Google PCA Manage and provision cloud infrastructure Practice Question
This PCA practice question tests your understanding of manage and provision cloud infrastructure. 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.
A Cloud Run service frequently fails with 502 errors when making requests to a backend service running on Compute Engine. The two services are in the same VPC network. The Cloud Run service is configured with a VPC connector. 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 VPC connector is not attached to the correct subnet, or the firewall rules are blocking traffic from the connector's IP range.
Option C is correct because Cloud Run uses a VPC connector to send requests to resources in a VPC. If the connector is attached to the wrong subnet, its egress traffic may not reach the Compute Engine instance, or firewall rules may block traffic from the connector's IP range (e.g., 10.8.0.0/28). This results in 502 errors from the backend, as the Cloud Run service cannot establish a TCP connection to the Compute Engine instance.
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 Cloud Run service needs to be peered with the VPC using VPC Network Peering.
Why it's wrong here
Cloud Run uses a VPC connector, not peering.
✗
The VPC connector is set to a low number of instances, causing traffic throttling.
Why it's wrong here
Throttling would cause timeouts, not 502 errors specifically.
✓
The VPC connector is not attached to the correct subnet, or the firewall rules are blocking traffic from the connector's IP range.
Why this is correct
The VPC connector's subnet must have routes to the backend, and firewall rules must allow ingress from the connector's IP range.
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 Run service's service account lacks the roles/compute.instanceAdmin role.
Why it's wrong here
No such role is required for outbound traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse VPC Network Peering (used for inter-VPC connectivity) with the VPC connector (used for serverless-to-VPC access), and they overlook the firewall rules that must explicitly allow traffic from the connector's IP range.
Detailed technical explanation
How to think about this question
The VPC connector creates a custom subnet (e.g., 10.8.0.0/28) in the VPC and uses Cloud NEGs (Network Endpoint Groups) to route traffic. Firewall rules must allow ingress from this subnet to the Compute Engine instance's target port (e.g., TCP 8080). If the connector's subnet is in a different region or the firewall has an implicit deny, the TCP SYN packet is dropped, causing a 502 Bad Gateway from Cloud Run's side. Real-world scenarios often involve misconfigured firewall rules that allow HTTP but not HTTPS, or vice versa.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PCA question in full detail.
Manage and provision cloud infrastructure — This question tests Manage and provision cloud infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The VPC connector is not attached to the correct subnet, or the firewall rules are blocking traffic from the connector's IP range. — Option C is correct because Cloud Run uses a VPC connector to send requests to resources in a VPC. If the connector is attached to the wrong subnet, its egress traffic may not reach the Compute Engine instance, or firewall rules may block traffic from the connector's IP range (e.g., 10.8.0.0/28). This results in 502 errors from the backend, as the Cloud Run service cannot establish a TCP connection to the Compute Engine instance.
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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