Google PCA Practice Question: Analyze and optimize technical and business processes
A company is running a web application on Compute Engine instances that average 20% CPU utilization. They want to reduce costs without impacting performance. What is the most effective action?
⚠ Common exam trap
Candidates often choose committed use discounts (Option C) as a quick cost-saving measure, failing to realize that rightsizing first yields greater savings without long-term commitment, and that preemptible instances (Option D) are not viable for production traffic due to their ephemeral nature.
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
✓
Rightsize instances to a smaller machine type based on usage metrics.
The instances are averaging only 20% CPU utilization, indicating they are over-provisioned. Rightsizing to a smaller machine type directly reduces the compute cost per instance while maintaining adequate performance for the current workload, as the smaller instance can handle the existing load without degradation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Rightsize instances to a smaller machine type based on usage metrics.
Why this is correct
Rightsizing selects a smaller machine type whose vCPU and memory match the observed 20% utilisation, so the workload runs on cheaper instances without performance loss. This directly removes the cost of over-provisioned capacity identified by the usage metrics.
- ✗
Change instance type to e2-standard-4.
Why it's wrong here
An e2-standard-4 provides four vCPUs, increasing capacity rather than reducing it, so cost rises while 20% utilisation persists. It is tempting because resizing is the standard remedy for resource-starved instances, which would be correct if CPU or memory were saturated and performance were degraded.
- ✗
Purchase 3-year committed use discounts.
Why it's wrong here
Committed use discounts cut the price of the vCPUs and memory you already run, but they do not address the 20% utilisation, so you still pay for idle capacity. They are tempting because they reliably lower steady-state compute bills, which would be correct for predictable, long-running workloads already right-sized.
- ✗
Use preemptible instances for all traffic.
Why it's wrong here
Preemptible instances are reclaimed within 24 hours and cannot serve all production traffic reliably, so performance and availability would suffer. They are tempting because they cost far less than standard instances, which would be correct for interruptible batch processing or fault-tolerant workloads that tolerate sudden termination.
Go deeper
Related to this question
Learn chapter
Load Balancing and Autoscaling
Key term
Machine type
A machine type defines the virtual hardware resources (vCPU, memory, and sometimes GPU) assigned to a virtual machine instance in a cloud computing environment.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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Written by Johnson Ajibi, MSc IT Security
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