The correct configuration is to create one backend service and add two instance groups, one from each region. This works because a global external HTTP(S) load balancer is designed to operate as a single, multi-region frontend, requiring a single backend service that can span multiple regions to distribute traffic across all healthy backends. On the Google Professional Cloud Network Engineer exam, this tests your understanding that global load balancers use a unified backend service, not separate services per region—a common trap is thinking you need a backend service for each region. The load balancer’s anycast IP and Google’s global network automatically route each client to the closest healthy instance group, optimizing latency and providing regional failover. Memory tip: think “one service, many groups” to avoid splitting backends by region.
PCNE Practice Question: Designing, planning, and prototyping a GCP network
This PCNE practice question tests your understanding of designing, planning, and prototyping a gcp network. 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 company wants to deploy an HTTP application on Compute Engine instances in us-east1 and europe-west1, and use a global external HTTP(S) load balancer. How should they configure the backend?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create one backend service and add two instance groups, one from each region.
A global external HTTP(S) load balancer requires a single backend service that can span multiple regions. By adding one instance group from us-east1 and another from europe-west1 to the same backend service, the load balancer automatically routes traffic to the closest healthy backend based on the client's geographic location and the load balancer's anycast IP. This configuration leverages Google's global network infrastructure for optimal latency and failover.
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 regional load balancer in each region and use DNS round-robin.
Why it's wrong here
This is not global load balancing and may cause uneven distribution.
✓
Create one backend service and add two instance groups, one from each region.
Why this is correct
This allows the load balancer to distribute traffic globally.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create one backend service and add one instance group with instances in both regions.
Why it's wrong here
Instance groups are zonal; you cannot have instances from two regions in one group.
✗
Create two backend services, one per region, and attach to the same URL map.
Why it's wrong here
A single backend service can include multiple instance groups from different regions.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates mistakenly think instance groups can span multiple regions (Option C) or that multiple backend services are needed for multi-region deployments (Option D), when in fact a single backend service with multiple regional instance groups is the correct and simplest design for a global load balancer.
Detailed technical explanation
How to think about this question
The global external HTTP(S) load balancer uses a single anycast IP address (e.g., 34.96.0.0/16 range) that is announced from Google's edge points of presence worldwide. When a client connects, the load balancer's global frontend directs traffic to the closest healthy backend instance group based on the client's source IP and the load balancing algorithm (e.g., RING_HASH or LEAST_REQUEST). The backend service must be configured with a health check per instance group; if one region's instances become unhealthy, traffic is automatically redirected to the other region without any DNS changes.
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.
Designing, planning, and prototyping a GCP network — This question tests Designing, planning, and prototyping a GCP network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create one backend service and add two instance groups, one from each region. — A global external HTTP(S) load balancer requires a single backend service that can span multiple regions. By adding one instance group from us-east1 and another from europe-west1 to the same backend service, the load balancer automatically routes traffic to the closest healthy backend based on the client's geographic location and the load balancer's anycast IP. This configuration leverages Google's global network infrastructure for optimal latency and failover.
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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