The answer is to deploy a single Cloud VPN gateway with two interfaces, each with its own external IP, and configure two BGP sessions to the single on-premises device. This configuration is correct because it creates an active/active HA VPN setup where the two interfaces and BGP sessions provide path redundancy; if one interface or session fails, traffic automatically fails over to the other, maximizing availability without requiring a second on-premises device. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of HA VPN’s ability to achieve high availability with a single on-premises peer, a common trap being the mistaken assumption that you need two separate gateways or regions. The key technical concept is that the Cloud VPN gateway’s two interfaces act as independent endpoints, each terminating a BGP session to the same on-premises router, allowing Google Cloud to handle failover at the network layer. A helpful memory tip is “two IPs, one box, active-active BGP hops” — the single gateway’s dual interfaces are the secret to resilient connectivity.
PCNE Implementing hybrid interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An enterprise uses HA VPN to connect their on-premises network to Google Cloud. The on-premises side has a single VPN device that supports BGP. They want to maximize availability. What is the recommended Google Cloud configuration?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deploy a single Cloud VPN gateway with two interfaces, each with its own external IP, and configure two BGP sessions to the single on-premises device.
Option C is correct because it provides high availability by using a single Cloud VPNgateway with two interfaces, each with its own external IP, and two BGP sessions to the on-premises device. This configuration allows active/active failover: if one interface or BGP session fails, traffic automatically switches to the other, maximizing availability without requiring multiple regions.
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.
✗
Deploy two Cloud VPN gateways in different regions to provide regional failover.
Why it's wrong here
Regional failover is not standard for HA VPN; also adds complexity.
✗
Deploy a single Cloud VPN gateway with one interface and one BGP session.
Why it's wrong here
This does not provide redundancy.
✓
Deploy a single Cloud VPN gateway with two interfaces, each with its own external IP, and configure two BGP sessions to the single on-premises device.
Why this is correct
This provides interface-level redundancy and achieves maximal availability with a single on-premises device.
Related concept
Read the scenario before looking for a memorised answer.
✗
Deploy a single Cloud VPN gateway with two interfaces, but only use one BGP session for simplicity.
Why it's wrong here
Using only one BGP session negates the redundancy benefit of two interfaces.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that high availability requires multiple regions or gateways, but the trap here is that a single HA VPNgateway with dual interfaces and dual BGP sessions provides sufficient redundancy for a single on-premises device, avoiding unnecessary complexity.
Detailed technical explanation
How to think about this question
HA VPN in Google Cloud uses two interfaces on a single gateway, each with a unique external IP, and establishes two BGP sessions to the on-premises router. Under the hood, Cloud Router uses ECMP (Equal-Cost Multi-Path) routing to load-balance traffic across both tunnels, and BGP fast failover (with hold timers typically set to 10 seconds) ensures rapid convergence if a tunnel or session fails. In a real-world scenario, if one on-premises interface fails, BGP withdraws the routes, and traffic shifts to the remaining tunnel without manual intervention.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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.
Implementing hybrid interconnectivity — This question tests Implementing hybrid interconnectivity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy a single Cloud VPN gateway with two interfaces, each with its own external IP, and configure two BGP sessions to the single on-premises device. — Option C is correct because it provides high availability by using a single Cloud VPN gateway with two interfaces, each with its own external IP, and two BGP sessions to the on-premises device. This configuration allows active/active failover: if one interface or BGP session fails, traffic automatically switches to the other, maximizing availability without requiring multiple regions.
What should I do if I get this PCNE 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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Question Discussion
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