ANS-C01 Network Design Practice Question
A company runs a critical application on Amazon EC2 instances in an Auto Scaling group behind a Network Load Balancer (NLB). The application requires that all packets from a given client session are sent to the same target instance for the duration of the session. Which feature should be enabled on the NLB to meet this requirement?
⚠ Common exam trap
Test-takers frequently confuse Proxy Protocol v2 with session persistence, thinking that passing client IP information to the backend automatically ensures stickiness, when in fact Proxy Protocol only provides metadata and does not influence load balancer routing decisions.
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
✓
Enable stickiness using the source IP address
Enabling stickiness using the source IP address on a Network Load Balancer (NLB) ensures that all packets from a given client IP are routed to the same target instance for the duration of the session. This is achieved by the NLB hashing the source IP address (and optionally port and protocol) to consistently select the same target, which meets the requirement for session persistence without relying on application-layer cookies.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable proxy protocol v2
Why it's wrong here
Proxy protocol adds client IP information to the packet, but does not enforce stickiness.
- ✗
Enable cross-zone load balancing
Why it's wrong here
Cross-zone load balancing distributes traffic across all targets, but does not guarantee that packets from a client go to the same target.
- ✓
Enable stickiness using the source IP address
Why this is correct
NLB uses a consistent hash based on source IP, protocol, and port to route packets from the same client to the same target, ensuring session persistence.
- ✗
Configure health checks to mark targets as healthy
Why it's wrong here
Health checks determine target availability, not session stickiness.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services 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 ANS-C01 exam.