The correct next step is to verify that the routes learned via BGP are being propagated to the VPC network by examining Cloud Router details. Even though the BGP session is established and routes appear on the on-premises router, Cloud Router acts as the BGP speaker for the VPC and must explicitly advertise those learned routes into the VPC’s dynamic routing tables. If propagation is blocked—due to route filters, custom route advertisements, or misconfigured priority—traffic from on-premises will fail to reach Google Cloud resources. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding that a healthy BGP session does not guarantee end-to-end routing; the Cloud Router is the critical bridge between the VPN tunnel and the VPC. A common trap is assuming that a “BGP established” state means routes are automatically injected into the VPC. To remember: BGP up ≠ routes in VPC—always check Cloud Router’s advertised routes and the VPC’s effective routes.
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 using Cloud VPN to connect to Google Cloud. They notice that traffic from their on-premises network to Google Cloud is not being routed correctly after a recent change. On the on-premises router, they verify that the BGP session is established and routes are received. Which step should they take next to troubleshoot?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify that the routes learned via BGP are being propagated to the VPC network by examining Cloud Router details
Since the BGP session is established and routes are received on the on-premises router, the issue is likely that those routes are not being propagated into the VPC network. Cloud Router acts as the BGP speaker for the VPC; even if the VPN tunnel is up and BGP peering is successful, the learned routes must be advertised into the VPC’s routing tables. Verifying Cloud Router details (e.g., using `gcloud compute routers get-status` or checking the Cloud Console) confirms whether the routes are being accepted and propagated, which directly addresses the routing 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.
✓
Verify that the routes learned via BGP are being propagated to the VPC network by examining Cloud Router details
Why this is correct
Routes learned via BGP must be propagated to the VPC. Cloud Router shows advertised and learned routes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Check the on-premises firewall logs
Why it's wrong here
Firewall logs might show blocked traffic, but first confirm routing is correct.
✗
Disable and re-enable the VPN tunnel
Why it's wrong here
This is disruptive and may not resolve underlying routing issues.
✗
Check the tunnel status in Cloud Console
Why it's wrong here
Tunnel status might be up, but routing issues often stem from route propagation or firewall.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a working BGP session and tunnel status guarantee correct routing, but the real failure point is the propagation of learned routes into the VPC’s routing tables, which requires explicit verification of Cloud Router’s learned routes and advertisements.
Trap categories for this question
Command / output trap
Firewall logs might show blocked traffic, but first confirm routing is correct.
Detailed technical explanation
How to think about this question
Cloud Router uses BGP to exchange routes between the on-premises network and the VPC, but the routes learned from the peer must be accepted and propagated into the VPC’s dynamic routing. By default, Cloud Router applies route advertisement policies and can filter routes based on priority or custom route advertisements. A common subtle issue is that the on-premises router may be sending routes with a BGP community that Cloud Router is configured to reject, or the VPC’s dynamic routing mode (regional vs. global) may limit route propagation to specific subnets.
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.
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: Verify that the routes learned via BGP are being propagated to the VPC network by examining Cloud Router details — Since the BGP session is established and routes are received on the on-premises router, the issue is likely that those routes are not being propagated into the VPC network. Cloud Router acts as the BGP speaker for the VPC; even if the VPN tunnel is up and BGP peering is successful, the learned routes must be advertised into the VPC’s routing tables. Verifying Cloud Router details (e.g., using `gcloud compute routers get-status` or checking the Cloud Console) confirms whether the routes are being accepted and propagated, which directly addresses the routing 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.
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Question Discussion
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