path selection, not the source-destination hash that pins each pair to one member.
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Volume
Why it's wrong here
Volume balancing assigns members by measured traffic load, so identical source-destination pairs can land on different members as byte counts shift. It suits spreading bulk throughput evenly across links, not preserving session affinity for a persistent flow.
- ✓
Source-dest IP
Why this is correct
Hashing on the source-destination IP pair means every new session between the same two hosts resolves to one member, preserving session stickiness without per-session rebalancing. This satisfies the requirement that all sessions from a given source-destination pair use the same SD-WAN member.
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Sessions
Why it's wrong here
Sessions balancing distributes by active session counts per member, so a source-destination pair can be sent elsewhere once counters change. It suits evening out concurrent connection load, not the source-destination hash that fixes each pair to one member.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.