- A
The Cloud SQL Proxy container is using an outdated version that is incompatible with the current Cloud SQL API.
Why wrong: Proxy versions are backward-compatible; an outdated version would still connect, though features may be missing.
- B
The application is using a wrong database password in the connection string.
Why wrong: Wrong password would cause authentication failures, not connection timeouts; the proxy connection would succeed.
- C
The pod's namespace does not have the Cloud SQL Proxy configuration correctly set up.
Why wrong: The proxy command is in the pod spec, not namespace-level config; namespace doesn't affect proxy connectivity.
- D
The Cloud SQL instance is configured with a private IP and the GKE cluster is VPC-native but the Cloud SQL Proxy is configured to connect via public IP.
The proxy defaults to public IP; with a private IP instance and no public IP, connection times out.
Quick Answer
The answer is that the Cloud SQL Proxy is configured to connect via public IP while the Cloud SQL instance uses a private IP, causing the timeout. This is correct because the proxy command `/cloud_sql_proxy -instances=<instance-connection-name>=tcp:5432` defaults to a public IP connection, but when the Cloud SQL instance is configured with a private IP and the GKE cluster is VPC-native, the proxy must include the `-private-ip` flag to route traffic over the internal VPC. Without this flag, the proxy attempts to reach the instance’s public endpoint, which fails because the authorized networks only cover the nodes’ public IP range, not the pod’s private subnet—a mismatch often exposed after a cluster upgrade changes node networking. On the Google Professional Cloud Developer exam, this scenario tests your understanding of Cloud SQL Proxy flags and VPC-native cluster connectivity, a common trap where candidates overlook the `-private-ip` flag when both resources reside in the same region. Memory tip: “Private IP needs the private flag”—always append `-private-ip` when your Cloud SQL instance lacks a public IP.
PCD Building and testing applications Practice Question
This PCD practice question tests your understanding of building and testing 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.
A company runs a web application on Google Kubernetes Engine (GKE) that uses Cloud SQL for its database. The application is deployed via Cloud Build and uses a custom container image stored in Artifact Registry. Recently, the development team noticed that new deployments are failing with a 'CrashLoopBackOff' error in the pod logs. The logs indicate that the application cannot connect to the Cloud SQL instance. The application uses the Cloud SQL Proxy sidecar container to connect. The Cloud SQL Proxy configuration has not changed recently. The GKE cluster is in region us-central1, and the Cloud SQL instance is in us-central1 as well. The team verified that the Cloud SQL instance is running and accepting connections from authorized networks. They also confirmed that the service account used by the pod has the 'Cloud SQL Client' role. The application has been running stable for months until a recent GKE cluster upgrade. The deployment YAML uses environment variables for database connection. The Cloud SQL Proxy is deployed as a sidecar container with command: '/cloud_sql_proxy -instances=<instance-connection-name>=tcp:5432'. The pod logs show the proxy attempting to connect but timing out. The network team confirms that there are no firewall rules blocking the connection. The Cloud SQL instance has an authorized network entry for the GKE cluster's nodes' IP range. What is the most likely cause of the connection failure?
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 choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The Cloud SQL instance is configured with a private IP and the GKE cluster is VPC-native but the Cloud SQL Proxy is configured to connect via public IP.
Option D is correct because the Cloud SQL Proxy sidecar is configured to connect via public IP (using the instance connection name without the `-private-ip` flag), but the Cloud SQL instance is configured with a private IP. Since the GKE cluster is VPC-native, the pod can reach the private IP within the VPC, but the proxy is attempting a public IP connection, which fails because the instance's authorized networks only include the GKE nodes' IP range (public IPs of nodes), not the pod's private IP range. The recent GKE cluster upgrade may have changed the node's public IP or networking configuration, exacerbating the mismatch.
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 SQL Proxy container is using an outdated version that is incompatible with the current Cloud SQL API.
Why it's wrong here
Proxy versions are backward-compatible; an outdated version would still connect, though features may be missing.
- ✗
The application is using a wrong database password in the connection string.
Why it's wrong here
Wrong password would cause authentication failures, not connection timeouts; the proxy connection would succeed.
- ✗
The pod's namespace does not have the Cloud SQL Proxy configuration correctly set up.
Why it's wrong here
The proxy command is in the pod spec, not namespace-level config; namespace doesn't affect proxy connectivity.
- ✓
The Cloud SQL instance is configured with a private IP and the GKE cluster is VPC-native but the Cloud SQL Proxy is configured to connect via public IP.
Why this is correct
The proxy defaults to public IP; with a private IP instance and no public IP, connection times out.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between public and private IP connectivity for Cloud SQL Proxy, where candidates assume the proxy automatically uses the correct IP based on the instance configuration, but it requires an explicit flag to use private IP.
Trap categories for this question
Command / output trap
The proxy command is in the pod spec, not namespace-level config; namespace doesn't affect proxy connectivity.
Detailed technical explanation
How to think about this question
The Cloud SQL Proxy supports both public and private IP connections via the `-instances` flag; to use private IP, you must append `?private-ip=true` to the instance connection string. In a VPC-native GKE cluster, pods are assigned internal IPs from a secondary range, and the Cloud SQL instance with private IP is accessible only from within the VPC or via VPC peering. The proxy's default behavior is to resolve the instance connection name to a public IP, which fails if the instance has no public IP or if the pod's egress is restricted.
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.
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FAQ
Questions learners often ask
What does this PCD question test?
Building and testing applications — This question tests Building and testing applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Cloud SQL instance is configured with a private IP and the GKE cluster is VPC-native but the Cloud SQL Proxy is configured to connect via public IP. — Option D is correct because the Cloud SQL Proxy sidecar is configured to connect via public IP (using the instance connection name without the `-private-ip` flag), but the Cloud SQL instance is configured with a private IP. Since the GKE cluster is VPC-native, the pod can reach the private IP within the VPC, but the proxy is attempting a public IP connection, which fails because the instance's authorized networks only include the GKE nodes' IP range (public IPs of nodes), not the pod's private IP range. The recent GKE cluster upgrade may have changed the node's public IP or networking configuration, exacerbating the mismatch.
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.
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Last reviewed: Jun 25, 2026
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.
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