The answer is a unique external IP address for each VPN gateway, along with a Cloud Router configured with BGP and at least two VPN tunnels. This combination is required for highly available Cloud VPN with dynamic routing because BGP enables automatic route exchange and failover between the on-premises network and Google Cloud; without BGP, the VPN would rely on static routes that cannot adapt to gateway or link failures, breaking high availability. On the Google Professional Cloud Network Engineer exam, this question tests your understanding that dynamic routing is synonymous with BGP-based route advertisement, and a common trap is assuming that two tunnels alone suffice—they must each have a unique external IP and be paired with a Cloud Router to support BGP sessions. A useful memory tip is “Two tunnels, two IPs, one Cloud Router” to recall the three essentials for HA dynamic VPN.
PCNE Practice Question: Designing, planning, and prototyping a GCP network
This PCNE practice question tests your understanding of designing, planning, and prototyping a gcp network. 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.
Which THREE of the following are required to set up a highly available Cloud VPN with dynamic routing? (Choose THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A Cloud Router with BGP configured for each tunnel.
A is correct because Cloud VPN with dynamic routing requires a Cloud Router with BGP configured for each tunnel. BGP enables the exchange of routes between the on-premises network and Google Cloud, allowing automatic failover and route propagation. Without BGP, dynamic routing cannot function, and the VPN would rely on static routes, which do not support high availability.
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.
✓
A Cloud Router with BGP configured for each tunnel.
Read the scenario before looking for a memorised answer.
✓
Two Cloud VPN gateways in different regions.
Why this is correct
HA VPN uses two gateways in different zones for redundancy.
Related concept
Read the scenario before looking for a memorised answer.
✗
Redundant on-premises VPN gateways.
Why it's wrong here
Redundant on-premises gateways are recommended but not a requirement for HA VPN definition.
✗
Two VPN tunnels from each gateway to the on-premises router.
Why it's wrong here
HA VPN requires one tunnel per gateway, not two per gateway.
✓
A unique external IP address for each VPN gateway.
Why this is correct
Each gateway requires a unique public IP for the tunnels.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think redundant on-premises gateways or multiple tunnels per gateway are required for high availability, but Google Cloud's HA VPN only requires two gateways in different regions, each with a unique IP and a Cloud Router with BGP, while on-premises redundancy is optional and not a Cloud-side requirement.
Detailed technical explanation
How to think about this question
Under the hood, Cloud VPN with dynamic routing uses BGP sessions over IPsec tunnels to exchange routes via the Cloud Router. Each Cloud Router can support multiple BGP sessions, and the VPN gateway uses a unique external IP address per gateway to establish separate tunnels. In a real-world scenario, if one gateway fails, BGP withdraws the routes, and traffic automatically shifts to the other gateway via the remaining BGP session, ensuring sub-second failover.
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.
Designing, planning, and prototyping a GCP network — This question tests Designing, planning, and prototyping a GCP network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A Cloud Router with BGP configured for each tunnel. — A is correct because Cloud VPN with dynamic routing requires a Cloud Router with BGP configured for each tunnel. BGP enables the exchange of routes between the on-premises network and Google Cloud, allowing automatic failover and route propagation. Without BGP, dynamic routing cannot function, and the VPN would rely on static routes, which do not support high availability.
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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