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.
A microservices application on GKE with Istio service mesh experienced performance degradation after a recent update. Which optimization technique is most effective for improving inter-service communication performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable gRPC for inter-service communication
Option D is correct because gRPC uses HTTP/2 as its transport protocol, which enables multiplexed streams over a single TCP connection, reducing latency and improving throughput for inter-service communication. In a GKE environment with Istio, gRPC also leverages Istio's native support for HTTP/2-based traffic, allowing efficient load balancing and connection reuse. This directly addresses performance degradation caused by chatty or high-frequency service calls.
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.
✗
Increase Istio sidecar resource limits
Why it's wrong here
While sidecar resources may be a bottleneck, upgrading to gRPC provides a more efficient protocol, directly improving performance.
✗
Implement request collapsing to merge identical requests
Why it's wrong here
Request collapsing is a specific optimization for certain patterns, not a general inter-service communication improvement.
✗
Use Istio traffic mirroring to offload requests
Why it's wrong here
Traffic mirroring duplicates requests for testing, not for improving production performance.
✓
Enable gRPC for inter-service communication
Why this is correct
gRPC leverages HTTP/2 and binary serialization, reducing overhead and latency compared to JSON-based REST.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that increasing resources (Option A) or adding caching (Option B) is the primary fix for performance issues, when the real bottleneck is often the communication protocol itself, especially in service mesh environments where gRPC is the recommended approach.
Detailed technical explanation
How to think about this question
gRPC uses Protocol Buffers for serialization, which is more compact and faster than JSON, and HTTP/2's multiplexing eliminates head-of-line blocking seen in HTTP/1.1. In Istio, sidecar proxies (Envoy) natively support HTTP/2 and gRPC, enabling advanced load balancing like least-request and connection pooling. A real-world scenario is a microservice with frequent small RPCs where switching from REST/JSON to gRPC reduced p99 latency by 40% due to reduced serialization overhead and connection reuse.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: Enable gRPC for inter-service communication — Option D is correct because gRPC uses HTTP/2 as its transport protocol, which enables multiplexed streams over a single TCP connection, reducing latency and improving throughput for inter-service communication. In a GKE environment with Istio, gRPC also leverages Istio's native support for HTTP/2-based traffic, allowing efficient load balancing and connection reuse. This directly addresses performance degradation caused by chatty or high-frequency service calls.
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.
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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