- A
Switch to a regional load balancer to route traffic more efficiently.
Why wrong: A global load balancer is already in use and is appropriate for global traffic; switching to regional would not help European users.
- B
Configure a multi-regional Cloud CDN and enable cache warming for popular content.
Why wrong: Cloud CDN is already enabled; cache warming might help cache hit ratio but not latency for uncached requests.
- C
Add Compute Engine instances in a European region (e.g., europe-west1) and add them to the load balancer's backend.
Adding instances in Europe reduces the distance between users and servers, lowering latency.
- D
Increase the machine type of existing instances to improve processing speed.
Why wrong: Instance size affects throughput but not network latency; the bottleneck is distance.
Quick Answer
The answer is to add Compute Engine instances in a European region, such as europe-west1, and add them to the load balancer's backend. This is correct because even with Cloud CDN enabled, cache misses force a round trip to the origin server; placing a backend in Europe physically shortens that path, directly reducing latency for European users. The global HTTP(S) Load Balancer automatically routes requests to the closest healthy backend, so this action leverages geographic proximity to improve performance. On the Google Professional Cloud DevOps Engineer exam, this tests your understanding that Cloud CDN alone isn't enough for dynamic or uncached content—the origin location still matters. A common trap is assuming CDN fully solves latency, but the backend must also be close to the user base. Memory tip: think "CDN for cache, backend for origin"—both must be near your users to minimize round trips.
PCDOE Optimizing service performance Practice Question
This PCDOE practice question tests your understanding of optimizing service performance. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Your company runs a web application on Compute Engine behind a global HTTP(S) Load Balancer. You want to improve performance for users in Europe. You have already enabled Cloud CDN. What is the next best action to reduce latency?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Add Compute Engine instances in a European region (e.g., europe-west1) and add them to the load balancer's backend.
Adding Compute Engine instances in a European region (e.g., europe-west1) and adding them to the load balancer's backend reduces latency by bringing the origin server physically closer to European users. Even with Cloud CDN enabled, cache misses still require a round trip to the backend; having a backend in Europe minimizes that distance. The global HTTP(S) Load Balancer automatically routes requests to the closest healthy backend, so this directly improves performance for users in Europe.
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.
- ✗
Switch to a regional load balancer to route traffic more efficiently.
Why it's wrong here
A global load balancer is already in use and is appropriate for global traffic; switching to regional would not help European users.
- ✗
Configure a multi-regional Cloud CDN and enable cache warming for popular content.
Why it's wrong here
Cloud CDN is already enabled; cache warming might help cache hit ratio but not latency for uncached requests.
- ✓
Add Compute Engine instances in a European region (e.g., europe-west1) and add them to the load balancer's backend.
Why this is correct
Adding instances in Europe reduces the distance between users and servers, lowering latency.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the machine type of existing instances to improve processing speed.
Why it's wrong here
Instance size affects throughput but not network latency; the bottleneck is distance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume Cloud CDN alone solves all latency issues, forgetting that cache misses still require backend proximity, and that the global load balancer already supports multi-region backends without needing to switch to a regional load balancer.
Detailed technical explanation
How to think about this question
The global HTTP(S) Load Balancer uses anycast IP addresses and Google's global network to route traffic to the nearest healthy backend. When a cache miss occurs, Cloud CDN fetches content from the origin backend; if that backend is only in us-central1, a user in Europe experiences a transatlantic round trip of ~100-150 ms. Adding a backend in europe-west1 reduces that to ~10-30 ms. The load balancer's backend service supports multi-region instance groups, and health checks ensure traffic is only sent to healthy backends.
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.
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Optimizing service performance — study guide chapter
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FAQ
Questions learners often ask
What does this PCDOE question test?
Optimizing service performance — This question tests Optimizing service performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add Compute Engine instances in a European region (e.g., europe-west1) and add them to the load balancer's backend. — Adding Compute Engine instances in a European region (e.g., europe-west1) and adding them to the load balancer's backend reduces latency by bringing the origin server physically closer to European users. Even with Cloud CDN enabled, cache misses still require a round trip to the backend; having a backend in Europe minimizes that distance. The global HTTP(S) Load Balancer automatically routes requests to the closest healthy backend, so this directly improves performance for users in Europe.
What should I do if I get this PCDOE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
This PCDOE 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 PCDOE exam.
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