PCDOE Optimizing performance and cost — 20 Questions

Question 1

A company is using Google Kubernetes Engine (GKE) with multiple node pools. They notice that their monthly costs are higher than expected. Upon review, they find that several preemptible VMs are being recreated frequently, leading to sustained usage costs. What is the most cost-effective solution to reduce costs?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Migrate to Spot VMs, which have a lower price and no maximum runtime.. Spot VMs are the recommended replacement for preemptible VMs, offering the same low price but without the 24-hour maximum runtime limit. This eliminates the frequent recreation and sustained usage costs caused by preemptible VMs being terminated and restarted, directly reducing monthly expenses.

Answer

Purchase committed use discounts for the preemptible VMs.

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Increase the number of preemptible VMs to spread the workload.

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Enable sustained use discounts for the existing VMs.

Question 2

A company runs a batch processing workload on Compute Engine that runs for 3 hours every night. They want to minimize costs while ensuring the job completes reliably. Which recommendation should they follow?

Accepted Answer

Use preemptible VMs and design the job to handle interruptions gracefully.. Preemptible VMs cost about 60-80% less than standard VMs and are ideal for batch workloads that can tolerate interruptions. Since the job runs for only 3 hours nightly, it can be designed to checkpoint progress and restart from the last checkpoint if a preemptible VM is terminated (which can happen at any time within 24 hours). This minimizes cost while ensuring reliability through graceful interruption handling.

Answer

Use sole-tenant nodes to isolate the workload.

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Use standard (on-demand) VMs and enable sustained use discounts.

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Purchase 1-year committed use discounts for the VMs.

Question 3

A company uses Cloud CDN to deliver content globally. They notice increasing egress costs. Which change will most effectively reduce egress costs?

Accepted Answer

Configure Cloud CDN to cache more content and increase cache hit ratio.. Increasing the cache hit ratio reduces the number of requests that reach the origin server, which directly lowers the volume of data transferred from the origin to the CDN edge. Since egress costs are primarily driven by data served from the CDN edges to users, caching more content at the edge minimizes the need to fetch and serve data from the origin, thereby reducing overall egress traffic and associated costs.

Answer

Switch to a premium tier network for lower egress rates.

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Enable gzip compression for all responses.

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Use Cloud Armor to block malicious traffic.

Question 4

A company is using Google Cloud and wants to monitor and control costs. Which TWO actions should they take? (Choose two.)

Accepted Answer

Set up budget alerts to notify when spending exceeds thresholds.. Setting up budget alerts (option A) is a core cost control action because it allows you to define a budget amount and receive notifications when actual or forecasted spending exceeds a specified threshold (e.g., 50%, 90%, 100%). This enables proactive intervention before costs spiral out of control. Using labels (option B) to categorize resources (e.g., by team, project, or environment) allows you to track and allocate costs accurately in billing reports, making it easier to identify cost drivers and enforce accountability.

Answer

Disable all unnecessary APIs at the organization level.

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Export billing data to BigQuery for detailed analysis.

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Grant billing account access to all project owners.

Question 5

You are a DevOps engineer at a large e-commerce company that runs its production workloads on Google Kubernetes Engine (GKE) in the us-central1 region. The cluster has 500 nodes, each with 8 vCPUs and 32 GB of memory, and uses preemptible VMs for cost savings. Over the past month, the monthly GKE cost has increased by 30% unexpectedly. Upon reviewing the billing reports, you notice a significant spike in Compute Engine costs, specifically for 'Sustained Use Discount' line items, but the total cost is higher than expected. You also observe that the cluster's node utilization is inconsistent, with some nodes running at 90% CPU and memory while others are below 20%. Your team has been deploying stateless microservices and using Cluster Autoscaler with default settings. The application traffic is variable but predictable, with peaks on weekends. You need to reduce the GKE costs without impacting performance. What should you do?

