Quick Answer
The answer is the source-destination IP load balancing algorithm. This algorithm works by computing a hash of both the source and destination IP addresses from each new session, then using that hash to consistently map the session to the same SD-WAN member. Because the hash is deterministic for any given source-destination pair, all traffic between those two endpoints—whether it’s a single TCP connection or multiple related sessions—will always be forwarded through the same link, preventing asymmetric routing and preserving state for firewalls or application proxies. On the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your understanding of how SD-WAN rules select paths for stateful traffic; a common trap is confusing this algorithm with the simpler “source IP” or “destination IP” algorithms, which only hash one side of the conversation. Remember the memory tip: “Source-dest IP keeps the pair together—same two IPs, same member forever.”
This NSE7 practice question tests your understanding of advanced networking and sd-wan. 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.
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?
Lowest cost
Why wrong: Lowest cost uses cost metric.
Volume
Why wrong: Volume distributes based on bandwidth usage.
Source-dest IP
Hashes source and destination IP.
Sessions
Why wrong: Sessions distributes based on number of sessions.
Answer choices
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-destination IP algorithm uses a hash of source and destination IP to consistently select the same member for the same pair, which is useful for stateful applications or to avoid asymmetric routing.
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
For each option: why learners choose it and why it is or isn't the right answer here.
Lowest cost
Why it's wrong here
Lowest cost uses cost metric.
Volume
Why it's wrong here
Volume distributes based on bandwidth usage.
Source-dest IP
Why this is correct
Hashes source and destination IP.
Related concept
Static NAT maps one inside address to one outside address.
Sessions
Why it's wrong here
Sessions distributes based on number of sessions.
Common exam traps
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
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.
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
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
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.
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FAQ
Advanced Networking and SD-WAN — This question tests Advanced Networking and SD-WAN — Static NAT maps one inside address to one outside address..
The correct answer is: Source-dest IP — The source-destination IP algorithm uses a hash of source and destination IP to consistently select the same member for the same pair, which is useful for stateful applications or to avoid asymmetric routing.
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.
Static NAT maps one inside address to one outside address.
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Same concept, more angles
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. Which SD-WAN load balancing algorithm is best for ensuring that all traffic from a specific source-destination pair uses the same WAN link?
easyVariation 2. A FortiGate is configured with SD-WAN using load balancing algorithm 'source-dest-ip'. What is the primary characteristic of this algorithm?
easyWhy D: The source-dest-ip algorithm uses a hash of source and destination IP addresses to select the outgoing interface, ensuring that all packets of a given session go through the same link.
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Last reviewed: Jun 21, 2026
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.
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