The answer is that Cloud CDN does not have edge caches in Asia, so requests from Asian users are served from the nearest available edge location, often in the western United States or Australia, causing high latency. Even with a 95% global cache hit ratio, the physical distance from Asia to those edge nodes dramatically increases round-trip time, explaining the 5-10 second load times for product images. On the Google Professional Cloud DevOps Engineer exam, this scenario tests your understanding that Cloud CDN’s global cache hit ratio can be misleading—it aggregates all regions, masking regional gaps in edge presence. A common trap is assuming a high global hit ratio means low latency everywhere, but without local edge caches, distance still dominates. Remember: cache hits reduce origin trips, but they don’t shrink the speed of light. For memory, think “no edge in Asia means no speed in Asia.”
PCDOE Optimizing service performance Practice Question
This PCDOE practice question tests your understanding of optimizing service performance. 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.
Your company runs a multi-region e-commerce platform on Google Kubernetes Engine (GKE) with services in us-central1 and europe-west1. The application uses a global external HTTP(S) load balancer with Cloud CDN for static assets. Recently, users in Asia report that product images take 5-10 seconds to load, while users in the US and Europe experience sub-second load times. You check the Cloud CDN cache hit ratio and see it is 95% globally. You also notice that the images are served from a backend bucket in us-central1. The load balancer uses the default routing configuration. Your team has implemented client-side caching with Cache-Control headers set to public, max-age=3600. What is the most likely cause of the high latency for Asian users?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cloud CDN does not have edge caches in Asia, so requests are served from the nearest available edge location, which may be far from users.
Option C is correct because Cloud CDN does not have edge caches in Asia; the nearest edge locations for Asian users are in the western United States (e.g., Los Angeles) or possibly Australia, resulting in higher latency. Even with a 95% global cache hit ratio, the physical distance from Asia to the serving edge increases round-trip time (RTT) significantly, causing 5-10 second load times. The default routing configuration of the global external HTTP(S) load balancer does not automatically optimize for regional cache presence.
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.
✗
The load balancer is not using premium tier networking, so traffic from Asia takes a longer path.
Why it's wrong here
Premium tier could help but the issue is cache availability, not network path.
✗
Client-side caching with max-age=3600 is too short, causing frequent revalidation.
Why it's wrong here
Client-side caching does not affect server latency.
✓
Cloud CDN does not have edge caches in Asia, so requests are served from the nearest available edge location, which may be far from users.
Why this is correct
Cloud CDN edge locations in Asia may be limited; first request latency is high due to cache miss.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The cache hit ratio is too low for Asian users due to different traffic patterns.
Why it's wrong here
Global cache hit ratio is 95%, so cache is effective.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a high global cache hit ratio guarantees low latency for all users, ignoring the impact of geographic distance between edge caches and end users.
Detailed technical explanation
How to think about this question
Cloud CDN edge caches are deployed in Google's points of presence (PoPs) worldwide, but as of this writing, there are no PoPs in mainland China, India, or Southeast Asia; the closest PoPs are in Taiwan, Hong Kong, Japan, and Australia. When a request from Asia hits a cache miss, the origin pull goes to the backend bucket in us-central1, adding cross-Pacific latency. Even on a cache hit, the response must travel from a US West Coast PoP to the Asian user, which can add 150-200ms RTT, and with large images (e.g., 2-5 MB) over TCP congestion control, this can balloon to several seconds.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
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: Cloud CDN does not have edge caches in Asia, so requests are served from the nearest available edge location, which may be far from users. — Option C is correct because Cloud CDN does not have edge caches in Asia; the nearest edge locations for Asian users are in the western United States (e.g., Los Angeles) or possibly Australia, resulting in higher latency. Even with a 95% global cache hit ratio, the physical distance from Asia to the serving edge increases round-trip time (RTT) significantly, causing 5-10 second load times. The default routing configuration of the global external HTTP(S) load balancer does not automatically optimize for regional cache presence.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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