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Optimizing service performance

Practise Google Professional Cloud DevOps Engineer Optimizing service performance practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.

109 questions30 easy43 medium36 hard

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What to know about Optimizing service performance

Optimizing service performance questions test whether you can apply the concept in context, not just recognise a definition.

How the topic appears in realistic exam-style scenarios.

Which detail in the question changes the correct answer.

How to eliminate plausible but wrong options.

How to connect the question back to the wider exam objective.

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Common Optimizing service performance exam traps

  • Answering from memory before reading the full scenario.
  • Missing a constraint such as cost, availability, security, scope or command context.
  • Choosing a broad answer when the question asks for the most specific fix.
  • Ignoring why the wrong options are tempting.

Question index

All Optimizing service performance questions (109)

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1

A company serves static content using a global HTTP(S) load balancer with Cloud CDN. They want to maximize the cache hit ratio. Which two actions should they take?

Easy
2

A DevOps team wants to autoscale a GKE Deployment based on a custom metric exposed by the application. The metric is available via an HTTP endpoint. Which approach should they use to integrate this metric with the Horizontal Pod Autoscaler (HPA)?

Medium
3

A latency-sensitive web application uses Cloud CDN. What configuration change would most directly reduce cache miss rates?

Easy
4

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?

Hard
5

A DevOps team wants to serve static content from a Cloud Storage bucket with low latency globally. They also need TLS termination. Which load balancer type should they use?

Easy
6

Which tool can be used to capture and analyze latency spikes in a distributed application?

Hard
7

A team notices that Cloud SQL read replicas are not handling read traffic efficiently, causing high latency for read-heavy queries. What is the best approach to improve read performance?

Medium
8

Which Cloud Run setting controls the maximum number of requests a container can handle concurrently?

Medium
9

A team uses Cloud Spanner for a global application. Query performance degrades as data grows. They notice that most queries filter on a column 'customer_id' but the primary key is a UUID. What is the best approach to optimize performance?

Hard
10

Your team deploys a microservice on Google Kubernetes Engine (GKE) that serves an API with low latency requirements. Users report that the API occasionally times out during peak hours. You check the GKE metrics and see that CPU utilization is below 50% but memory is near 100% on the nodes. What is the most likely cause and what should you do?

Medium
11

Refer to the exhibit. The team observes that some requests are fast while others are slow. Both requests have identical payload and response. What is the most likely cause of the latency difference?

Hard
12

A company's Cloud SQL for PostgreSQL instance is experiencing performance degradation. They observe a high number of idle connections and slow transaction commit times. Which combination of actions will most effectively address this issue?

Hard
13

A web application frequently reads the same set of reference data from Cloud SQL. This causes high database load and slow responses. Which design change would most improve performance?

Medium
14

Which service is commonly used for time-series data and real-time analytics?

Easy
15

Refer to the exhibit. After applying the shown firewall rule, users report increased latency to a web application. What is the most likely cause?

Hard
16

A batch data processing job on Cloud Dataflow is running slower than expected. Which action will most directly increase throughput?

Easy
17

Refer to the exhibit. A team is troubleshooting a pod crash loop. Based on the exhibit, which infrastructure change should be prioritized to resolve the issue and optimize service performance?

Hard
18

A Cloud Spanner database is experiencing slow query performance. Which approach should be taken to optimize read performance without compromising consistency?

Medium
19

An organization uses Cloud CDN with an HTTP(S) Load Balancer to serve static content. They observe that cache hit ratio is lower than expected. The content is immutable and has long Cache-Control headers. What is the most likely cause?

Hard
20

A company uses Cloud SQL for their transactional database. They are experiencing slow read performance. Which THREE actions can improve read throughput? (Choose three.)

Medium
21

A team is running a stateful application on Compute Engine with high disk I/O. They want to optimize disk performance. Which TWO actions should they take? (Choose two.)

Medium
22

A backend service receives bursts of requests that cause timeouts. The team wants to smooth out the load while ensuring all requests are processed eventually. Which strategy should they use?

