PCD Designing highly scalable, available, and reliable cloud-native applications Practice Test 2 — 15 Questions

Question 1

An administrator runs the above command to create a Compute Engine instance. However, the nginx service does not start. What is the most likely cause?

Accepted Answer

The instance has no external IP address and cannot reach the internet to download packages.. The command likely creates a Compute Engine instance without specifying an external IP address (e.g., using `--no-address` or omitting `--address`). Without an external IP, the instance cannot reach the internet to download the nginx package from repositories, causing the startup script that installs and starts nginx to fail. This is the most direct cause of the nginx service not starting.

Answer

The metadata key is misspelled; it should be 'startup-script-url'.

Answer

The instance does not have the compute.instance.update permission.

Answer

The startup script runs before the boot disk is fully mounted.

Question 2

A company is designing a highly available application on Google Cloud using multiple regions. Which TWO strategies should they implement to achieve this?

Accepted Answer

Use a global load balancer to distribute traffic across regions.. A global load balancer (e.g., Google Cloud External HTTPS Load Balancer) can distribute traffic across multiple regions, providing cross-region failover and low-latency routing. This is a fundamental pattern for multi-region high availability, as it allows traffic to be directed to healthy backends in any region, even if an entire region fails.

Answer

Use zonal persistent disks for stateful data.

Answer

Deploy a single instance group in one region for simplicity.

Answer

Store all data in a single Cloud Storage bucket.

Question 3

A team is deploying a critical application on Google Kubernetes Engine (GKE) and needs to ensure high availability and disaster recovery. Which THREE actions should they take?

Accepted Answer

Use a regional cluster with control plane replicated across zones.. A regional cluster in GKE replicates the control plane across multiple zones within a region, ensuring that if one zone fails, the control plane remains available. This is essential for high availability and disaster recovery, as it eliminates a single point of failure for cluster management operations.

Answer

Deploy all pods in a single zone for simplicity.

Answer

Use a zonal cluster to reduce costs.

Question 4

A company is deploying a microservices-based application on Google Kubernetes Engine (GKE). The application consists of several stateless services that experience unpredictable traffic spikes. The team wants to ensure high availability and scalability while minimizing costs. Which design should they implement?

Accepted Answer

Deploy a Regional GKE cluster with cluster autoscaling and Horizontal Pod Autoscaler for each deployment.. A Regional GKE cluster provides multi-zone high availability, cluster autoscaling dynamically adjusts node pool size to handle unpredictable traffic spikes, and Horizontal Pod Autoscaler (HPA) scales individual pod replicas based on CPU/memory or custom metrics. This combination ensures both scalability and cost efficiency by only provisioning resources when needed.

Answer

Deploy a Regional GKE cluster with node auto-provisioning and a fixed number of replicas per service.

Answer

Use a Regional GKE cluster with preemptible VMs and static pod counts.

Answer

Use a single-zone GKE cluster with a large fixed node pool to handle peak load.

Question 5

You are troubleshooting a web application deployed on Compute Engine instances behind a target pool. Users report intermittent timeouts when accessing the application via the forwarding rule's IP address. Based on the exhibit, what is the most likely cause of the issue?

Accepted Answer

The target pool lacks health checks, causing traffic to be sent to unhealthy instances.. The target pool in a legacy HTTP(S) load balancer does not automatically perform health checks unless they are explicitly configured. Without health checks, the load balancer continues to send traffic to all instances in the pool, including those that are unhealthy or unresponsive. This causes intermittent timeouts when users hit an unhealthy instance, as the forwarding rule distributes connections across the entire pool without verifying instance health.

Answer

The forwarding rule is missing a backend service.

Answer

The port range is set to 80-80, which restricts traffic to port 80 only.

Answer

The forwarding rule should use a backend service instead of a target pool for HTTP traffic.

Question 6

A company is designing a globally distributed application using Cloud Spanner. The application requires strong consistency and the ability to handle high read/write throughput. The team is concerned about inter-continental latency. Which two design choices would optimize performance while maintaining strong consistency? (Choose two.)

Accepted Answer

Enable leader-optimized routing to direct reads to the nearest leader region.. A is correct because leader-optimized routing directs read requests to the nearest region that contains the leader replica for the requested data, reducing inter-continental latency while still reading from the leader to ensure strong consistency. C is correct because placing a multi-region Spanner instance in geographic locations close to users minimizes network round-trip time, and Spanner's synchronous replication across regions maintains strong consistency even with high read/write throughput.

Answer

Use read-only replicas in each continent to serve reads locally.

Answer

Implement client-side caching with a short TTL for frequently accessed data.

Answer

Increase the number of nodes in the Spanner instance to improve throughput.

Question 7

A team is building a serverless event-driven application using Cloud Functions and Cloud Pub/Sub. The function processes messages from a Pub/Sub subscription and writes results to Firestore. During peak hours, the function experiences high latency and some messages are being retried multiple times. Which three steps should the team take to improve reliability and scalability? (Choose three.)

Accepted Answer

Enable retry policy on the Pub/Sub subscription to automatically retry failed messages.. Enabling a retry policy on the Pub/Sub subscription ensures that messages that fail to be processed (e.g., due to transient errors or timeouts) are automatically retried. This prevents message loss and improves reliability by allowing the Cloud Function to reprocess messages without manual intervention. The retry policy works with the subscription's acknowledgement deadline, so messages are redelivered if not acknowledged in time.

