- A
Use Vertex AI Experiments to compare models offline, then deploy the winner
Why wrong: Experiments are for offline evaluation, not online traffic splitting.
- B
Deploy the challenger model to a separate endpoint and use a load balancer to split traffic
Why wrong: Creating a separate endpoint and load balancer adds complexity; Vertex AI native traffic split is simpler.
- C
Update the champion model with a new version and use model version aliases
Why wrong: Version aliases do not control traffic splitting between different models.
- D
Deploy both models to the same endpoint and set traffic_split to 90 for champion and 10 for challenger
Vertex AI traffic_split directly routes the specified percentage of requests to each model.
Question 241 of 1,000
PMLE Serving and Scaling Models Practice Question
This PMLE practice question tests your understanding of serving and scaling models. 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 data scientist wants to perform A/B testing between two model versions deployed on the same Vertex AI endpoint. They need to route 10% of traffic to the challenger model. Which approach should they use?
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
✓
Deploy both models to the same endpoint and set traffic_split to 90 for champion and 10 for challenger
Vertex AI endpoints support traffic splitting directly, allowing you to route a percentage of requests to different model versions deployed on the same endpoint. By setting `traffic_split` to 90 for the champion and 10 for the challenger, the data scientist can perform online A/B testing without additional infrastructure. This is the simplest and most cost-effective approach, as it avoids managing separate endpoints or load balancers.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Vertex AI Experiments to compare models offline, then deploy the winner
Why it's wrong here
Experiments are for offline evaluation, not online traffic splitting.
- ✗
Deploy the challenger model to a separate endpoint and use a load balancer to split traffic
Why it's wrong here
Creating a separate endpoint and load balancer adds complexity; Vertex AI native traffic split is simpler.
- ✗
Update the champion model with a new version and use model version aliases
Why it's wrong here
Version aliases do not control traffic splitting between different models.
- ✓
Deploy both models to the same endpoint and set traffic_split to 90 for champion and 10 for challenger
Why this is correct
Vertex AI traffic_split directly routes the specified percentage of requests to each model.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common trap in Google exams is the misconception that separate endpoints or load balancers are required for A/B testing, when in fact Vertex AI endpoints provide built-in traffic splitting for this exact purpose.
Detailed technical explanation
How to think about this question
Under the hood, Vertex AI endpoints use a weighted round-robin mechanism based on the `traffic_split` dictionary, where the sum of all percentages must equal 100. This feature is implemented at the endpoint's load balancer layer, ensuring consistent routing even during scaling events. A real-world scenario where this matters is gradual rollouts, where you can monitor the challenger's performance with a small traffic slice before promoting it to full production.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Serving and Scaling Models — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this PMLE question test?
Serving and Scaling Models — This question tests Serving and Scaling Models — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy both models to the same endpoint and set traffic_split to 90 for champion and 10 for challenger — Vertex AI endpoints support traffic splitting directly, allowing you to route a percentage of requests to different model versions deployed on the same endpoint. By setting `traffic_split` to 90 for the champion and 10 for the challenger, the data scientist can perform online A/B testing without additional infrastructure. This is the simplest and most cost-effective approach, as it avoids managing separate endpoints or load balancers.
What should I do if I get this PMLE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
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Last reviewed: Jul 4, 2026
This PMLE practice question is part of Courseiva's free Google Cloud 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 PMLE exam.
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