Accepted Answer

Enable node auto-provisioning and migrate baseline workloads to nodes covered by committed use discounts (1-year or 3-year).. Enabling node auto-provisioning allows GKE to automatically select the most cost-effective node configurations for your workloads, reducing waste from over-provisioned nodes. Migrating baseline workloads to nodes covered by committed use discounts (CUDs) locks in lower prices for predictable usage, directly addressing the 30% cost spike caused by inconsistent utilization and unexpected sustained use discount charges. This combination optimizes both variable and steady-state workloads without sacrificing performance.

Answer

Increase the minimum number of nodes in the cluster to 300 and use a larger machine type to reduce the number of pods per node.

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Switch the cluster to a single-zone configuration and reduce the number of nodes to 200 to lower base costs.

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Reduce the number of preemptible VMs to 30% and use only on-demand VMs for the remaining nodes to improve reliability.

Question 6

A company runs a critical application on Google Kubernetes Engine (GKE) with 3 nodes (e2-standard-4). To reduce costs, the team is considering right-sizing the nodes. The application is latency-sensitive and experiences periodic traffic spikes. What is the most cost-effective approach that maintains performance during spikes?

Accepted Answer

Create a node pool with smaller nodes (e2-standard-2) using preemptible VMs and enable cluster autoscaler.. The most cost-effective approach because it uses smaller e2-standard-2 nodes with preemptible VMs, which are significantly cheaper than regular VMs, and combines this with the cluster autoscaler to automatically add nodes during traffic spikes. This ensures that the latency-sensitive application maintains performance by scaling out horizontally when needed, while minimizing baseline costs with smaller, cheaper nodes.

Answer

Use a single larger node (n2-standard-8) to reduce node count and network overhead.

Answer

Switch to 3 n2-standard-2 nodes to reduce vCPU and memory, and rely on horizontal pod autoscaling.

Answer

Keep current node size but use committed use discounts for 1 year to reduce per-hour cost.

Question 7

Arrange the steps to troubleshoot a high latency issue on a Google Cloud HTTP(S) Load Balancer.

Accepted Answer

Check health checks, then review load balancer logs, then analyze metrics, then identify the problematic backend, then take corrective action.. Start with health checks, then logs, metrics, identify culprit, and take action.

Answer

Analyze metrics, then review logs, then check health checks, then identify the problematic backend, then take corrective action.

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Check health checks, then identify the problematic backend from logs, then take corrective action, then analyze metrics, then verify.

Answer

Review logs, then analyze metrics, then identify the problematic backend, then take corrective action.

Question 8

Order the steps to respond to a Google Cloud security incident involving a compromised service account key.

Accepted Answer

Revoke key, then rotate key, then audit logs, then assess impact, then update policies.. The correct order for responding to a compromised service account key is: first revoke the key to stop unauthorized use, then rotate (reissue) a new key to restore legitimate access, then audit logs to understand the scope, then assess the impact on resources, and finally update security policies to prevent future incidents. This sequence balances containment, recovery, investigation, and improvement.

Answer

Audit logs, then revoke key, then rotate key, then assess impact, then update policies.

Answer

Rotate key, then revoke key, then audit logs, then assess impact, then update policies.

Answer

Revoke key, then audit logs, then rotate key, then assess impact, then update policies.

Question 9

Match each cost optimization practice to its description.

Accepted Answer

Committed Use Discounts: Discounts for committing to use a certain amount of resources for 1 or 3 years.. Common cost management techniques on Google Cloud include Committed Use Discounts (long-term commitment savings), Preemptible VMs (short-lived cheaper instances), Sustained Use Discounts (automatic monthly usage discounts), and Custom Machine Types (tailored VMs). The distractors swap definitions between related practices.

Answer

Committed Use Discounts: Short-lived, lower-cost instances that can be terminated at any time.

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Preemptible VMs: Discounts for committing to use a certain amount of resources for 1 or 3 years.

Question 10

A company uses BigQuery for analytics with many queries scanning terabytes daily. They need to reduce query costs without reducing usage. What is the most effective strategy?

