The answer is to use multiple VPN tunnels with equal BGP metrics, specifically by lowering the BGP Multi-Exit Discriminator (MED) value on the primary tunnel. This works because BGP MED influences the best-path selection process, making the tunnel with the lower MED more preferred; when the primary tunnel fails, BGP immediately withdraws the route and the backup tunnel—already known with a higher MED—is selected without waiting for hold timers to expire, drastically reducing cloud VPN failover time. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of how BGP attributes and timers interact in dynamic routing, often appearing as a multi-select question where you must distinguish MED manipulation from timer adjustments. A common trap is assuming only timer changes affect failover speed, but MED provides a proactive path preference that bypasses timer delays. Remember the mnemonic: “Lower MED, faster lead—no timers, no bleed.”
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 organization is using Cloud VPN with dynamic routing and wants to improve failover time between two VPN tunnels. Which THREE configuration changes can help reduce failover time?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set a lower BGP MED value on the primary tunnel
Option A is correct because lowering the BGP Multi-Exit Discriminator (MED) value on the primary tunnel makes it more preferred by the BGP best-path selection process. When the primary tunnel fails, BGP withdraws the route, and the backup tunnel (with a higher MED) is immediately used without waiting for timers to expire. This reduces failover time by ensuring the backup path is already known and only needs to be selected upon withdrawal.
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.
✓
Set a lower BGP MED value on the primary tunnel
Why this is correct
Lower MED makes the primary path preferred, allowing faster fallback.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the BGP keepalive interval to reduce overhead
Why it's wrong here
Increasing keepalive interval would increase failover detection time.
✓
Configure BGP timers with lower values for faster detection
Why this is correct
Lower BGP timers reduce the time to detect a failure.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add static routes with a higher priority than BGP routes
Why it's wrong here
Static routes would not dynamically failover with BGP.
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 increasing keepalive intervals improves performance, when in fact it delays failure detection and increases failover time.
Detailed technical explanation
How to think about this question
BGP timers, such as the hold timer (default 90 seconds) and keepalive interval (default 30 seconds), directly impact failure detection speed. Lowering these timers (e.g., using 'timers bgp 3 9' for 3-second keepalive and 9-second hold) can reduce detection to under 10 seconds, but must be balanced against CPU overhead and network stability. In dynamic routing with Cloud VPN, BGP fast external failover (enabled by default) also helps by immediately resetting the BGP session when the interface goes down, further reducing failover time.
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: Set a lower BGP MED value on the primary tunnel — Option A is correct because lowering the BGP Multi-Exit Discriminator (MED) value on the primary tunnel makes it more preferred by the BGP best-path selection process. When the primary tunnel fails, BGP withdraws the route, and the backup tunnel (with a higher MED) is immediately used without waiting for timers to expire. This reduces failover time by ensuring the backup path is already known and only needs to be selected upon withdrawal.
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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