Google PCA Practice Question: Managing and Provisioning a Solution Infrastructure
A retail company runs a stateless web tier on a managed instance group (MIG) of Compute Engine VMs behind an external Application Load Balancer. Traffic spikes every evening and the operations team currently resizes the MIG manually. They want the group to add and remove VMs automatically based on CPU utilization without changing the instance template. What should the architect configure?
⚠ Common exam trap
The trap here is assuming that scheduling a resize or using preemptible capacity counts as autoscaling, when only a MIG autoscaling policy reacts automatically to utilization metrics.
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
✓
An autoscaling policy on the managed instance group using a CPU utilization target.
A managed instance group autoscaling policy is the native mechanism for adding and removing Compute Engine VMs in response to load signals such as CPU utilization. Because the web tier is stateless and already behind a load balancer, horizontal scaling is safe and does not require rebuilding the instance template.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A Cloud Scheduler job that calls the Compute Engine API to resize the managed instance group every evening.
Why it's wrong here
A scheduled resize is time-based, not load-based, so it cannot react to unexpected spikes or quiet periods. It also requires custom scripting and credentials, adding operational overhead. The requirement is automatic scaling driven by CPU utilization, which a MIG autoscaling policy provides natively.
- ✗
A network endpoint group (NEG) that automatically registers new VM instances when CPU usage rises.
Why it's wrong here
A network endpoint group defines endpoints for load balancing; it does not create or delete VMs and has no CPU-based scaling logic. NEGs are used to route traffic to endpoints such as GKE pods or serverless backends, so this does not meet the automatic capacity requirement.
- ✗
A preemptible VM pool that the load balancer adds to the backend service during peak hours.
Why it's wrong here
Preemptible VMs can be reclaimed at any time, which would degrade a customer-facing web tier, and a backend service does not itself add capacity. Preemptibility is also an instance property set at creation, so this does not satisfy automatic CPU-driven scaling without template changes.
- ✓
An autoscaling policy on the managed instance group using a CPU utilization target.
Why this is correct
Autoscaling policies on a MIG add or remove instances based on signals such as average CPU utilization across the group. Because the web tier is stateless and already sits behind a load balancer, scaling the MIG horizontally is the intended pattern and requires no changes to the instance template.
Go deeper
Related to this question
Learn chapter
Virtual Machine Instances in Compute Engine
Key term
Compute Engine
Compute Engine is Google Cloud's Infrastructure-as-a-Service (IaaS) offering that lets you create and run virtual machines on Google's infrastructure.
Key term
Managed instance group
A managed instance group is a collection of identical virtual machine instances that are automatically managed as a single unit to ensure high availability and scalability.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
This PCA 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 PCA exam.