- A
Create a single VLAN attachment, then use a shared VPC with two subnets. Configure one Cloud Router with two BGP sessions, one for each subnet.
Why wrong: Shared VPC does not solve the need for separate VPCs; also bandwidth is not isolated.
- B
Create one VLAN attachment with 1 Gbps capacity, attach it to both VPCs using a single Cloud Router with two BGP sessions.
Why wrong: A VLAN attachment cannot be shared across VPCs directly; each VPC requires its own attachment.
- C
Create two VLAN attachments on the same interconnect, each with 500 Mbps capacity. Configure a separate Cloud Router for each VPC, each with a BGP session on its respective VLAN attachment. Use BGP metrics for active/passive failover.
Correct. This meets bandwidth and HA requirements.
- D
Order two separate 1 Gbps Partner Interconnect connections, one for each VPC, and configure each with a single VLAN attachment.
Why wrong: Unnecessary cost; a single interconnect can support multiple VLAN attachments.
Quick Answer
The answer is to create two VLAN attachments on the same Partner Interconnect, each with 500 Mbps capacity, and configure separate Cloud Routers with BGP sessions for active/passive failover. This works because a single Partner Interconnect connection supports multiple VLAN attachments, each with its own dedicated bandwidth allocation, allowing you to split the 1 Gbps link into two 500 Mbps segments for separate VPCs. For high availability, you use BGP metrics like local preference on one Cloud Router to prefer its path, while the other remains passive, ensuring failover without needing a second physical connection. On the Google Professional Cloud Network Engineer exam, this tests your understanding that VLAN attachments are virtual interfaces that can carve bandwidth from a single interconnect, and the common trap is assuming you need two physical connections for HA or separate bandwidth. Remember the mnemonic: “One wire, two VLANs, BGP for the plan.”
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 deploying a hybrid cloud solution using Partner Interconnect. They have ordered a 1 Gbps connection from a partner at a colocation facility. The on-premises network uses a 10 Gbps link to the colo, and the partner provides a single 1 Gbps connection to Google Cloud. The company wants to connect two separate VPC networks in Google Cloud (production and development) to their on-premises network. Each VPC requires 500 Mbps of dedicated bandwidth. The company also needs high availability for the connection. What should they do?
Answer choices
Why each option matters
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 on the same interconnect, each with 500 Mbps capacity. Configure a separate Cloud Router for each VPC, each with a BGP session on its respective VLAN attachment. Use BGP metrics for active/passive failover.
Option C is correct because Partner Interconnect supports multiple VLAN attachments on a single connection, each with its own capacity allocation. By creating two VLAN attachments with 500 Mbps each, you can dedicate bandwidth to each VPC while meeting the 500 Mbps requirement. Using separate Cloud Routers with BGP sessions on each VLAN attachment and adjusting BGP metrics (e.g., local preference) allows active/passive failover for high availability, satisfying both the bandwidth and HA needs without requiring additional physical connections.
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 a single VLAN attachment, then use a shared VPC with two subnets. Configure one Cloud Router with two BGP sessions, one for each subnet.
Why it's wrong here
Shared VPC does not solve the need for separate VPCs; also bandwidth is not isolated.
- ✗
Create one VLAN attachment with 1 Gbps capacity, attach it to both VPCs using a single Cloud Router with two BGP sessions.
Why it's wrong here
A VLAN attachment cannot be shared across VPCs directly; each VPC requires its own attachment.
- ✓
Create two VLAN attachments on the same interconnect, each with 500 Mbps capacity. Configure a separate Cloud Router for each VPC, each with a BGP session on its respective VLAN attachment. Use BGP metrics for active/passive failover.
Why this is correct
Correct. This meets bandwidth and HA requirements.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Order two separate 1 Gbps Partner Interconnect connections, one for each VPC, and configure each with a single VLAN attachment.
Why it's wrong here
Unnecessary cost; a single interconnect can support multiple VLAN attachments.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a single VLAN attachment can serve multiple VPCs or that multiple physical connections are required for multiple VPCs, but Partner Interconnect allows multiple VLAN attachments on one connection, each dedicated to a different VPC with its own bandwidth and BGP session.
Detailed technical explanation
How to think about this question
Partner Interconnect uses VLAN attachments (also called interconnect attachments) that map to a specific VLAN ID and are associated with a Cloud Router for BGP peering. Each VLAN attachment can have its own capacity (in multiples of 50 Mbps up to 10 Gbps) and is independent, allowing bandwidth guarantees per VPC. For active/passive failover, you can set BGP local preference (e.g., 100 on primary, 50 on secondary) on the Cloud Routers to prefer one path; if the primary fails, the secondary BGP session takes over. This design ensures that even if the single physical connection is shared, logical separation and HA are maintained.
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.
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Implementing hybrid interconnectivity — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
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: Create two VLAN attachments on the same interconnect, each with 500 Mbps capacity. Configure a separate Cloud Router for each VPC, each with a BGP session on its respective VLAN attachment. Use BGP metrics for active/passive failover. — Option C is correct because Partner Interconnect supports multiple VLAN attachments on a single connection, each with its own capacity allocation. By creating two VLAN attachments with 500 Mbps each, you can dedicate bandwidth to each VPC while meeting the 500 Mbps requirement. Using separate Cloud Routers with BGP sessions on each VLAN attachment and adjusting BGP metrics (e.g., local preference) allows active/passive failover for high availability, satisfying both the bandwidth and HA needs without requiring additional physical connections.
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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Last reviewed: Jun 11, 2026
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.
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