The answer is two external IP addresses for the VPN gateway and a Cloud Router with BGP configured in the same region. An HA VPN tunnel requires two external IP addresses to establish two separate tunnels to your on-premises gateway, ensuring active-active or active-passive failover. The Cloud Router with BGP is essential because it dynamically exchanges routes with the on-premises network, allowing automatic failover and load balancing across the two tunnels without manual intervention. On the Google Professional Cloud Network Engineer exam, this question tests your understanding that HA VPN is fundamentally a dynamic routing solution—static routes are not supported. A common trap is assuming a single external IP suffices, but redundancy demands two. Another pitfall is forgetting that the Cloud Router must reside in the same region as the VPN gateway. Memory tip: think “two tunnels, two IPs, one router with BGP” to recall the core prerequisites.
PCNE Implementing hybrid interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 two of the following are prerequisites for configuring an HA VPN tunnel to an on-premises network? (Choose two.)
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 in the same region as the VPN gateway.
B is correct because an HA VPN tunnel uses dynamic routing via BGP to provide active-active or active-passive failover. A Cloud Router with BGP configured in the same region as the VPN gateway is required to exchange routes with the on-premises network, enabling automatic failover and load balancing across the two tunnels.
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.
Read the scenario before looking for a memorised answer.
✗
A pre-shared key that is at least 20 characters long.
Why it's wrong here
There is no specific length requirement for the PSK.
✗
An on-premises VPN device that supports static routing only.
Why it's wrong here
HA VPN requires BGP, so the on-premises device must support dynamic routing.
✓
Two external IP addresses for the VPN gateway.
Why this is correct
HA VPN uses two interfaces with two external IPs for redundancy.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that HA VPN requires a VLAN attachment or static routing, but the key requirement is a Cloud Router with BGP in the same region to support dynamic routing and failover.
Detailed technical explanation
How to think about this question
HA VPN creates two tunnels (one per external IP address) to the same on-premises peer, each with its own BGP session. The Cloud Router manages route advertisements and uses BGP timers (e.g., keepalive interval of 20 seconds, hold time of 60 seconds) to detect tunnel failure and reroute traffic. In a real-world scenario, if one tunnel drops, BGP withdraws the routes and the other tunnel takes over within seconds, providing high availability 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
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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: A Cloud Router with BGP configured in the same region as the VPN gateway. — B is correct because an HA VPN tunnel uses dynamic routing via BGP to provide active-active or active-passive failover. A Cloud Router with BGP configured in the same region as the VPN gateway is required to exchange routes with the on-premises network, enabling automatic failover and load balancing across the two tunnels.
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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