This PCD practice question tests your understanding of deploying applications. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You deployed a microservice on Cloud Run. Users report intermittent 503 errors. The service uses Cloud SQL with connection pooling. What is the most likely cause?
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
✓
The connection pool is drained due to CPU throttling on Cloud Run.
When Cloud Run CPU throttling occurs (e.g., during cold starts or when the instance is processing requests beyond its allocated CPU), the connection pool can become drained because existing connections are held open while new requests cannot be processed. This leads to intermittent 503 errors as the service cannot establish new database connections or respond to incoming requests in time. Connection pooling does not protect against CPU throttling; it only manages database connections efficiently.
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 service is not using a VPC connector for Cloud SQL access.
Why it's wrong here
VPC connector is needed for private IP, but public IP works without it.
✓
The connection pool is drained due to CPU throttling on Cloud Run.
Why this is correct
When no requests, CPU is throttled, causing idle connections to be dropped by the database.
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 SQL auth proxy is not configured.
Why it's wrong here
Cloud Run automatically sets up the Cloud SQL auth proxy when using private IP.
✗
The Cloud Run service name is not resolvable via Cloud DNS.
Why it's wrong here
Cloud Run services have a stable URL; DNS is not an issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that 503 errors from Cloud Run are always due to database connectivity issues (like missing auth proxy or VPC), when in fact CPU throttling and connection pool exhaustion are the primary causes in serverless environments.
Detailed technical explanation
How to think about this question
Cloud Run CPU throttling occurs when the container's CPU usage exceeds the allocated limit, causing requests to be queued or dropped. The connection pool (e.g., HikariCP) maintains a fixed number of database connections; if CPU is throttled, the application cannot process requests to return connections to the pool, leading to pool exhaustion. This is distinct from database connection limits—Cloud SQL's max connections (e.g., 100 for db-f1-micro) can also be a factor, but CPU throttling is the more common cause on Cloud Run due to its autoscaling and concurrency model.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Deploying applications — This question tests Deploying applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The connection pool is drained due to CPU throttling on Cloud Run. — When Cloud Run CPU throttling occurs (e.g., during cold starts or when the instance is processing requests beyond its allocated CPU), the connection pool can become drained because existing connections are held open while new requests cannot be processed. This leads to intermittent 503 errors as the service cannot establish new database connections or respond to incoming requests in time. Connection pooling does not protect against CPU throttling; it only manages database connections efficiently.
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: "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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PCD practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCD exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.