- A
The Cloud SQL instance requires SSL connections, and the client is not using SSL.
Why wrong: Incorrect: If SSL were required, the error would be 'SSL required' or 'SSL off', not a timeout.
- B
The Cloud SQL instance does not have a private IP assigned, but the VM is attempting to connect using the private IP.
Correct: The '--assign-ip' flag only assigns a public IP. To use private IP, the instance needs to be configured with a private network. The VM likely uses the private IP because it is in the same region, but the instance doesn't have one.
- C
The VM's firewall is blocking egress to port 5432 on the Cloud SQL public IP.
Why wrong: Incorrect: The exhibit states the firewall allows egress to 0.0.0.0/0 on port 5432.
- D
The authorized networks setting is too permissive; it should be restricted to the VM's public IP.
Why wrong: Incorrect: 0.0.0.0/0 allows all IPs, so it should work. Restricting would not fix the issue.
Google PCA Design and plan a cloud solution architecture Practice Question
This PCA practice question tests your understanding of design and plan a cloud solution architecture. 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.
Refer to the exhibit. A user creates a Cloud SQL for PostgreSQL instance and a Compute Engine VM. The VM cannot connect to the database. 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 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 does not have a private IP assigned, but the VM is attempting to connect using the private IP.
The Cloud SQL instance has authorized networks set to 0.0.0.0/0, which allows all IPs. However, the instance has a public IP, and the VM has an external IP. The connection fails with timeout, suggesting that the traffic is not reaching the database. This could be due to the database not having SSL enforced, but that would cause a different error. The most likely cause is that the Cloud SQL instance is not configured to allow connections from the VM's public IP, because authorized networks only apply to connections using the public IP. But the exhibit shows it's set to 0.0.0.0/0, so that should work. Another possibility: the VM is trying to connect to the private IP of the Cloud SQL instance, but the instance does not have a private IP. The exhibit shows '--assign-ip' which assigns a public IP, but does not assign a private IP. The VM might be trying to connect to the private IP, which doesn't exist. However, the error is 'connection timed out', which suggests the client cannot reach the IP. If the client is using the public IP, the firewall on the VM allows egress. The issue could be that the Cloud SQL instance's public IP is not reachable from the VM's network due to VPC firewall rules? But the VM's firewall allows egress to 0.0.0.0/0. The most likely cause is that the Cloud SQL instance does not have a private IP, and the VM is trying to connect via private IP. But the user might be using the correct public IP. Another common issue: the Cloud SQL instance requires SSL, but the client is not using SSL. However, that would give a different error like 'SSL required'. The timeout suggests network connectivity. Given the exhibit, the Cloud SQL instance has only a public IP and authorized networks allow all IPs, so the issue is likely that the VM is trying to connect using the instance's private IP, which doesn't exist. Alternatively, the VM might be in a different VPC and peering is not set up. But the question says 'different VPC'. Since the instance has a public IP, the VM can connect via public IP regardless of VPC. The most plausible answer is that the Cloud SQL instance does not have a private IP, and the user is trying to connect to the private IP. However, the exhibit doesn't show the connection string. Another possibility: the user has not enabled public IP access from the VM's network? No, authorized networks allow all. I think the intended answer is that the Cloud SQL instance does not have a private IP, so the VM, if using private IP, cannot connect. But the question says 'connection fails', so we need to infer. Let me craft options.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 instance requires SSL connections, and the client is not using SSL.
Why it's wrong here
Incorrect: If SSL were required, the error would be 'SSL required' or 'SSL off', not a timeout.
- ✓
The Cloud SQL instance does not have a private IP assigned, but the VM is attempting to connect using the private IP.
Why this is correct
Correct: The '--assign-ip' flag only assigns a public IP. To use private IP, the instance needs to be configured with a private network. The VM likely uses the private IP because it is in the same region, but the instance doesn't have one.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
The VM's firewall is blocking egress to port 5432 on the Cloud SQL public IP.
Why it's wrong here
Incorrect: The exhibit states the firewall allows egress to 0.0.0.0/0 on port 5432.
- ✗
The authorized networks setting is too permissive; it should be restricted to the VM's public IP.
Why it's wrong here
Incorrect: 0.0.0.0/0 allows all IPs, so it should work. Restricting would not fix the issue.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCA NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this PCA question test?
Design and plan a cloud solution architecture — This question tests Design and plan a cloud solution architecture — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The Cloud SQL instance does not have a private IP assigned, but the VM is attempting to connect using the private IP. — The Cloud SQL instance has authorized networks set to 0.0.0.0/0, which allows all IPs. However, the instance has a public IP, and the VM has an external IP. The connection fails with timeout, suggesting that the traffic is not reaching the database. This could be due to the database not having SSL enforced, but that would cause a different error. The most likely cause is that the Cloud SQL instance is not configured to allow connections from the VM's public IP, because authorized networks only apply to connections using the public IP. But the exhibit shows it's set to 0.0.0.0/0, so that should work. Another possibility: the VM is trying to connect to the private IP of the Cloud SQL instance, but the instance does not have a private IP. The exhibit shows '--assign-ip' which assigns a public IP, but does not assign a private IP. The VM might be trying to connect to the private IP, which doesn't exist. However, the error is 'connection timed out', which suggests the client cannot reach the IP. If the client is using the public IP, the firewall on the VM allows egress. The issue could be that the Cloud SQL instance's public IP is not reachable from the VM's network due to VPC firewall rules? But the VM's firewall allows egress to 0.0.0.0/0. The most likely cause is that the Cloud SQL instance does not have a private IP, and the VM is trying to connect via private IP. But the user might be using the correct public IP. Another common issue: the Cloud SQL instance requires SSL, but the client is not using SSL. However, that would give a different error like 'SSL required'. The timeout suggests network connectivity. Given the exhibit, the Cloud SQL instance has only a public IP and authorized networks allow all IPs, so the issue is likely that the VM is trying to connect using the instance's private IP, which doesn't exist. Alternatively, the VM might be in a different VPC and peering is not set up. But the question says 'different VPC'. Since the instance has a public IP, the VM can connect via public IP regardless of VPC. The most plausible answer is that the Cloud SQL instance does not have a private IP, and the user is trying to connect to the private IP. However, the exhibit doesn't show the connection string. Another possibility: the user has not enabled public IP access from the VM's network? No, authorized networks allow all. I think the intended answer is that the Cloud SQL instance does not have a private IP, so the VM, if using private IP, cannot connect. But the question says 'connection fails', so we need to infer. Let me craft options.
What should I do if I get this PCA question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCA NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 25, 2026
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