The answer is source-destination IP hash. This SD-WAN load balancing algorithm is correct because it computes a hash based on both the source and destination IP addresses of each session, ensuring that all traffic sharing the same source-destination IP pair is consistently mapped to the same ISP link. Unlike round-robin or simple source IP hashing, this method preserves session persistence for bidirectional flows, which is critical when an administrator requires that sessions from the same source IP address always use the same link, as stated in the requirement. On the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your understanding of how SD-WAN rules and load balancing algorithms interact with session stickiness—a common trap is confusing source IP hash (which only considers the source) with source-destination IP hash. Remember the mnemonic “Pair to Path”: the source-destination pair locks the path, ensuring consistent link selection for every session between those two hosts.
NSE7 Advanced Networking and SD-WAN Practice Question
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.
An administrator wants to load balance traffic across two ISP links using SD-WAN. The requirement is that sessions from the same source IP address must always use the same ISP link. Which SD-WAN load balancing algorithm should be used?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Source-destination IP
The source-destination IP algorithm uses a hash of source and destination IP addresses to consistently map traffic to the same member. This ensures that all sessions with the same source and destination IP pair go to the same link, meeting the requirement.
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.
✓
Source-destination IP
Why this is correct
This algorithm hashes source and destination IP to consistently select the same member for flows between the same two hosts.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
Sessions
Why it's wrong here
Sessions algorithm distributes sessions evenly, but does not guarantee source IP stickiness.
✗
Volume
Why it's wrong here
Volume algorithm balances based on actual traffic volume, not session persistence.
✗
Spillover
Why it's wrong here
Spillover sends traffic to a secondary link when the primary exceeds a threshold.
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-destination IP — The source-destination IP algorithm uses a hash of source and destination IP addresses to consistently map traffic to the same member. This ensures that all sessions with the same source and destination IP pair go to the same link, meeting the requirement.
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: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 routing to balance traffic across two default routes via two ISPs. The administrator wants to ensure that traffic from the same source-destination pair always uses the same ISP. Which ECMP load balancing method should be configured?
easy
✓ A.source-dest-ip
B.source-ip
C.per-packet
D.session
Why A: ECMP in FortiGate supports several load balancing methods, including source-destination IP hash. To keep traffic from the same source-destination pair consistent, use source-dest-ip hashing. Option A is correct. Option B is for source-only. Option C is session-based. Option D is per-packet (not typical).
Last reviewed: Jun 21, 2026
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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.
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