The answer is to use a high-memory machine type like n1-highmem-16 to reduce memory pressure. This resolves the GPU utilization bottleneck on Vertex AI because the NLP model’s 2 GB memory footprint is causing excessive GPU idle time as the system swaps data between RAM and GPU memory, saturating the GPU at over 90% while CPU and memory remain below 50%. On the Google Professional Machine Learning Engineer exam, this scenario tests your understanding that GPU utilization bottlenecks often stem from insufficient host memory, not GPU compute power—a common trap where candidates mistakenly scale replicas or CPU cores. The key insight is that Vertex AI Prediction endpoints require balanced resources; here, adding memory per replica allows the GPU to process batches without stalling. Memory tip: think “GPU hungry, memory shy”—when GPU is pegged but CPU is low, feed it more RAM, not more replicas.
PMLE Serving and scaling models Practice Question
This PMLE practice question tests your understanding of serving and scaling models. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Your organization has a large production system that uses Vertex AI Prediction for an NLP model with a 2 GB memory footprint. The endpoint is configured with 5 replicas, each using an n1-standard-4 with a single T4 GPU. Recently, you observed an increase in 503 errors during peak hours. Cloud Monitoring shows that GPU utilization is consistently above 90% across all replicas, while CPU and memory are below 50%. You have already increased the max replicas to 10, but the errors persist because the increased replicas also become saturated. What should you do to resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a high-memory machine type like n1-highmem-16 to reduce memory pressure.
Option D is correct because CPU bottlenecks cause high latency; switching to a machine type with more CPU cores (e.g., n1-highcpu-16) reduces CPU contention. Option A adds memory but not CPU. Option B uses more replicas but each already saturated. Option C is irrelevant; batch processing is not in use.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Switch to a larger GPU such as V100 or A100 to increase per-replica throughput.
Why it's wrong here
GPU is already saturated; a larger GPU would help but option D more directly addresses CPU bottleneck.
✗
Implement request batching in the custom container to improve GPU utilization efficiency.
Why it's wrong here
GPU already saturated; batching may increase throughput but not reduce errors.
✗
Enable model parallelism across multiple GPUs within each replica.
Why it's wrong here
Model is small; parallelism adds overhead.
✓
Use a high-memory machine type like n1-highmem-16 to reduce memory pressure.
Why this is correct
High-memory machines address memory bottlenecks; memory is likely the real issue given GPU saturation.
Related concept
Authentication checks who the user is.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
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. Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access. 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
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related PMLE questions on access control and AAA configuration.
Serving and scaling models — This question tests Serving and scaling models — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Use a high-memory machine type like n1-highmem-16 to reduce memory pressure. — Option D is correct because CPU bottlenecks cause high latency; switching to a machine type with more CPU cores (e.g., n1-highcpu-16) reduces CPU contention. Option A adds memory but not CPU. Option B uses more replicas but each already saturated. Option C is irrelevant; batch processing is not in use.
What should I do if I get this PMLE question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related PMLE questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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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.
Question Discussion
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