Easy
23

A team deploys a microservice on Google Kubernetes Engine (GKE) that processes user uploads. The service latency has increased over time. Monitoring shows that CPU utilization is low, but memory usage is high and garbage collection (GC) pauses are frequent. Which action is most likely to reduce latency?

Medium
24

Which THREE approaches can help reduce egress costs while improving performance for a multi-region application using Cloud Load Balancing? (Choose 3)

Hard
25

Refer to the exhibit. A DevOps engineer notices that instance-1 runs on older CPU platform. The application is sensitive to CPU features that are only available on Skylake or newer. Which action should be taken to optimize performance?

Medium
26

A gaming company runs a real-time multiplayer server on GKE. They want to minimize latency between players worldwide. Which approach should they use?

Medium
27

A DevOps team wants to optimize the performance of a Cloud Run service that experiences sporadic traffic. Which TWO strategies should they implement?

Easy
28

A team wants to simulate real-world user traffic to identify performance bottlenecks before a launch. Which tool should they use to generate load from multiple regions?

Medium
29

A team is troubleshooting a slow response time on an App Engine standard environment application. The application uses Cloud SQL as its database. Which TWO actions should the team take to identify the bottleneck?

Medium
30

A company is using Cloud CDN to deliver static content globally. Some users in Asia report slow load times. Which configuration change would most likely improve performance for these users?

Easy
31

A data engineering team runs frequent aggregation queries on a large BigQuery table. Query performance is slow and costs are high. Which optimization technique would best improve performance and reduce cost?

Hard
32

You are using Memorystore for Redis as a cache for a high-traffic web application. You observe that cache hit ratio is low, causing high database load. What is the most effective way to improve cache hit ratio?

Medium
33

Your application uses Cloud SQL for MySQL and you notice that read replica lag is increasing. Which action would most likely reduce replica lag?

Easy
34

Your team has deployed a microservices application on Google Kubernetes Engine (GKE). You notice that one service has high latency during peak hours. The service is CPU-bound and uses a HorizontalPodAutoscaler (HPA) based on CPU utilization. What is the most likely cause of the latency?

Medium
35

A company runs a high-traffic web application on GKE. Which three practices can help optimize performance under load? (Select THREE.)

Hard
36

Which TWO actions should a DevOps engineer take to reduce latency for a global user base accessing a web application hosted on Compute Engine?

Hard
37

Refer to the exhibit. An App Engine application returns 504 errors. The application calls an external API and processes the result. Which change is most likely to resolve the errors?

Medium
38

Match each monitoring concept to its purpose.

Medium
39

Your team is running a high-traffic web application on Google Kubernetes Engine (GKE) and has configured Horizontal Pod Autoscaling (HPA) based on CPU utilization. Recently, the application experienced intermittent latency spikes during traffic bursts. You suspect that the HPA is not scaling quickly enough. Which TWO actions would most effectively improve the autoscaling responsiveness?

Medium
40

A DevOps team wants to optimize resource utilization for their GKE deployment. Which built-in Kubernetes resource can automatically adjust CPU and memory requests based on historical usage?

Medium
41

A Cloud Run service experiences high cold start latency. The team has already set min-instances to 1. Which additional optimization can further reduce cold start impact?

Hard
42

A company deploys a microservices application on Google Kubernetes Engine (GKE). They notice increased latency during peak hours. The application uses a Cloud SQL database for state. The team wants to optimize service performance. What should they do first?

Medium
43

An e-commerce platform uses Cloud Load Balancing with backend services running on Compute Engine managed instance groups. During Black Friday sales, the application experiences high latency and some 503 errors. The team uses autoscaling based on average CPU utilization, but scaling is too slow—Cloud Monitoring shows CPU rises to 90% before new instances are added. The team needs to reduce latency and eliminate 503 errors. What should they do?

Medium
44

A company runs a batch processing pipeline on Dataflow that reads from Pub/Sub and writes to BigQuery. The pipeline is falling behind due to high volume, and messages are backing up in Pub/Sub. Autoscaling is enabled and workers are running but utilization is only 30%. The streaming engine is off. What should the engineer do to increase throughput?

