The correct configuration is to set min-instances to a non-zero value and enable CPU always-on. Setting min-instances to a non-zero value keeps a baseline of warm instances ready, which directly eliminates cold start latency for predictable traffic, while enabling CPU always-on prevents the instance’s CPU from being throttled to zero during idle periods, ensuring the instance can immediately process incoming requests without a cold start penalty. On the Google Professional Cloud Developer exam, this scenario tests your understanding of how Cloud Run’s scaling and CPU throttling interact under unpredictable traffic; a common trap is assuming that simply increasing max-instances or using concurrency settings alone will solve cold starts, but without warm instances and active CPU, spikes still cause request drops. Remember the memory tip: “Warm and awake” — min-instances keeps the instance warm, CPU always-on keeps it awake, so your app never sleeps through a spike.
PCD Practice Question: Designing highly scalable, available, and reliable cloud-native applications
This PCD practice question tests your understanding of designing highly scalable, available, and reliable cloud-native applications. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A development team is deploying a new application on Cloud Run. They anticipate unpredictable traffic patterns and want to minimize cold start latency. They also need to ensure that the application can handle sudden spikes without request drops. Which configuration should they use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set min-instances to a non-zero value to keep some instances warm, and enable CPU always-on.
Setting min-instances to a non-zero value ensures that Cloud Run always keeps at least that many instances warm, eliminating cold starts for baseline traffic. Enabling CPU always-on prevents the instance's CPU from being throttled to zero when idle, allowing the instance to handle incoming requests immediately without a cold start penalty. This combination minimizes latency for unpredictable traffic and ensures capacity to absorb sudden spikes without dropping requests.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use App Engine Standard Environment with automatic scaling.
Why it's wrong here
App Engine Standard is serverless with warmup requests, but Cloud Run offers more flexibility.
✓
Set min-instances to a non-zero value to keep some instances warm, and enable CPU always-on.
Why this is correct
Min-instances keeps containers warm; CPU always-on prevents cold start latency.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set min-instances to 0 and max-instances to a high number to allow scaling from zero.
Why it's wrong here
Scaling from zero causes cold starts.
✗
Use Cloud Functions instead of Cloud Run for better cold start performance.
Why it's wrong here
Cloud Functions also has cold starts and may have longer execution timeouts.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that setting min-instances to 0 is acceptable for minimizing cold starts, or that switching to a different serverless product like Cloud Functions inherently solves cold start issues, when in fact the correct approach is to keep instances warm with min-instances and CPU always-on.
Detailed technical explanation
How to think about this question
Cloud Run's min-instances feature works by pre-provisioning and keeping the specified number of container instances always running, even when there is no traffic. CPU always-on (enabled via the `--cpu-boost` or `--no-cpu-throttling` flag) prevents the CPU from being throttled to near zero during idle periods, which means the instance can serve requests immediately without needing to 'warm up' the runtime or re-establish database connections. In practice, for applications with unpredictable spikes, setting min-instances to 1 or 2 (depending on expected baseline) and enabling CPU always-on can reduce p99 latency by 50-80% compared to scaling from zero.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Designing highly scalable, available, and reliable cloud-native applications — This question tests Designing highly scalable, available, and reliable cloud-native applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set min-instances to a non-zero value to keep some instances warm, and enable CPU always-on. — Setting min-instances to a non-zero value ensures that Cloud Run always keeps at least that many instances warm, eliminating cold starts for baseline traffic. Enabling CPU always-on prevents the instance's CPU from being throttled to zero when idle, allowing the instance to handle incoming requests immediately without a cold start penalty. This combination minimizes latency for unpredictable traffic and ensures capacity to absorb sudden spikes without dropping requests.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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