- A
Configure authorized networks with the subnet's CIDR range (if using public IP).
Authorized networks allow ingress from specified public IP ranges.
- B
Create a VPC firewall rule that blocks all traffic to the Cloud SQL instance's IP.
Why wrong: Cloud SQL is a managed service; its IP is not in the VPC, so firewall rules don't apply.
- C
Enable private IP on the Cloud SQL instance and connect from instances in the same VPC.
Private IP restricts access to the VPC network.
- D
Use VPC Service Controls to limit access to the Cloud SQL instance.
Why wrong: VPC Service Controls prevent data exfiltration but do not restrict network connectivity.
- E
Use Cloud SQL Proxy with IAM permissions to connect from authorized clients.
Cloud SQL Proxy uses IAM and can be configured to allow only specific clients.
Quick Answer
The answer is to use Authorized Networks, Private IP with VPC peering, and Cloud SQL Proxy with IAM permissions. Authorized Networks restrict public IP access by allowing only traffic from a specific CIDR range, such as your subnet’s IP block, directly blocking all other sources. Private IP with VPC peering places the Cloud SQL instance inside your VPC, making it reachable only from within that subnet without any public exposure. The Cloud SQL Proxy, combined with IAM permissions, provides encrypted, identity-based access from authorized clients, ensuring only Compute Engine instances with the correct service account can connect. On the Google Professional Cloud Security Engineer exam, this tests your understanding of network isolation versus identity-based controls—a common trap is confusing Authorized Networks (IP-based) with Private IP (VPC-native). Remember the mnemonic: “IP, Peering, Proxy” for the three layers of subnet restriction.
PCSE Configuring network security Practice Question
This PCSE practice question tests your understanding of configuring network security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 wants to restrict access to a Cloud SQL instance so that only Compute Engine instances in a specific VPC subnet can connect. Which THREE methods can be used to achieve this? (Choose THREE.)
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
Configure authorized networks with the subnet's CIDR range (if using public IP).
Option A is correct because authorized networks allow you to restrict access to a Cloud SQL instance with a public IP by specifying the CIDR range of the subnet. Only traffic originating from IP addresses within that range can connect to the instance, effectively limiting access to Compute Engine instances in that subnet.
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.
- ✓
Configure authorized networks with the subnet's CIDR range (if using public IP).
Why this is correct
Authorized networks allow ingress from specified public IP ranges.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a VPC firewall rule that blocks all traffic to the Cloud SQL instance's IP.
Why it's wrong here
Cloud SQL is a managed service; its IP is not in the VPC, so firewall rules don't apply.
- ✓
Enable private IP on the Cloud SQL instance and connect from instances in the same VPC.
Why this is correct
Private IP restricts access to the VPC network.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use VPC Service Controls to limit access to the Cloud SQL instance.
Why it's wrong here
VPC Service Controls prevent data exfiltration but do not restrict network connectivity.
- ✓
Use Cloud SQL Proxy with IAM permissions to connect from authorized clients.
Why this is correct
Cloud SQL Proxy uses IAM and can be configured to allow only specific clients.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that VPC firewall rules can control traffic to managed services like Cloud SQL, but in reality, Cloud SQL instances are not part of your VPC's network stack and are not subject to VPC firewall rules.
Detailed technical explanation
How to think about this question
Cloud SQL private IP uses RFC 1918 addresses from a VPC subnet, and connectivity relies on VPC peering or Shared VPC, not firewall rules. The Cloud SQL Proxy creates an encrypted tunnel using the Cloud SQL Auth proxy library, which authenticates via IAM and then connects over TCP to the instance's private or public IP, bypassing network-based restrictions like authorized networks.
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 PCSE question test?
Configuring network security — This question tests Configuring network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure authorized networks with the subnet's CIDR range (if using public IP). — Option A is correct because authorized networks allow you to restrict access to a Cloud SQL instance with a public IP by specifying the CIDR range of the subnet. Only traffic originating from IP addresses within that range can connect to the instance, effectively limiting access to Compute Engine instances in that subnet.
What should I do if I get this PCSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCSE 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 PCSE exam.
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