PCNE Implementing VPC Instances Practice Question
An organization needs to deploy a multi-tier web application on Compute Engine. The web tier must be accessible from the internet, while the database tier must only be accessible from the web tier. The security team requires a defense-in-depth approach. Which THREE measures should be implemented? (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
✓
Use firewall rules to allow ingress from the web subnet to the database subnet on the database port (e.g., 3306)
Defense-in-depth includes using separate subnets, firewall rules, and possibly service accounts. Tags help target rules. Using separate subnets isolates tiers. Firewall rules control traffic between tiers. Using service accounts can further restrict access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Place web and database instances in the same subnet to minimize latency
Why it's wrong here
Placing them in the same subnet reduces isolation and defeats defense-in-depth.
- ✓
Use firewall rules to allow ingress from the web subnet to the database subnet on the database port (e.g., 3306)
Why this is correct
This restricts database access to only the web tier.
- ✓
Create separate subnets for web and database tiers
Why this is correct
Separate subnets provide network segmentation and allow granular firewall rules.
- ✗
Assign external IPs to database instances for easy maintenance
Why it's wrong here
Assigning external IPs to database instances increases the attack surface and violates least privilege.
- ✓
Use firewall rules to allow ingress from the internet to the web subnet on port 80/443
Why this is correct
This allows internet traffic to the web tier.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNE 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 PCNE exam.