The answer is to configure active-active BGP with multiple sessions using different ASNs. This is correct because each tunnel in an HA VPN setup is treated as an independent BGP session, and assigning different ASNs to each session prevents route flapping and allows BGP to withdraw routes cleanly when a tunnel fails. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of how BGP path selection and failover work across multiple tunnels—a common trap is assuming that using the same ASN for all sessions is acceptable, which can cause BGP to ignore alternate paths due to the AS path loop prevention mechanism. For the HA VPN active-active configuration best practice, remember that each tunnel must have its own unique ASN to ensure automatic failover and load balancing without manual intervention. A helpful memory tip: “Different ASN, different path—one fails, traffic shifts fast.”
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.
A company is setting up HA VPN between on-premises and Google Cloud. They have two Cloud VPN gateways with two tunnels each. They want to ensure automatic failover if one tunnel goes down. Which BGP configuration is a best practice?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure active-active BGP with multiple sessions using different ASNs.
Option B is correct because active-active BGP with multiple sessions using different ASNs allows each tunnel to be treated as an independent path. If one tunnel fails, BGP withdraws the routes learned over that session, and traffic automatically shifts to the remaining tunnels without manual intervention. This configuration provides true automatic failover and load balancing, which is a best practice for HA VPN with multiple 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.
✗
Configure active-passive BGP with a single session.
Why it's wrong here
Active-passive does not utilize both tunnels for failover and may have slower convergence.
✓
Configure active-active BGP with multiple sessions using different ASNs.
Why this is correct
Active-active BGP with multiple sessions allows both tunnels to be active and provides automatic failover.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use policy-based routing to fail between tunnels.
Why it's wrong here
Policy-based routing is not recommended for HA VPN; BGP with dynamic routing is preferred.
✗
Use static routes with a primary and backup route.
Why it's wrong here
Static routes do not provide automatic failover in case of tunnel failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume active-passive BGP is sufficient for HA, but in Google Cloud's HA VPN, active-active BGP with multiple sessions and different ASNs is required to achieve automatic failover across multiple tunnels without relying on static route manipulation.
Detailed technical explanation
How to think about this question
In Google Cloud HA VPN, each Cloud VPN gateway supports up to four tunnels (two per gateway). When using active-active BGP, each tunnel is associated with a separate BGP session, and each session uses a unique ASN (often private ASNs) to ensure route diversity. Under the hood, BGP uses the MED, Local Preference, and AS_PATH attributes to select the best path; when a tunnel fails, the BGP session goes down, causing the learned routes to be withdrawn, and the remaining sessions' routes become preferred. In a real-world scenario, this design allows for seamless failover even during maintenance or transient network issues, as BGP's keepalive mechanism detects failures within seconds.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: Configure active-active BGP with multiple sessions using different ASNs. — Option B is correct because active-active BGP with multiple sessions using different ASNs allows each tunnel to be treated as an independent path. If one tunnel fails, BGP withdraws the routes learned over that session, and traffic automatically shifts to the remaining tunnels without manual intervention. This configuration provides true automatic failover and load balancing, which is a best practice for HA VPN with multiple 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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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