The correct answer is to create two VLAN attachments, one for each region, over the same interconnect. This works because a single Partner Interconnect connection supports multiple VLAN attachments, each of which can be associated with a different Cloud Router in a different region, allowing traffic from the on-premises network to reach VPCs in both us-east1 and europe-west1 over the same physical link. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding that VLAN attachments are regional resources, not global, and that a single interconnect can serve multiple regions by adding separate attachments. A common trap is assuming you need a separate interconnect per region, which would be costly and unnecessary. Memory tip: think of the interconnect as a highway and each VLAN attachment as an off-ramp to a different city—one highway, many off-ramps.
PCNE Configuring network services Practice Question
This PCNE practice question tests your understanding of configuring network services. 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.
A large enterprise is migrating to Google Cloud and needs to establish connectivity between on-premises and VPCs in two different regions (us-east1 and europe-west1). They have a single Partner Interconnect connection at a co-location facility in New York. They want to use the same interconnect for both regions. Which configuration should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create two VLAN attachments, one for each region, over the same interconnect
A is correct because a single Partner Interconnect connection can support multiple VLAN attachments, each associated with a different region. By creating two VLAN attachments over the same interconnect—one for us-east1 and one for europe-west1—the enterprise can route traffic from the on-premises network to both VPCs using the same physical link, leveraging Google Cloud's support for multiple VLAN attachments per interconnect.
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.
✓
Create two VLAN attachments, one for each region, over the same interconnect
Why this is correct
VLAN attachments are regional; multiple can share same interconnect.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create one VLAN attachment and attach it to both VPCs
Why it's wrong here
A VLAN attachment can only be attached to one VPC.
✗
Use HA VPN over the interconnect to connect both regions
Why it's wrong here
HA VPN is for Cloud VPN, not using the interconnect directly.
✗
Create two Cloud VPN tunnels from on-prem to each VPC
Why it's wrong here
Does not use the interconnect; unnecessary overhead.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a single VLAN attachment can serve multiple regions, but in Google Cloud, VLAN attachments are regional resources and cannot be shared across regions.
Detailed technical explanation
How to think about this question
Each VLAN attachment corresponds to a specific Cloud Router and region, and the interconnect's underlying L2 connection is partitioned using 802.1Q VLAN tags. The on-premises router must be configured with two subinterfaces, each with a unique VLAN ID, to terminate the two VLAN attachments; Google Cloud then uses BGP sessions over each attachment to exchange routes for the respective VPCs. In a real-world scenario, if the enterprise needs to support traffic engineering or failover, they could also enable Cloud Router's graceful restart or use multiple BGP sessions per attachment.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Configuring network services — This question tests Configuring network services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create two VLAN attachments, one for each region, over the same interconnect — A is correct because a single Partner Interconnect connection can support multiple VLAN attachments, each associated with a different region. By creating two VLAN attachments over the same interconnect—one for us-east1 and one for europe-west1—the enterprise can route traffic from the on-premises network to both VPCs using the same physical link, leveraging Google Cloud's support for multiple VLAN attachments per interconnect.
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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This PCNE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCNE exam.
Question Discussion
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