Hard
45

A DevOps team is troubleshooting a web application that shows high latency during peak hours. The application runs on Google Kubernetes Engine (GKE). They want to identify which specific API calls are causing the delay. Which Google Cloud tool should they use?

Easy
46

A Cloud Run service experiences high latency during cold starts. The service is memory-intensive. Which configuration change will most effectively reduce cold start latency?

Hard
47

A company runs a web application on Compute Engine behind a regional HTTP Load Balancer. Users report slow page load times during peak hours. CPU utilization on instances is under 60%, but network egress is near the instance's bandwidth limit. Which action should the engineer take?

Easy
48

Which THREE factors should you consider when designing a Cloud Run service for optimal performance under unpredictable traffic patterns? (Choose 3)

Hard
49

A team notices that a Cloud Run service occasionally has high latency. They suspect a memory leak or excessive CPU usage. Which tool should they use to identify the bottleneck during those periods?

Medium
50

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?

Easy
51

Which THREE strategies can reduce API latency in Apigee?

Hard
52

Which service should be used to monitor the health of HTTP endpoints from multiple locations?

Easy
53

An application running on GKE experiences high latency during traffic spikes. The team wants to scale pods based on request latency. Which metric should they use in the HorizontalPodAutoscaler?

Easy
54

Refer to the exhibit. A DevOps engineer observes that a GKE cluster's node performance is degraded during high I/O workloads. Based on the exhibit, which change would most likely improve disk I/O performance?

Medium
55

A company runs a microservices architecture on GKE and notices high network latency between services. Which THREE actions can improve inter-service communication performance?

Hard
56

A company runs a stateful workload on Compute Engine VMs with persistent disks. They observe that disk I/O latency spikes periodically. The workload is sensitive to latency. What should they do to improve performance?

Easy
57

A team wants to optimize a batch processing job that is CPU-bound. Which Compute Engine machine family should they use?

Hard
58

A team is using Cloud Run for a containerized application. They notice that requests have high latency due to cold starts. Which configuration change would most effectively reduce cold start latency?

Medium
59

An application running on GKE experiences high tail latency. The team is optimizing performance. Which THREE techniques should they consider? (Choose three.)

Hard
60

An application running on App Engine standard environment has high instance startup latency, leading to slow first requests. What is the most effective configuration change to reduce cold starts?

Easy
61

You are using Cloud CDN with an external HTTPS load balancer. Users in Asia report slow load times for static assets. The origin is in us-central1. What should you do to improve performance?

Hard
62

Refer to the exhibit. A team uses these Compute Engine instances to run a batch processing job. The job frequently gets killed on instance-3. What is the most likely cause?

Hard
63

A financial services company runs a real-time trading application on GKE with 10 microservices. The application uses Cloud Spanner as the database. Recently, the team noticed increased latency during peak trading hours. Cloud Monitoring shows high CPU utilization on the Spanner nodes (averaging 80%) and increased locking contention. The team has already added secondary indexes and tuned queries. The application's latency budget is 50ms for writes and 20ms for reads. The team must reduce latency while maintaining strong consistency and meeting the budget. What should they do?

Hard
64

A DevOps team is investigating performance issues in their GKE cluster. They want to use Cloud Profiler to identify the bottleneck. Which three steps are required to start profiling? (Select THREE)

Medium
65

A DevOps team uses Cloud Run for a containerized application that processes real-time financial data. The service has a concurrency setting of 80, and instances are scaled based on CPU usage. During market volatility, the service experiences high latency and some requests timeout. Cloud Monitoring shows that the average CPU utilization is 40%, but the instance count spikes to the maximum allowed. What is the most likely cause?

Medium
66

Refer to the exhibit. A team runs a batch processing job on these instances. The job is CPU-bound and can tolerate interruptions. Which instance is the most cost-effective for this workload?

Easy
67

A team uses Cloud Load Balancing with backend NEGs. Users report intermittent high latency. How should they diagnose the root cause effectively?

