Google PCA Manage and provision cloud infrastructure Practice Question
A company has Compute Engine instances in us-east1-a and us-east1-b zones. They want to allow communication between these instances with minimal latency and no additional cost. What is the best networking approach?
⚠ Common exam trap
The trap here is that candidates may overcomplicate the solution by thinking they need separate networks or VPNs for zone-to-zone communication, when in fact a single VPC inherently supports flat, cost-free internal connectivity across zones.
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 a single VPC network that includes both zones.
A single VPC network spans all regions and zones, allowing instances in different zones (us-east1-a and us-east1-b) to communicate using internal IP addresses with low latency and no additional cost. This is because VPC networks provide flat, global networking by default, and traffic between zones within the same VPC uses Google's internal backbone without incurring egress charges.
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 VPC Network Peering between two separate VPC networks.
Why it's wrong here
VPC Network Peering connects separate VPC networks, but the Compute Engine instances are already within the same VPC project and only differ by zone (us-east1-a and us-east1-b). Peering would introduce unnecessary routing hops and configuration overhead, failing to achieve the minimal latency that internal zone-to-zone traffic within a single VPC provides at no cost. This option is tempting because VPC Peering is the correct choice when instances reside in different VPC networks (e.g., across projects or organisations) that need private IP communication without a VPN or internet gateway.
- ✓
Use a single VPC network that includes both zones.
Why this is correct
A single VPC network spans all zones within a region, so instances in us-east1-a and us-east1-b communicate over Google's internal network using private RFC 1918 addresses. Traffic stays within the region, giving low latency with no additional egress cost.
- ✗
Create a new subnet in each zone and use Cloud NAT.
Why it's wrong here
Subnets are regional, so both zones already share one; Cloud NAT provides outbound internet address translation, not inter-zone routing. It tempts teams needing egress for private instances without external IPs, but intra-VPC traffic already routes across zones at no cost.
- ✗
Set up a Cloud VPN between the zones.
Why it's wrong here
Cloud VPN encrypts traffic between external networks or on-premises, not between zones inside one VPC, and adds gateways, tunnels and cost. It appeals when connecting separate networks securely, but instances in different zones of the same VPC communicate directly over Google's network.
Go deeper
Related to this question
Learn chapter
Billing, Budgets, and Cost Management
Key term
VPC
A Virtual Private Cloud (VPC) is a logically isolated section of a cloud provider's network where you can launch and manage resources like servers and databases with complete control over IP addressing, subnets, route tables, and security.
Key term
Latency
Latency is the time delay between a request being sent over a network and the response being received, often measured in milliseconds.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCA 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 PCA exam.