Accepted Answer

Partition and cluster tables.. Partitioning and clustering BigQuery tables reduces the amount of data scanned per query by limiting partitions and using clustered columns for filtering, directly lowering on-demand query costs. This is the most effective cost-reduction strategy without reducing query volume.

Answer

Reserve capacity in specific regions.

Answer

Use flat-rate pricing with slots.

Answer

Use standard SQL instead of legacy SQL.

Question 11

A company has multiple projects under an organization. They want to allocate costs to different departments based on project labels. They have applied labels to all resources, but the cost reports show 'Unlabeled' for many resources. What is the most likely cause?

Accepted Answer

Labels were applied after the billing period.. Cost allocation labels in cloud billing are applied at the time resources are created or updated, and billing exports capture the label state as of the billing period. If labels were applied after the billing period closed, the historical cost records for that period will not reflect them, causing those resources to appear as 'Unlabeled' in cost reports. This is the most likely cause when labels exist on resources but reports still show unlabeled costs.

Answer

Labels are not propagated to billing export.

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The billing export is not configured.

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The project uses a different billing account.

Question 12

A company wants to control costs by limiting the maximum number of Compute Engine instances a project can create. Which TWO methods can achieve this? (Choose two.)

Accepted Answer

Set resource quotas for compute instances.. Resource quotas are the only method among the options that can limit the maximum number of instances by setting a hard cap on instance count. IAM conditions can restrict instance creation based on attributes like machine type or region but cannot enforce a numeric limit on the number of instances. Therefore, only option D is correct.

Answer

Use IAM conditions to restrict instance creation.

Answer

Enable preemptible VMs.

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Create budget alerts with a threshold at 80% of budget.

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Apply committed use discounts.

Question 13

Refer to the exhibit. A DevOps engineer wants to reduce compute costs immediately. Which action is most effective?

Accepted Answer

Rightsize instance-2 from n1-standard-8 to n1-standard-4.. Rightsizing instance-2 from n1-standard-8 to n1-standard-4 directly reduces the number of vCPUs and memory allocated, which lowers the hourly compute cost. Since the instance is running, this change takes effect after a stop/start and immediately reduces the billing rate. This is the most effective immediate cost-saving action among the options because it addresses over-provisioning without affecting availability or requiring architectural changes.

Answer

Delete the terminated instance.

Answer

Change instance-1 to a non-preemptible instance.

Answer

Move instance-1 to a different zone.

Question 14

Refer to the exhibit. The company received an alert when the threshold was triggered. What does this alert indicate?

Accepted Answer

The actual spend has reached 50% of the budget.. The alert indicates that the actual spend has reached 50% of the budget. This is a threshold alert, typically set to notify when spending hits a certain percentage of the budget. The exhibit likely shows a budget with a 50% threshold, and the alert was triggered because actual spend met that threshold.

Answer

The spend has exceeded the budget amount.

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The forecasted spend is projected to exceed 50% of the budget.

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Both actual and forecasted spend thresholds have been crossed.

Question 15

A company has multiple projects in an organization. They want to set a budget of $5000 per month on a specific project and receive notifications when spending reaches 50% and 90%. What should they do?

Accepted Answer

Create a budget at the project level with alert thresholds of 50% and 90%. Google Cloud budgets are scoped to a specific billing account and can be filtered to a single project, so creating a budget at the project level with alert thresholds of 50% and 90% directly meets the requirement of a $5000 monthly budget on that project with notifications at those percentages. Budget alerts are configured as percentages of the budget amount, and Cloud Billing automatically sends email notifications to Billing Account Administrators and Billing Account Users when each threshold is crossed. This is the native, no-code solution designed for exactly this use case.

Answer

Use the Cloud Billing API to monitor spending and send custom alerts

Answer

Create a budget at the organization level with alert thresholds of 50% and 90%

Answer

Configure a Pub/Sub topic and set up a cloud function to check spending daily

Question 16

A large enterprise manages costs across multiple GCP projects using a shared billing account. They want to apply a 10% discount on all committed use discounts (CUDs) to specific departments based on resource labels. How should they allocate the CUD savings?