Medium
68

Refer to the exhibit. The team wants to reduce the service's p50 latency from 2 seconds to under 500ms. Which optimization would have the most impact?

Hard
69

A company notices increased latency for their web application running on Compute Engine. They suspect a database bottleneck. Which Google Cloud service should they use to identify slow queries?

Easy
70

A company has a stateful application deployed on a GKE cluster with stateful sets using persistent volumes. The application is experiencing higher than expected latency for write operations. The team uses SSDs for persistent disks. Cloud Monitoring shows high disk queue depth on the nodes where the stateful pods are scheduled. Which of the following is the most effective optimization?

Medium
71

A team is optimizing the performance of their application running on Cloud Run. They want to reduce cold starts. Which two actions would help? (Select TWO)

Medium
72

You are a DevOps engineer at a media streaming company. Your application runs on Google Kubernetes Engine (GKE) and serves video content to users worldwide. The application uses a microservices architecture with a frontend service that handles user requests and a backend transcoding service that converts video files. Recently, you noticed that the transcoding service is causing performance bottlenecks during peak hours, leading to increased latency for users. You have enabled Cloud Monitoring and Cloud Trace and observed that the transcoding service's CPU utilization is consistently above 90% during peak times, and the queue of video transcoding tasks is growing. The current deployment has 5 replicas of the transcoding service with no autoscaling. You need to optimize the performance of the transcoding service to reduce latency. Your company has a limited budget and wants to minimize costs. What should you do?

Easy
73

An organization uses Cloud Armor to protect their web application. After enabling the service, they notice increased latency on some requests. Which Cloud Armor feature is most likely causing this?

Medium
74

Which storage class provides the lowest cost for data accessed less than once a year?

Medium
75

A team is running a stateful application on Compute Engine VMs. They notice that the application performance degrades over time as the disk fills up. They want to proactively alert before performance degrades. Which metric should they monitor?

Medium
76

A DevOps engineer is optimizing a Cloud Run service that experiences cold starts. The service is written in Python and uses several large libraries. Which change is most effective to reduce cold start latency?

Easy
77

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?

Hard
78

A company uses Cloud Monitoring to set up alerting for their production system. They want to reduce alert fatigue while ensuring critical issues are caught quickly. Which two strategies should they implement? (Select TWO)

Hard
79

A DevOps team is using Cloud Build to build and push container images. The build times have increased significantly. They suspect that the build cache is not being used effectively. Which build configuration change would likely improve cache usage?

Hard
80

A company is migrating a batch processing workload to Google Cloud. The workload is CPU-intensive and runs for a few hours each day. Which Compute Engine machine family should they choose to optimize performance and cost?

Medium
81

A company runs a production web application on Google Compute Engine behind an HTTP(S) load balancer. The application is deployed across multiple managed instance groups in three regions (us-east1, europe-west1, asia-east1). Recently, users report slow page load times. Monitoring shows that CPU utilization on instances is consistently low (around 30%) but memory usage is high (over 80%). The application uses a self-managed in-memory cache per instance to store session data and frequently accessed objects. The team is considering adding more instances to the instance groups to distribute the load. However, they notice that the load balancer's latency is spiking and the cache hit ratio is low. What is the most likely issue and what should the engineer do?

Medium
82

A web application experiences high latency during peak hours. Which TWO actions should the team take to optimize performance?

Medium
83

Arrange the steps to implement a canary deployment for a Cloud Run service.

Medium
84

You are designing a globally distributed application using Cloud Spanner. The application has a write-heavy workload. You notice that write latency increases as the number of nodes increases. What is the most likely cause?

Hard
85

Your GKE cluster runs a batch job that processes large files from Cloud Storage. The job uses CPUs inefficiently, with low utilization. You want to reduce cost while maintaining throughput. Which approach should you take?

Medium
86

Which TWO actions can reduce startup latency for a Cloud Run service?

Easy
87

Refer to the exhibit. A payment microservice on GKE logs frequent 'connection closed' errors. The service connects to a backend database. Which approach is most effective to reduce these errors?

