- A
Use a single subnet for all tiers. Assign public IPs to all instances. Use firewall rules to restrict access between tiers. Use a proxy VM for outbound internet from app/db tiers.
Why wrong: Assigning public IPs to app/db is insecure, and a proxy VM adds complexity.
- B
Create separate VPCs for each tier. Use VPC peering to connect them. Use firewall rules to allow traffic. Use a bastion host for SSH access to app/db tiers.
Why wrong: Multiple VPCs increase complexity and management overhead.
- C
Place all tiers in the same VPC. Use firewall rules to restrict access. Assign public IPs to web tier instances and private IPs to app/db tiers. Configure Cloud NAT for app/db tiers.
Why wrong: Assigning public IPs to web tier is correct, but app/db tiers should not have public IPs; Cloud NAT is for outbound, not inbound.
- D
Place web tier in a public subnet with public IPs. Place app/db tiers in private subnets with no public IPs. Use firewall rules to allow traffic from web to app, and app to db. Configure Cloud NAT for private subnets.
This uses public subnets for web, private subnets for app/db, firewall rules for least privilege, and Cloud NAT for outbound access.
Quick Answer
The correct architecture uses a single VPC with public and private subnets, placing the web tier in the public subnet with public IPs and the app and database tiers in private subnets without public IPs, then configuring Cloud NAT for outbound internet access from the private instances. This design minimizes operational overhead because it avoids complex transitive routing or separate VPC peering, relying instead on VPC firewall rules to restrict traffic flows from web to app and app to database, while Cloud NAT provides scalable, managed outbound connectivity without requiring a proxy VM. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of how to design multi-tier VPC architecture with private subnets and Cloud NAT, often appearing as a trap where candidates mistakenly add public IPs to all tiers or use a NAT instance instead of Cloud NAT. The key insight is that Cloud NAT is a regional, Google-managed resource that eliminates the operational burden of patching and scaling a proxy, making it the least overhead choice for private subnet outbound access. Memory tip: think “public web, private app, Cloud NAT for the outbound gap.”
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 is deploying a multi-tier application on Google Cloud. The web tier must be accessible from the internet, while the application and database tiers must only be accessible from the web tier. The security team wants to use VPC firewall rules and Cloud NAT for outbound internet access from private instances. Which architecture meets these requirements with the least operational overhead?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"least"Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
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
Place web tier in a public subnet with public IPs. Place app/db tiers in private subnets with no public IPs. Use firewall rules to allow traffic from web to app, and app to db. Configure Cloud NAT for private subnets.
Option D is correct because it uses a single VPC with separate public and private subnets, which minimizes operational overhead while meeting the security requirements. The web tier in the public subnet gets public IPs for internet access, while the app and database tiers in private subnets have no public IPs and rely on Cloud NAT for outbound internet. Firewall rules restrict traffic to only the necessary flows (web→app, app→db), and Cloud NAT provides scalable outbound connectivity without managing a proxy VM.
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.
- ✗
Use a single subnet for all tiers. Assign public IPs to all instances. Use firewall rules to restrict access between tiers. Use a proxy VM for outbound internet from app/db tiers.
- ✗
Create separate VPCs for each tier. Use VPC peering to connect them. Use firewall rules to allow traffic. Use a bastion host for SSH access to app/db tiers.
Why it's wrong here
Multiple VPCs increase complexity and management overhead.
- ✗
Place all tiers in the same VPC. Use firewall rules to restrict access. Assign public IPs to web tier instances and private IPs to app/db tiers. Configure Cloud NAT for app/db tiers.
- ✓
Place web tier in a public subnet with public IPs. Place app/db tiers in private subnets with no public IPs. Use firewall rules to allow traffic from web to app, and app to db. Configure Cloud NAT for private subnets.
Why this is correct
This uses public subnets for web, private subnets for app/db, firewall rules for least privilege, and Cloud NAT for outbound access.
Clue confirmation
The clue word "least" 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
Google Cloud often tests the misconception that separate VPCs or multiple subnets are required for security, when in fact a single VPC with proper subnetting and firewall rules is simpler and meets the same security goals with less operational overhead.
Detailed technical explanation
How to think about this question
Cloud NAT uses Source Network Address Translation (SNAT) to allow private instances to initiate outbound connections to the internet, but it does not allow inbound connections from the internet, which is exactly the requirement for the app and database tiers. The firewall rules in VPC are stateful, meaning that if you allow inbound traffic from the web tier to the app tier, the return traffic is automatically allowed, simplifying rule configuration. In a real-world scenario, you might also use Private Google Access to allow private instances to reach Google APIs without needing Cloud NAT, but Cloud NAT is required for general internet access.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
- →
Configuring network security — study guide chapter
Learn the concepts, then practise the questions
- →
Configuring network security practice questions
Targeted practice on this topic area only
- →
All PCSE questions
500 questions across all exam domains
- →
Google Professional Cloud Security Engineer study guide
Full concept coverage aligned to exam objectives
- →
PCSE practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related PCSE practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Configuring network security practice questions
Practise PCSE questions linked to Configuring network security.
Configuring access within a cloud solution environment practice questions
Practise PCSE questions linked to Configuring access within a cloud solution environment.
Ensuring data protection practice questions
Practise PCSE questions linked to Ensuring data protection.
Managing operations in a cloud solution environment practice questions
Practise PCSE questions linked to Managing operations in a cloud solution environment.
Supporting compliance requirements practice questions
Practise PCSE questions linked to Supporting compliance requirements.
PCSE fundamentals practice questions
Practise PCSE questions linked to PCSE fundamentals.
PCSE scenario practice questions
Practise PCSE questions linked to PCSE scenario.
PCSE troubleshooting practice questions
Practise PCSE questions linked to PCSE troubleshooting.
Practice this exam
Start a free PCSE practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: Place web tier in a public subnet with public IPs. Place app/db tiers in private subnets with no public IPs. Use firewall rules to allow traffic from web to app, and app to db. Configure Cloud NAT for private subnets. — Option D is correct because it uses a single VPC with separate public and private subnets, which minimizes operational overhead while meeting the security requirements. The web tier in the public subnet gets public IPs for internet access, while the app and database tiers in private subnets have no public IPs and rely on Cloud NAT for outbound internet. Firewall rules restrict traffic to only the necessary flows (web→app, app→db), and Cloud NAT provides scalable outbound connectivity without managing a proxy VM.
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.
Are there clue words in this question I should notice?
Yes — watch for: "least". You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
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 →
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.
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.