The answer is enabling BGP for dynamic routing, using two tunnels from each VPN gateway, and configuring each tunnel to connect to a separate Cloud Router. BGP is essential because it allows the Cloud VPN to automatically detect path failures and reroute traffic between tunnels without manual intervention, unlike static routes which cannot adapt to network changes. On the Google Professional Cloud Network Engineer exam, this question tests your understanding of high availability design principles for hybrid connectivity, often appearing as a multi-select scenario where static routing is a common trap. A key memory tip is to think of BGP as the “brain” that enables failover and load balancing across your two tunnels, while the dual-tunnel and dual-Cloud Router setup provides physical redundancy. Remember the mnemonic “Two Tunnels, Two Routers, One BGP” to recall the three factors quickly.
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 factors should be considered when designing a Cloud VPN for high availability? (Choose 3.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable BGP for dynamic routing
Enabling BGP (Border Gateway Protocol) for dynamic routing is correct because it allows the Cloud VPN to automatically detect and route around failures. BGP exchanges route information between the on-premises router and the Cloud Router, enabling dynamic failover and load balancing across multiple tunnels. Without BGP, you would rely on static routes, which cannot adapt to network changes and require manual intervention during a failure.
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.
✓
Enable BGP for dynamic routing
Why this is correct
BGP allows automatic route advertisement and failover.
Related concept
Read the scenario before looking for a memorised answer.
✓
Deploy VPN gateways in different regions
Why this is correct
Provides resilience against regional outages.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use two tunnels from each VPN gateway
Why this is correct
Each gateway should have two tunnels to different on-premises endpoints for redundancy.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use static routes for failover
Why it's wrong here
Static routes do not automatically failover; BGP is required for HA.
✗
Use a single Cloud Router for simplicity
Why it's wrong here
A single Cloud Router creates a single point of failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think static routes with a higher metric can provide failover, but they fail to realize that static routes cannot dynamically detect a tunnel failure unless combined with a health check mechanism, which is not as reliable or fast as BGP's built-in path selection and withdrawal.
Detailed technical explanation
How to think about this question
BGP uses the MED (Multi-Exit Discriminator) and AS path attributes to influence path selection, allowing you to prefer one tunnel over another for traffic engineering. In a high-availability design, you typically deploy two VPN tunnels from each gateway to different on-premises endpoints, and BGP sessions are established over each tunnel. If a tunnel fails, BGP withdraws the routes, and traffic automatically shifts to the remaining tunnels without any manual intervention, achieving sub-second failover in many cases.
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: Enable BGP for dynamic routing — Enabling BGP (Border Gateway Protocol) for dynamic routing is correct because it allows the Cloud VPN to automatically detect and route around failures. BGP exchanges route information between the on-premises router and the Cloud Router, enabling dynamic failover and load balancing across multiple tunnels. Without BGP, you would rely on static routes, which cannot adapt to network changes and require manual intervention during a failure.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company wants to connect on-premise to GCP via Cloud VPN with dynamic routing. They have two on-prem routers for redundancy. Which configuration ensures automatic failover?
easy
A.Create two VPN tunnels each with static routes pointing to the other router
B.Create one VPN tunnel with BGP and two interfaces
✓ C.Create two VPN tunnels using Cloud Router with BGP and the same ASN
D.Create two VPN tunnels with BGP but different ASNs on each tunnel
Why C: Option C is correct because creating two VPN tunnels with Cloud Router using BGP and the same ASN on both on-prem routers enables dynamic routing and automatic failover. Cloud Router establishes BGP sessions with each on-prem router, and when both tunnels advertise the same routes with the same ASN, Cloud Router can detect a BGP session failure and automatically route traffic through the remaining healthy tunnel. This setup ensures seamless failover without manual intervention.
Variation 2. A company plans to connect an on-premises network to Google Cloud using HA VPN with dynamic routing (BGP). The on-premises side supports BGP and has two independent routers for redundancy. The company wants to ensure failover within seconds if one tunnel goes down. Which configuration meets this requirement?
medium
✓ A.Create two Cloud VPN gateways in different regions, each with a tunnel to a different on-premises router, and configure a separate Cloud Router on each gateway with BGP.
B.Create two VPN tunnels from one Cloud VPN gateway to both on-premises routers, and configure one Cloud Router with active/passive BGP.
C.Create two Cloud VPN gateways in the same region, each with a tunnel to a different on-premises router, and use static routing with route metrics for failover.
D.Create two VPN tunnels from one Cloud VPN gateway to both on-premises routers, and configure a single Cloud Router with BGP.
Why A: Option A is correct because deploying two Cloud VPN gateways in different regions with separate Cloud Routers ensures true regional redundancy. If one gateway or its tunnel fails, BGP sessions on the other gateway remain active, and Google Cloud's network can immediately route traffic via the surviving path. This architecture meets the sub-second failover requirement by avoiding a single point of failure at the gateway level and leveraging BGP's fast convergence.
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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.
Question Discussion
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