PCD Designing highly scalable, available, and reliable cloud-native applications Practice Test 3 — 15 Questions

Question 1

A company is designing a global e-commerce application that needs low-latency access for users worldwide. The application serves static content (images, CSS) and dynamic API responses. Which Google Cloud service should they use to cache both types of content at the edge?

Accepted Answer

Cloud CDN. Cloud CDN is the correct choice because it uses Google's global edge cache to deliver both static content (e.g., images, CSS) and dynamic API responses (via cacheable dynamic content or cache-fill from origin). It integrates with HTTP(S) Load Balancing to cache responses at edge locations, reducing latency for users worldwide.

Answer

Cloud Armor

Answer

Cloud Storage

Answer

HTTP(S) Load Balancing

Question 2

A team is deploying a microservices application on Google Kubernetes Engine (GKE). They want to ensure that if a pod fails, Kubernetes automatically replaces it and maintains the desired number of replicas. Which Kubernetes resource should they use?

Accepted Answer

Deployment. A Deployment is the correct Kubernetes resource for managing stateless microservices that require automatic pod replacement to maintain a desired replica count. It uses a ReplicaSet to ensure the specified number of pod replicas are running, and if a pod fails, the ReplicaSet controller immediately creates a new pod to restore the desired state.

Answer

StatefulSet

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Job

Answer

DaemonSet

Question 3

An online gaming platform uses Cloud Spanner as its globally distributed database. They notice that write latency increases significantly during peak hours. The application performs many single-row writes with high consistency requirements. Which design change would most effectively reduce write latency?

Accepted Answer

Use interleaved tables to colocate related rows.. Interleaved tables in Cloud Spanner physically colocate parent and child rows, reducing the number of splits and cross-node round trips for related single-row writes. This minimizes distributed transaction overhead and write latency, especially under high consistency requirements, without requiring additional nodes or sacrificing consistency.

Answer

Increase the number of nodes in the Spanner instance.

Answer

Switch to eventual consistency mode for writes.

Answer

Split the table into multiple smaller tables.

Question 4

A company runs a batch job that processes large files from Cloud Storage every night. The job must complete within a 2-hour window. If the job fails, it should retry automatically. Which Google Cloud service should they use to orchestrate this job?

Accepted Answer

Cloud Composer. Cloud Composer (D) is the correct choice because it is a fully managed workflow orchestration service built on Apache Airflow, designed to schedule, monitor, and retry batch jobs with complex dependencies. It can trigger a Cloud Storage file processing job, enforce a 2-hour execution window, and automatically retry on failure using Airflow's built-in retry mechanisms and SLA monitoring.

Answer

Compute Engine with startup script

Answer

Cloud Run

Answer

App Engine Cron

Question 5

A development team is using Cloud Build to deploy containerized applications to GKE. They want to ensure that only containers that have passed security scans and unit tests are deployed to production. Which approach should they use?

Accepted Answer

Use Cloud Build with a multi-step pipeline that includes test and security scan steps, and only promote to production after successful completion.. Using a multi-step Cloud Build pipeline with test and security scan steps, and then promoting to production only after success, ensures only validated containers are deployed. Direct deployment to production on every push is risky. Manual promotion defeats automation. Cloud Deploy adds unnecessary complexity for this simple requirement. Thus, option B is correct.

Answer

Deploy to a staging cluster first, then manually promote to production using kubectl.

Answer

Use Cloud Deploy to automate delivery with approval gates.

Answer

Configure Cloud Build triggers to deploy directly to production on every push.

Question 6

A financial services company uses Cloud Spanner for transactional data. They need to perform complex analytical queries that aggregate large volumes of data without affecting the performance of transaction processing. Which approach should they take?

Accepted Answer

Export data from Spanner to BigQuery periodically and run analytic queries there.. Option C is correct because BigQuery is a serverless, highly scalable data warehouse designed for complex analytical queries on large datasets. By exporting Spanner transactional data to BigQuery, the company can run heavy aggregations without impacting Spanner's OLTP performance, as Spanner is optimized for high-throughput, low-latency transactions, not analytical workloads.

Answer

Use Spanner's read-only transactions to run analytic queries.

Answer

Enable Cloud Spanner's query optimizer for analytical workloads.

Answer

Create secondary indexes on the Spanner tables to speed up analytical queries.

Question 7

A startup is building a REST API on Cloud Run. They expect unpredictable traffic spikes and want to ensure the service can scale from 0 to many instances automatically. What scaling configuration should they use?

Accepted Answer

Set min instances to 0 and max instances to 1000.. Option B is correct because Cloud Run's autoscaling allows min instances to be set to 0, enabling the service to scale down to zero when idle (cost-efficient), and max instances to 1000 to handle unpredictable traffic spikes by scaling out horizontally. This configuration ensures the service can start from zero and automatically add instances up to the maximum limit as demand increases, which is ideal for unpredictable workloads.

Answer

Set max instances to 1 to control costs.

Answer

Use manual scaling with a fixed number of instances.

Answer

Set min instances to 5 and max to 100.

Question 8

A media streaming company uses Cloud Storage to store video files. Users upload files through a web application, and the files are streamed directly from Cloud Storage. They want to reduce latency for users in different regions. Which configuration should they apply?

