The answer is to set min_instances to a value greater than 0 and enable CPU always allocated. Setting min_instances keeps a baseline of warm containers ready to handle traffic, while CPU always allocated prevents the CPU from being throttled when the container is idle, ensuring the runtime environment remains fully active and responsive. Together, these two steps directly eliminate the cold start latency that occurs when a new container must be spun up from scratch during a traffic spike. On the Google Professional Cloud Developer exam, this scenario tests your understanding of Cloud Run’s scaling and resource allocation controls, often appearing in a multiple-select question where a common trap is choosing only one option or confusing CPU always allocated with min_instances alone. Remember the memory tip: “Keep the engine idling, not off” — min_instances ensures a warm fleet, and CPU always allocated keeps the engine running so it can rev up instantly.
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. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 company deploys a microservice on Cloud Run and wants to minimize cold starts during traffic spikes. Which two steps should they take? (Select exactly 2.)
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.
CPU always allocated ensures instances are active and ready to serve requests immediately.
B
Use Cloud CDN
Why wrong: Cloud CDN caches static content but does not address cold starts for dynamic requests.
C
Set max_instances to a high value
Why wrong: Increasing max_instances only raises the scaling limit, it does not prevent cold starts.
D
Set concurrency to 1
Why wrong: Setting concurrency to 1 limits the number of concurrent requests per instance, which can increase the number of instances needed and worsen cold starts.
E
Set min_instances to a value greater than 0
Min instances keep a baseline of warm instances ready to handle traffic spikes.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable CPU always allocated
Enabling CPU always allocated (option A) prevents the CPU from being throttled when the container is not handling requests, which reduces cold start latency because the runtime environment remains warm and ready to process incoming traffic immediately. This is particularly effective for minimizing cold starts during traffic spikes because the container's CPU is always active, eliminating the need to spin up resources from a cold state.
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.
✓
Enable CPU always allocated
Why this is correct
CPU always allocated ensures instances are active and ready to serve requests immediately.
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.
✗
Use Cloud CDN
Why it's wrong here
Cloud CDN caches static content but does not address cold starts for dynamic requests.
✗
Set max_instances to a high value
Why it's wrong here
Increasing max_instances only raises the scaling limit, it does not prevent cold starts.
✗
Set concurrency to 1
Why it's wrong here
Setting concurrency to 1 limits the number of concurrent requests per instance, which can increase the number of instances needed and worsen cold starts.
✓
Set min_instances to a value greater than 0
Why this is correct
Min instances keep a baseline of warm instances ready to handle traffic spikes.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between scaling limits (max_instances) and proactive instance provisioning (min_instances), so the trap here is that candidates mistakenly think setting a high max_instances prevents cold starts, when in fact it only caps the maximum scale and does nothing to keep instances warm.
Detailed technical explanation
How to think about this question
Under the hood, Cloud Run uses a request-driven autoscaling model where instances are scaled down to zero when idle; setting min_instances to a value greater than 0 (option E) pre-warms a baseline number of instances, ensuring they are always ready to serve requests without the startup delay. When CPU is always allocated (option A), the container's CPU is not throttled during idle periods, which means the runtime environment (e.g., JVM, Node.js event loop) stays warm and can handle requests immediately, reducing the cold start penalty from near-zero to milliseconds. In real-world scenarios, combining min_instances with CPU always allocated is a common pattern for latency-sensitive applications like API gateways or real-time services that must handle sudden traffic spikes without degradation.
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: Enable CPU always allocated — Enabling CPU always allocated (option A) prevents the CPU from being throttled when the container is not handling requests, which reduces cold start latency because the runtime environment remains warm and ready to process incoming traffic immediately. This is particularly effective for minimizing cold starts during traffic spikes because the container's CPU is always active, eliminating the need to spin up resources from a cold state.
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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