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Google ACE Practice Question: An e-commerce platform sees a 20x traffic spike…

An e-commerce platform sees a 20x traffic spike every Black Friday. The rest of the year traffic is low and stable. The team wants to minimize costs during normal periods while handling the annual peak without manual intervention. Which architecture achieves this?

⚠ Common exam trap

Google Cloud often tests the misconception that database services like Cloud SQL can automatically scale compute for traffic spikes, but in reality, Cloud SQL requires manual vertical scaling or read replicas and does not handle web-tier traffic spikes natively.

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

Managed instance group with autoscaling + scheduled scaling pre-warming before Black Friday

It combines managed instance group autoscaling for normal low-cost operation with scheduled scaling to pre-warm capacity before the Black Friday spike, ensuring seamless handling of the 20x traffic surge without manual intervention. This approach uses the 'autoscaler' and 'scheduled scaling' features in Google Cloud to dynamically adjust resources based on load, while pre-warming prevents cold-start latency during the peak.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Pre-provision 20x capacity year-round to guarantee Black Friday performance

    Why it's wrong here

    Pre-provisioning 20x capacity year-round means paying for 20 times the required number of instances for 364 days when the extra capacity is completely idle, resulting in severe cost waste and unnecessary operational overhead. You would also need to patch, monitor, and manage these idle instances continuously, and underutilized resources can still incur sustained-use or per-second billing charges. Autoscaling with a scheduled policy provides the same surge capacity on Black Friday without the ongoing cost penalty, making this option cost-prohibitive and technically inefficient.

  • Managed instance group with autoscaling + scheduled scaling pre-warming before Black Friday

    Why this is correct

    A managed instance group (MIG) with autoscaling can scale out based on real-time load metrics such as CPU utilization or requests per second, automatically adding instances as demand rises. Adding a scheduled scaling policy that pre-warms capacity a few hours before Black Friday ensures the additional instances are fully initialized, warmed up, and ready to accept traffic before the spike hits, avoiding the latency and slow startup that could occur if scaling were purely reactive. Together these provide both proactive capacity for the expected surge and reactive scaling for any unexpected above-forecast demand, making this the correct solution.

  • Deploy on Cloud SQL — it scales compute automatically for traffic spikes

    Why it's wrong here

    Cloud SQL is a fully managed relational database service, not a compute platform for serving web traffic. While Cloud SQL can scale storage automatically and supports read replicas for read-heavy workloads, it does not scale compute (vCPU/RAM) in response to Web traffic spikes, and it is not designed to host application servers or frontend web tiers. The problem requires scaling compute instances for an application layer, so choosing Cloud SQL would leave the web-serving capacity untouched and also incorrectly conflate database scaling with application-tier scaling.

  • Add 20 manual VMs on Black Friday and delete them afterward each year

    Why it's wrong here

    Manually adding VMs on Black Friday requires an engineer to constantly monitor traffic forecasts and provision resources at just the right moment, which is error-prone and could be delayed by human reaction time. The instances also need to be manually deleted after the sale, creating cleanup overhead and risk of leaving resources running. Google Cloud's managed instance groups with scheduled autoscaling policies can automatically pre-warm capacity on a recurring annual schedule, eliminating the need for any hands-on intervention while still handling the traffic spike reliably.

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Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

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