Accepted Answer

Set up Cloud CDN with the Cloud Storage bucket as origin.. Cloud CDN caches video content at edge locations worldwide, reducing latency for users by serving content from the nearest edge cache instead of the origin Cloud Storage bucket. This directly addresses the requirement to reduce latency for users in different regions without modifying the storage architecture.

Answer

Enable Object Lifecycle Management to move objects to Nearline storage.

Answer

Configure Cloud Storage transfer service to replicate data to multiple buckets.

Answer

Use a multi-region Cloud Storage bucket and enable requester-pays.

Question 9

A company runs a critical application on Compute Engine with a stateful database. They need to achieve 99.99% availability for the database tier. Which architecture should they implement?

Accepted Answer

A Compute Engine instance group with managed instance groups and a regional persistent disk configured for synchronous replication.. Option A is correct because a managed instance group with a regional persistent disk configured for synchronous replication provides the necessary 99.99% availability by ensuring the database runs across two zones with synchronous writes to both replicas. This architecture allows automatic failover within seconds if one zone fails, meeting the high-availability requirement without data loss.

Answer

Use Cloud SQL with automatic failover and read replicas.

Answer

Two Compute Engine instances in different zones with a shared Zonal persistent disk.

Answer

Single Compute Engine instance with a persistent disk snapshot scheduled every hour.

Question 10

A company is designing a scalable web application on Google Cloud. They expect variable traffic and want to automatically scale resources based on load. Which two services can automatically scale? (Choose two.)

Accepted Answer

Cloud Run. Cloud Run is a fully managed serverless compute platform that automatically scales your containerized applications based on incoming traffic, including scaling to zero when there is no traffic. This autoscaling is handled by the Knative serving layer, which adjusts the number of container instances based on request concurrency and CPU utilization.

Answer

Compute Engine unmanaged instance group

Answer

Cloud Dataproc

Answer

Cloud SQL

Question 11

A team is designing a cloud-native application that must be highly available and resilient to zone failures. Which three practices should they follow? (Choose three.)

Accepted Answer

Deploy resources across multiple zones.. Option B is correct because deploying resources across multiple zones ensures that the application remains available even if an entire zone fails. In Google Cloud, zones are independent failure domains, and distributing workloads across them is a fundamental pattern for achieving high availability and resilience to zone-level outages.

Answer

Use a single Load Balancer with multiple backends.

Answer

Use zonal managed instance groups with 100% target utilization.

Question 12

A company uses Cloud Spanner for a globally distributed application. They need to design their table schema for maximum scalability and performance. Which two design considerations are critical? (Choose two.)

Accepted Answer

Use interleaved tables to colocate related data.. Interleaved tables in Cloud Spanner physically colocate parent and child rows on the same split, reducing cross-node reads and improving join performance. This design is critical for globally distributed applications because it minimizes latency and ensures that related data is stored together for efficient access.

Answer

Store large binary blobs directly in Spanner.

Answer

Define secondary indexes on every column.

Answer

Use monotonically increasing primary keys.

Question 13

A team created the instance template above and used it in a managed instance group. However, instances fail to serve web traffic. What is the most likely cause?

Accepted Answer

The startup script does not configure a firewall rule to allow HTTP traffic.. The instance template likely includes a startup script that installs and starts Nginx, but does not configure a firewall rule (e.g., via `gcloud compute firewall-rules create` or `iptables`) to allow inbound HTTP traffic on port 80. By default, GCP VPC firewall rules deny all ingress traffic unless explicitly allowed, so even if Nginx is running, external requests will be blocked. This is the most common reason why a managed instance group fails to serve web traffic despite the application being installed.

Answer

The image family debian-11 does not have the necessary packages.

Answer

The machine type e2-medium is too small for Nginx.

Answer

The instance template is missing a service account.

Question 14

A security engineer applied the IAM policy above to a Cloud Storage bucket. The service account "my-sa" is used by an application that needs to read and write files to the bucket. The application reports that it cannot write files. What is the issue?

Accepted Answer

The "roles/storage.objectCreator" role only allows creating new objects, but not overwriting existing ones.. The 'roles/storage.objectCreator' role grants permission to create new objects in a Cloud Storage bucket, but it does not allow overwriting existing objects. To overwrite objects, the 'roles/storage.objectAdmin' or 'roles/storage.legacyObjectOwner' role is required, which includes the storage.objects.update permission. Since the application needs to both read and write (including overwrite) files, the objectCreator role is insufficient.

Answer

The policy is missing the "roles/storage.objectAdmin" role.

Answer

The service account lacks permission to list bucket contents.

Answer

The policy has duplicate bindings that cause a conflict.

Question 15

A developer deployed the above Cloud Run service YAML. The service deploys successfully but any request fails with a 503 error. What is the most likely cause?

Accepted Answer

The container is not listening on the expected port.. A 503 error from Cloud Run indicates that the service is failing to respond to health checks or requests. The most common cause is that the container is not listening on the port specified in the `containerPort` field of the YAML (default 8080). Cloud Run sends requests to that port, and if the application is bound to a different port (e.g., 3000 or 80), the request never reaches the application, resulting in a 503.

Answer

The service has no ingress setting.

Answer

The container image has a different entrypoint.

Answer

containerConcurrency is set too high.