Google PCA Ensure solution and operations reliability Practice Question
This PCA practice question tests your understanding of ensure solution and operations reliability. 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.
Company B uses Cloud Endpoints to expose their API. Recently, they started seeing 503 errors during periods of high traffic. They have enabled Cloud Endpoints with a moderate quota. The backend is running on Cloud Run. The Cloud Run service is configured with min instances = 0 and max instances = 100. The container concurrency is set to 80. The average request latency is 200ms. What is the most likely cause and what should they do?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cloud Run is scaling too slowly; set min instances to a higher value.
The 503 errors during high traffic are most likely caused by Cloud Run's scaling latency. With min instances = 0, new requests must wait for a container to start (cold start), and during traffic spikes, the scaling algorithm may not provision instances quickly enough, leading to request timeouts and 503s. Setting a higher min instances value ensures a warm pool of containers is always ready to handle traffic bursts, reducing cold start delays.
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.
✗
The container concurrency is too low; increase it to 200.
Why it's wrong here
Concurrency affects throughput but not cold starts.
✗
The backend is experiencing cold starts; set a higher CPU limit.
Why it's wrong here
CPU limit does not eliminate cold starts.
✓
Cloud Run is scaling too slowly; set min instances to a higher value.
Why this is correct
Cold starts cause latency spikes leading to 503s; warm instances mitigate this.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Cloud Endpoints quota is being exhausted; increase the quota.
Why it's wrong here
Quota exhaustion would cause errors regardless of traffic bursts.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 503 errors with quota exhaustion (option D) or misattribute the issue to concurrency limits (option A), when in fact the 503 is a classic symptom of Cloud Run's cold start and scaling delay with min instances = 0.
Detailed technical explanation
How to think about this question
Cloud Run's autoscaler uses the number of concurrent requests and CPU utilization to decide when to add instances, but it has a built-in cooldown period (default ~30 seconds) before scaling up. During a sudden traffic spike, this delay can cause requests to queue and eventually time out, resulting in 503 errors. Setting min instances to a non-zero value (e.g., 5-10) pre-warms containers, eliminating cold start latency and allowing the autoscaler to handle bursts more smoothly.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PCA question in full detail.
Ensure solution and operations reliability — This question tests Ensure solution and operations reliability — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cloud Run is scaling too slowly; set min instances to a higher value. — The 503 errors during high traffic are most likely caused by Cloud Run's scaling latency. With min instances = 0, new requests must wait for a container to start (cold start), and during traffic spikes, the scaling algorithm may not provision instances quickly enough, leading to request timeouts and 503s. Setting a higher min instances value ensures a warm pool of containers is always ready to handle traffic bursts, reducing cold start delays.
What should I do if I get this PCA 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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