The correct action is to configure BGP MED values on the on-premises router for the prefixes advertised to the Cloud Router. This works because BGP Multi-Exit Discriminator (MED) is a standard metric used to influence inbound traffic path selection when multiple connections exist between two autonomous systems, such as your on-premises network and Google Cloud via Partner Interconnect. By setting a lower MED value on the on-premises router for the specific subnet prefixes, you signal Google Cloud to prefer that particular VLAN attachment, steering traffic away from the suboptimal path. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of how to influence routing preference on Partner Interconnect without modifying Cloud Router configurations—a common trap is to mistakenly adjust AS path prepending on the Cloud side, which affects outbound traffic, not inbound. Remember the memory tip: MED is the "inbound influencer" for multi-homed connections, so lower MED means "come this way."
PCNE Implementing hybrid interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 Partner Interconnect to connect their data center to Google Cloud. They notice that traffic from their on-premises network to a specific subnet in VPC is taking a suboptimal path. Which action should they take to influence the routing preference?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure BGP MED values on the on-premises router for the prefixes advertised to the Cloud Router.
Option D is correct because BGP MED (Multi-Exit Discriminator) is the standard mechanism for influencing inbound traffic path selection when multiple connections exist between two autonomous systems. By setting a lower MED value on the on-premises router for prefixes advertised to the Cloud Router, the on-premises network can signal Google Cloud to prefer that specific VLAN attachment for traffic destined to the subnet, thereby correcting the suboptimal path.
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.
✗
Use route priorities on the Cloud Router for the learned routes.
Why it's wrong here
Route priorities in Cloud Router are used for routes learned from multiple Cloud Routers, not for BGP learned routes.
✗
Change the VLAN attachment's mode to active-active.
Why it's wrong here
Active-active mode only affects availability, not routing preference.
✗
Set a lower cost on the Cloud Router interface for the preferred VLAN attachment.
Why it's wrong here
Cloud Router interfaces do not have a cost metric; path selection is BGP-based.
✓
Configure BGP MED values on the on-premises router for the prefixes advertised to the Cloud Router.
Why this is correct
MED influences the Cloud Router's path selection, giving preference to lower MED.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse influencing inbound vs. outbound traffic and incorrectly choose options that affect Cloud Router's outbound path selection (like route priorities or interface cost) instead of using BGP MED to influence the on-premises router's advertisement.
Detailed technical explanation
How to think about this question
BGP MED is a non-transitive optional attribute that is exchanged between AS peers to influence the decision process of the receiving AS when multiple paths exist. In Google Cloud, the Cloud Router receives MED values from on-premises routers and uses them in the BGP best-path selection algorithm (lower MED is preferred) for inbound traffic, but only if the paths are from the same neighboring AS. This is particularly useful in scenarios with multiple Partner Interconnect connections or multiple VLAN attachments to different on-premises locations, where asymmetric routing or suboptimal paths can occur without explicit MED tuning.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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 BGP MED values on the on-premises router for the prefixes advertised to the Cloud Router. — Option D is correct because BGP MED (Multi-Exit Discriminator) is the standard mechanism for influencing inbound traffic path selection when multiple connections exist between two autonomous systems. By setting a lower MED value on the on-premises router for prefixes advertised to the Cloud Router, the on-premises network can signal Google Cloud to prefer that specific VLAN attachment for traffic destined to the subnet, thereby correcting the suboptimal path.
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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