Quick Answer
The answer is that the ALB target group weight for the new variant is set to 0. This is the most likely cause because Application Load Balancer traffic distribution is governed by the weights assigned to each target group; a weight of zero directs no traffic to that group, effectively disabling the new variant regardless of its health status. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of how SageMaker A/B testing integrates with ALB routing—a common trap is assuming a health check failure is the culprit, but the question specifies the variant is healthy, so zero weight is the only logical explanation. Remember that ALB weights are explicit: a weight of 0 means zero traffic, while a weight of 1 would send a proportional share. A simple memory tip: "Zero weight, zero traffic—check your weights before you check your health."
This MLS-C01 practice question tests your understanding of machine learning implementation and operations. 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.
A machine learning engineer is deploying a TensorFlow model to an Amazon SageMaker endpoint. The endpoint is behind an Application Load Balancer (ALB) for A/B testing. The engineer notices that the new variant is not receiving any traffic. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The new variant's health checks are failing.
Why wrong: If failing, traffic goes to healthy targets, not zero.
The ALB target group weight for the new variant is set to 0.
Weight of 0 means no traffic is sent.
The model is not compatible with the ALB's protocol.
Why wrong: ALB supports HTTP/HTTPS, TensorFlow models use HTTP.
The ALB is not configured to route to SageMaker endpoints.
Why wrong: ALB can route to any HTTP endpoint.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The ALB target group weight for the new variant is set to 0.
Option A is correct because the ALB target group weight determines traffic distribution. Option B is wrong because routing is based on weights, not health checks if healthy. Option C is wrong because SageMaker endpoint is the target. Option D is wrong because it would cause errors, not zero traffic.
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.
The new variant's health checks are failing.
Why it's wrong here
If failing, traffic goes to healthy targets, not zero.
The ALB target group weight for the new variant is set to 0.
Why this is correct
Weight of 0 means no traffic is sent.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
The model is not compatible with the ALB's protocol.
Why it's wrong here
ALB supports HTTP/HTTPS, TensorFlow models use HTTP.
The ALB is not configured to route to SageMaker endpoints.
Why it's wrong here
ALB can route to any HTTP endpoint.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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 MLS-C01 NAT questions on configuration and troubleshooting.
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FAQ
Machine Learning Implementation and Operations — This question tests Machine Learning Implementation and Operations — Static NAT maps one inside address to one outside address..
The correct answer is: The ALB target group weight for the new variant is set to 0. — Option A is correct because the ALB target group weight determines traffic distribution. Option B is wrong because routing is based on weights, not health checks if healthy. Option C is wrong because SageMaker endpoint is the target. Option D is wrong because it would cause errors, not zero traffic.
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 MLS-C01 NAT questions on configuration and troubleshooting.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 20, 2026
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