PCD Designing highly scalable, available, and reliable cloud-native applications Practice Test 8 — 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?

Choose an answer to begin — your selection is scored in the full session.

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

Answer

Job

Answer

DaemonSet

Question 3

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 4

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.. 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 5

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 6

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 (B) is correct because it is a fully managed serverless platform that automatically scales containerized workloads up and down based on incoming request traffic, including scaling to zero when idle. Compute Engine managed instance groups (C) are correct because they support autoscaling policies (such as CPU utilization, load balancing serving capacity, or custom metrics) that automatically add or remove VM instances based on load. Compute Engine unmanaged instance groups (A) do not provide autoscaling, since they are just collections of dissimilar instances without a common instance template. Cloud Dataproc (D) is a managed Hadoop/Spark service for batch and data processing, not a web application autoscaling service. Cloud SQL (E) is a managed relational database that can scale storage or vertically resize, but it does not automatically scale application resources based on web traffic load.

Answer

Compute Engine unmanaged instance group

Answer

Cloud Dataproc

Answer

Cloud SQL

Question 7

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 spreading resources across multiple zones ensures that a failure of any single zone does not take down the entire application, which is the foundation of zone-failure resilience. Option D is correct because regional persistent disks synchronously replicate data across two zones in the same region, so a zone outage does not cause data loss or unavailability. Option E is correct because health checks detect unhealthy instances and autohealing automatically recreates them, maintaining capacity and availability without manual intervention. Option A is not sufficient on its own: a single load balancer with multiple backends can still have all backends in one zone, so it does not inherently provide zone-failure resilience. Option C is incorrect because zonal managed instance groups are confined to a single zone, and running at 100% target utilization leaves no headroom to absorb failures or traffic spikes.

Answer

Use a single Load Balancer with multiple backends.

Answer

Use zonal managed instance groups with 100% target utilization.

Question 8

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.. Option A is correct because interleaved tables physically colocate child rows with their parent row, so related data is stored on the same node and joins between parent and child can be executed locally without network shuffling, which improves performance and scalability for hierarchical data. Option E is correct because Cloud Spanner shards data by primary key ranges, so choosing keys that spread writes evenly across nodes (for example, using hashed or reversed keys) avoids hotspots and lets the system scale horizontally. Option B is not appropriate because Spanner is optimized for structured relational data and large binary blobs should be stored in Cloud Storage with references in Spanner. Option C is wrong because indexing every column adds write amplification and storage overhead without query benefit. Option D is wrong because monotonically increasing primary keys (such as timestamps or sequential IDs) concentrate writes on the last key range, creating a hotspot that limits scalability.

Answer

Store large binary blobs directly in Spanner.

Answer

Define secondary indexes on every column.

Answer

Use monotonically increasing primary keys.

Question 9

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.

Question 10

An e-commerce company relies on a Compute Engine backend serving content to global users. They notice high latency for users outside the primary region. Which service should they add to reduce latency by caching content at edge locations?

Accepted Answer

Cloud CDN. Cloud CDN (Content Delivery Network) uses Google's global edge cache locations to serve cached content closer to users, reducing latency for requests that would otherwise travel to the origin Compute Engine backend in a single region. By caching static or dynamic content at edge nodes, Cloud CDN minimizes round-trip time and offloads traffic from the backend instance.

Answer

Cloud Armor

Answer

Cloud NAT

Answer

Cloud Endpoints

Answer

Cloud Load Balancing

Question 11

A startup expects low and predictable traffic initially but wants to use containers with minimal operational overhead. Which compute service should they choose?

Accepted Answer

Cloud Run. Cloud Run is the correct choice because it runs containers in a fully managed, serverless environment that automatically scales from zero, requires no cluster management, and charges only for resources used during request processing. This matches the startup's need for minimal operational overhead and low, predictable traffic, as Cloud Run abstracts away infrastructure management entirely.

Answer

App Engine Flexible Environment

Answer

Google Kubernetes Engine (GKE)

Answer

Compute Engine

Answer

Cloud Functions

Question 12

A company runs a stateful microservice that requires read-after-write consistency but can tolerate some latency for writes. They are currently using a single Cloud SQL instance and want to scale read traffic. Which approach should they take?

Accepted Answer

Enable Cloud SQL read replicas. Cloud SQL read replicas are the correct choice because they provide an asynchronous read-only copy of the primary instance, which can scale read traffic without compromising the read-after-write consistency required by the stateful microservice. The primary instance handles all writes, ensuring strong consistency for writes, while replicas serve stale reads that eventually become consistent, which aligns with the tolerance for write latency.

Answer

Use Cloud Memorystore to cache reads

Answer

Shard the database manually

Answer

Use Cloud Bigtable

Answer

Migrate to Cloud Spanner

Question 13

A company uses Cloud Functions to process events from Pub/Sub. They notice that occasionally the same message is processed more than once. What can they do to ensure idempotent processing?

Accepted Answer

Make the function idempotent using a deduplication field. Making the function idempotent using a deduplication field ensures that even if the same Pub/Sub message is delivered more than once (Pub/Sub offers at-least-once delivery), the function processes it only once. By checking a unique message ID or a custom deduplication key before processing, the function can skip or safely reapply the operation, preventing duplicate side effects.

Answer

Configure retry policies to only retry once

Answer

Use Cloud Tasks instead

Answer

Use Cloud Scheduler

Answer

Increase the acknowledgement deadline for the subscription

Question 14

A company uses Cloud SQL for MySQL and wants to achieve high availability with automatic failover across zones while minimizing data loss. Which configuration should they use?

Accepted Answer

Configure a regional Cloud SQL instance with automatic failover. A regional Cloud SQL instance with automatic failover provides synchronous replication of data between two zones within the same region, ensuring zero data loss (RPO=0) and automatic failover with minimal downtime (RTO typically under 60 seconds). This meets the requirement for high availability with automatic failover across zones while minimizing data loss.

Answer

Enable read replicas in different zones

Answer

Use external read replicas with a failover script

Answer

Use Cloud SQL Enterprise Plus edition

Answer

Enable point-in-time recovery

Question 15

A company uses Cloud Load Balancing to distribute traffic to HTTP backends. They want to protect against application-layer DDoS attacks (e.g., HTTP flood). Which TWO services should they combine?

Accepted Answer

Cloud Armor. Cloud Armor (D) is correct because it provides Google Cloud's edge security service with WAF rules and rate-based ban rules that specifically mitigate application-layer (L7) DDoS attacks such as HTTP floods by filtering or throttling malicious requests before they reach the backends. Cloud CDN (E) is correct because caching content at Google's edge absorbs and offloads large volumes of repeated HTTP requests, reducing the load that reaches the origin and thereby blunting HTTP flood impact when combined with Cloud Armor's filtering. Cloud Firewall rules (A) operate at L3/L4 for VPC traffic and cannot inspect HTTP semantics to stop application-layer floods. Cloud NAT (B) only provides outbound address translation for private instances and offers no inbound attack protection. Cloud Endpoints (C) is an API management and authentication layer, not a DDoS mitigation or caching service.

Answer

Cloud Firewall rules

Answer

Cloud NAT

Answer

Cloud Endpoints