Accepted Answer

Enable 'CUD cost attribution' in the billing account settings to automatically distribute savings based on project labels. Google Cloud's CUD cost attribution feature, enabled at the billing account level, automatically distributes committed use discount savings across projects and resources based on their usage and labels. This allows enterprises to allocate CUD savings to specific departments without manual calculation, using the same label-based attribution that governs the underlying resource usage.

Answer

Use the Cloud Billing report's 'Cost Attribution' feature to assign CUD savings based on labels

Answer

Use the Cloud Billing cost table in BigQuery with the CUD cost data and allocate using custom queries

Answer

Manually calculate CUD savings and distribute via journal entries

Question 17

Refer to the exhibit. A DevOps engineer noticed that the nightly batch processing costs are higher than expected. After running the above command, what is the most likely cause?

Accepted Answer

The instances are not preemptible, leading to higher compute costs. The command likely lists instances and shows that they are not preemptible, meaning they are standard instances that cost more. Preemptible VMs are significantly cheaper, so if the batch processing uses non-preemptible instances, costs will be higher than expected.

Answer

The instances are running in different zones, increasing egress costs

Answer

The instances are using the n2-standard-4 machine type, which is expensive

Answer

The instances have automatic restart enabled, incurring additional charges

Question 18

Refer to the exhibit. A DevOps engineer configured a budget alert with Pub/Sub notifications. However, the team is not receiving alerts. The Pub/Sub subscription is set up correctly and messages can be published manually. What is the most likely reason the budget alerts are not being sent?

Accepted Answer

The budget filter excludes credits, so actual spend might be lower than threshold. The budget filter excludes credits, so actual spend might be lower than the threshold is correct because Cloud Billing budget alerts evaluate the spend amount after applying the budget's filters. If the filter excludes credits, the measured spend used for threshold comparison is reduced by credit amounts, so the effective spend may never cross the configured threshold even though gross usage is high. The Pub/Sub subscription and notification rule can be perfectly configured, yet no alert fires because the threshold condition is never met.

Answer

The notificationsRule does not include email recipients

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The budget amount is specified in units without considering fractional cents

Answer

The threshold rules use different spend basis (CURRENT vs FORECASTED), causing inconsistency

Question 19

Refer to the exhibit. A DevOps engineer needs to view the cost report for a project. Which role should be granted at the organization level to allow viewing billing data for all projects in the organization?

Accepted Answer

roles/billing.viewer. The `roles/billing.viewer` role grants read-only access to billing data, including cost reports, budgets, and billing account information, at the level it is bound (organization, folder, or project). Binding it at the organization level allows the DevOps engineer to view cost reports for all projects within the organization without granting the ability to modify billing settings. This satisfies the least-privilege requirement of viewing billing data across all projects.

Answer

roles/billing.admin

Answer

roles/billing.creator

Answer

roles/billing.user

Question 20

A company has purchased Compute Engine committed use discounts (CUD) for 1 year for vCPU and memory. After 3 months, they need to upgrade some VMs to a larger machine type. What happens to the CUD coverage?

Accepted Answer

The CUD continues to apply to the original resource, and any additional usage is charged at on-demand rates. Committed Use Discounts (CUDs) apply to resource usage (vCPU, memory) rather than specific machine types. When upgrading to a larger machine type, the original committed resources are still used; any additional usage beyond the committed amount is charged at on-demand rates. Option A is incorrect because CUDs are not automatically adjusted. Option C is incorrect because CUDs do cover upgrades as long as the resource types match. Option D is incorrect because CUDs are not voided or refunded.

Answer

The CUD is automatically adjusted to cover the new machine type

Answer

The CUD applies only to the specific machine types in the commitment, so upgrades are not covered

Answer

The CUD is voided and a refund is issued