How to Configure VLAN Attachments for Maximum HA Diversity?

PCNE By islever Editorial Last updated

Short answer

D Build two VLAN attachments from each Dedicated Interconnect: one connecting to the Cloud Router in us-east1, and one connecting to the Cloud Router in us-west1.

Question

Your company is moving to a hybrid cloud environment and needs to connect two on-premises data centers to Google Cloud. Your company has opted for no service level agreement (SLA) on the Dedicated Interconnect ports. You set up a single Dedicated Interconnect to connect each on-premises data center to Google Cloud: one Dedicated Interconnect in us-east1 and another Dedicated Interconnect in us-west1. You also configured a Cloud Router for each Dedicated Interconnect in each respective region. You now need to configure the Interconnect attachments to provide as much high availability diversity as possible based on this design. What should you do?
  1. Build one VLAN attachment from each Dedicated Interconnect corresponding to the Cloud Router in that region.
  2. Build one VLAN attachment from each Dedicated Interconnect corresponding to the Cloud Router in that region.
  3. Build two VLAN attachments from each Dedicated Interconnect: one connecting to the Cloud Router in us-east1, and one connecting to the Cloud Router in us-west1.
  4. Build two VLAN attachments from each Dedicated Interconnect: one connecting to the Cloud Router in us-east1, and one connecting to the Cloud Router in us-west1. Correct Answer

Key Takeaways

This question tests knowledge of Google Cloud Interconnect attachment scalability and cross-region routing design, while the common trap is assuming a strict one-to-one mapping between physical interconnects and regional attachments limits fault tolerance.

Configuring multiple VLAN attachments over Dedicated Interconnects maximizes high availability diversity when connecting on-premises data centers to multi-region Google Cloud environments. The community unanimously agrees that creating two VLAN attachments per interconnect to span regional Cloud Routers is the optimal architectural approach.

Common mistake: Candidates often select the single-attachment option because it appears simpler to configure, but it creates a critical single point of failure by restricting all traffic to one region instead of leveraging cross-region redundancy.

Expert Analysis

Why the Answer Is Correct

Creating two VLAN attachments per Dedicated Interconnect allows you to logically segment traffic and associate each attachment with a Cloud Router in a different region. This design distributes workloads across us-east1 and us-west1, ensuring that a regional outage does not sever the entire hybrid connection. Google Cloud officially supports multiple VLAN attachments over a single physical Dedicated Interconnect to enable precise traffic engineering and geographic diversity.

Why the Other Options Are Wrong

Selecting a single VLAN attachment per interconnect restricts connectivity to only one region, directly contradicting the goal of maximizing high availability diversity. While options A and B appear identical in the prompt, they both represent a flawed one-to-one mapping that increases latency and eliminates cross-region failover capabilities. Option C mirrors the correct logic but is functionally redundant in this context, making D the standard best-practice configuration.

Community Comment Notes

All highly rated comments explicitly validate option D as the correct answer. Contributors emphasize that this configuration enables a global VPC architecture and properly utilizes multiple VLAN attachments for optimal redundancy [Comment 1]. The discussion consistently highlights that following Google's hybrid network best practices prevents unnecessary single points of failure.

Official Reference

These links open the official vendor documentation in a new tab.

Exam Strategy

When evaluating hybrid cloud connectivity questions, always prioritize logical segmentation over physical port limitations to identify the most resilient path. Remember that cloud providers typically allow multiple virtual attachments over a single physical circuit to facilitate cross-region redundancy and advanced traffic steering.

Community Votes

D
100%

100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

  1. b0b25 👍 1 Answered D
    D is the best practice enable global VPC and allow two vlan attachments
  2. RKS_2021 👍 1 Answered D
    D is correct.
  3. 09bd94b 👍 1 Answered D
    D is correct

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