NSE7 Advanced Networking and SD-WAN Practice Question
A network engineer is troubleshooting an SD-WAN setup where traffic from a specific subnet is not being load-balanced as expected. The SD-WAN rule uses 'source IP' hashing. The engineer notices that the traffic originates from multiple hosts in the same /24 subnet. What is the most likely cause of poor load distribution?
⚠ Common exam trap
Many candidates assume multiple hosts in the same subnet automatically distribute traffic evenly, forgetting that source IP hashing can produce identical hash values for IPs sharing the same network prefix, leading to poor load balancing.
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
✓
The source IP hashing algorithm causes multiple hosts in the same subnet to map to the same member.
Source IP hashing in SD-WAN uses a hash of the source IP address to select a member for each flow. When multiple hosts reside in the same /24 subnet, their source IPs share the same first 24 bits, which can cause the hash algorithm to map them to the same SD-WAN member if the hash function is not sufficiently granular or if the number of members is small. This results in poor load distribution despite multiple sources.
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 rule is not matching the traffic.
Why it's wrong here
If rule not matching, traffic wouldn't be load-balanced at all.
- ✗
The SD-WAN members have different bandwidths.
Why it's wrong here
Bandwidth differences affect load but not distribution by hash.
- ✗
Traffic is using a single destination IP and port.
Why it's wrong here
Source IP hashing ignores destination/port; source IP alone determines.
- ✓
The source IP hashing algorithm causes multiple hosts in the same subnet to map to the same member.
Why this is correct
Source IP hashing can lead to poor distribution for similar IPs.
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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.