PCNE Implementing a Virtual Private Cloud Practice Question
A company is designing a network for a critical application that requires sub-millisecond latency between two Compute Engine instances. The instances are located in different zones within the same region. Which VPC configuration will provide the lowest latency?
⚠ Common exam trap
Google Cloud often tests the misconception that VPC Network Peering provides equivalent latency to a single VPC, but the trap here is that peering adds a logical routing boundary and potential latency overhead, making a single VPC with internal IPs the only option for guaranteed sub-millisecond performance.
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 both instances in the same VPC, using internal IP addresses.
Placing both Compute Engine instances in the same VPC and using internal IP addresses ensures traffic stays within Google's private network backbone, bypassing any external gateways or internet hops. This configuration leverages Google's internal routing with sub-millisecond latency between zones in the same region, as traffic is forwarded at the hypervisor level without encapsulation or additional network hops.
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 VPC Network Peering between two different VPCs.
Why it's wrong here
Peering adds a slight overhead; same VPC is better.
- ✗
Place instances in different VPCs and use a VPN between them.
Why it's wrong here
VPN adds encryption overhead and extra latency.
- ✓
Place both instances in the same VPC, using internal IP addresses.
Why this is correct
Internal IPs stay within Google's network, providing lowest latency.
- ✗
Assign external IP addresses to both instances and communicate over the internet.
Why it's wrong here
External IPs traverse the internet gateway, increasing latency.
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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.