Hard
88

A company serves static assets (images, CSS) to global users. Users in distant regions experience slow load times. Which service should they use to optimize delivery?

Easy
89

You created the above alert policy to detect high CPU utilization in your GKE cluster. However, you are receiving too many false positive alerts. What is the most likely reason?

Hard
90

Which TWO metrics from Cloud Monitoring would best indicate that a GKE workload is experiencing CPU throttling due to a resource quota? (Choose 2)

Medium
91

Refer to the exhibit. A GKE node shows MemoryPressure condition. What should the team do to improve performance of pods scheduled on this node?

Easy
92

A company runs a microservices application on GKE. The checkout service has high tail latency. Using Cloud Profiler, the team finds that most time is spent in database queries. Which action should they take to improve performance?

Medium
93

A company wants to reduce the response time of a globally distributed web application. Which Google Cloud service can cache static content at edge locations to improve performance?

Easy
94

An application on GKE frequently reads the same data from a Cloud Storage bucket. The data changes rarely. Which solution will best improve read performance and reduce costs?

Medium
95

A startup runs a mobile app backend on App Engine standard environment. They recently added new features, and the app's response time increased significantly. The team suspects instance startup time is causing cold starts for new users. They have already reduced code size and enabled warmup requests. What is the best next step to improve performance?

Easy
96

Refer to the exhibit. What does the alert condition indicate?

Easy
97

A web application serves static assets (images, CSS, JavaScript) from Compute Engine instances. Users in different geographic regions report slow page loads. Which Google Cloud service can be used to improve performance for these users?

Easy
98

A company runs a microservices architecture on GKE with Istio service mesh. They observe that service-to-service latency has increased after enabling mTLS. What is the most likely cause?

Hard
99

A team deploys a Cloud Function that processes user requests. They notice cold starts cause high latency for the first request after a period of inactivity. What is the most effective way to reduce cold starts?

Easy
100

A company runs a stateful workload on Compute Engine with local SSDs. They need to improve disk I/O performance without changing the instance type. Which THREE actions should they take?

Hard
101

A company is transferring large datasets from on-premises to Google Cloud using a VPN. They notice high latency due to packet loss. What is the most effective way to improve throughput?

Hard
102

A DevOps team wants to monitor the performance of a Cloud SQL database. Which two metrics should they track? (Select TWO.)

Easy
103

A Cloud Run service is experiencing increased cold start latency. The service is written in Python and uses several large dependencies. Which action would most effectively reduce cold start latency?

Easy
104

A large stateful service running on Compute Engine experiences variable performance due to CPU throttling from noisy neighbors. Which solution provides the most consistent performance?

Hard
105

Which TWO actions can reduce tail latency in a microservices architecture deployed on GKE? (Choose 2)

Medium
106

Which TWO practices should be implemented to optimize query performance in Cloud Spanner?

Medium
107

A company runs a critical application on Compute Engine instances behind a TCP/UDP Network Load Balancer. They notice intermittent high latency for a subset of users. The application logs show no errors, and instance CPU is below 50%. Which next step is most effective to diagnose the latency?

Hard
108

A media streaming service uses Cloud Storage to store video files and serves them via Cloud CDN. Users in Asia report buffering issues. The team notices that the cache hit ratio is low in that region. The origin is a single Cloud Storage bucket in us-central1. Which set of actions would best improve performance for Asian users?

Hard
109

A team uses Spanner for a global database. They notice increased read latency and high CPU utilization on some nodes. The workload is read-heavy with occasional writes. Which action is most likely to improve performance?

Medium

Frequently asked questions

What does the Optimizing service performance domain cover on the PCDOE exam?
Optimizing service performance questions test whether you can apply the concept in context, not just recognise a definition.
How many questions are in this domain?
This page lists all 109 Optimizing service performance questions in the PCDOE question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
What is the best way to practise this domain?
Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
Can I practise only Optimizing service performance questions?
Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.
Google Professional Cloud DevOps Engineer PCDOE Optimizing service performance Practice Questions