Answer

Batch multiple Pub/Sub messages into a single Cloud Function invocation.

Answer

Increase the Cloud Function timeout to the maximum allowed value.

Question 8

A company runs a stateful application on Compute Engine instances with persistent disks. The application must be highly available and be able to recover from a zonal failure with minimal data loss. The current architecture uses a single instance in one zone. Which design should the team implement?

Accepted Answer

Use a regional persistent disk attached to a managed instance group across two zones.. A regional persistent disk synchronously replicates data across two zones, and when attached to a managed instance group (MIG) spanning those zones, it provides automatic failover with minimal data loss. This design ensures that if one zone fails, the MIG can detach the disk from the failed instance and attach it to a healthy instance in the surviving zone, preserving state with near-zero RPO.

Answer

Use a standard persistent disk and configure a global load balancer to failover.

Answer

Create a snapshot schedule and restore the snapshot to a new instance in another zone on failure.

Answer

Migrate to Cloud Filestore for shared file storage across zones.

Question 9

A company is deploying a microservices application on Google Kubernetes Engine (GKE) and needs to ensure that services can discover each other without hardcoding IP addresses. Which approach should they use?

Accepted Answer

Use Cloud DNS with Kubernetes Services of type ClusterIP. Kubernetes Services of type ClusterIP provide a stable virtual IP and DNS name (via Cloud DNS) that resolves to the service's ClusterIP, enabling pods to discover each other without hardcoding IP addresses. GKE integrates with Cloud DNS to automatically register service DNS names in the format ..svc.cluster.local, allowing microservices to communicate reliably even if pods are rescheduled or IPs change.

Answer

Use environment variables injected into each pod

Answer

Use a ConfigMap to store service endpoints

Answer

Use Cloud Load Balancing to route traffic between services

Question 10

A company runs a stateful application on Compute Engine with regional persistent disks. They want to achieve high availability with automatic failover in case of a zone failure. Which architecture meets these requirements?

Accepted Answer

Use regional persistent disks with a managed instance group spanning two zones. Regional persistent disks synchronously replicate data across two zones, and when combined with a managed instance group (MIG) spanning those same two zones, the application can automatically fail over to the healthy zone if one zone fails. The MIG's autohealing and health-check mechanisms detect the failure and recreate instances in the surviving zone, while the regional PD remains accessible from either zone, ensuring high availability without manual intervention.

Answer

Use Cloud Storage FUSE to mount a multi-regional bucket as a filesystem

Answer

Use standard persistent disks with scheduled snapshots to a multi-region bucket

Answer

Use zonal persistent disks with a managed instance group in a single zone

Question 11

A developer is designing a serverless event-driven application that processes messages from Pub/Sub and writes results to BigQuery. The workload is unpredictable but must scale to zero when idle. Which compute option should they choose?

Accepted Answer

Cloud Functions with Pub/Sub trigger. Cloud Functions with a Pub/Sub trigger is the correct choice because it is purpose-built for event-driven, serverless workloads that scale to zero when idle. It automatically scales from zero to thousands of concurrent invocations based on the volume of Pub/Sub messages, and it natively integrates with Pub/Sub via a background function that is invoked for each message, making it ideal for unpredictable, bursty workloads that must process messages and write results to BigQuery.

Answer

Cloud Run with Pub/Sub push subscription

Answer

Compute Engine with managed instance groups

Answer

Google Kubernetes Engine with Horizontal Pod Autoscaler

Question 12

A company is migrating a monolithic application to a microservices architecture on Google Cloud. They want to decouple services and ensure that a failure in one service does not impact others. Which pattern should they implement?

Accepted Answer

Implement circuit breaker pattern using a service mesh like Istio. The circuit breaker pattern, implemented via a service mesh like Istio, is the correct approach because it prevents cascading failures by monitoring service health and stopping requests to a failing service until it recovers. Istio's Envoy sidecar proxies enforce circuit breaking at the network layer, allowing the system to degrade gracefully without impacting other services.

Answer

Implement caching with Memorystore

Answer

Increase the number of instances of each service

Answer

Use synchronous HTTP calls with retries

Question 13

Drag and drop the steps to create a Cloud Run service in the correct order.

Accepted Answer

Select container image, then configure service settings, then deploy the service. Creating a Cloud Run service involves selecting the container image and configuring settings before deployment.

Answer

Configure service settings, then select container image, then deploy the service

Answer

Deploy the service, then select container image, then configure service settings

Answer

Select container image, then deploy the service, then configure service settings

Question 14

Drag and drop the steps to set up a Cloud Function triggered by a Cloud Storage event in the correct order.

Accepted Answer

Write the Cloud Function code, then Deploy the function with the Cloud Storage bucket as trigger, then Upload a file to the Cloud Storage bucket, then Check the Cloud Function logs to verify execution. Cloud Functions can be triggered by Cloud Storage events; deployment includes specifying the bucket trigger.

Answer

Deploy the function with the Cloud Storage bucket as trigger, then Write the Cloud Function code, then Upload a file to the Cloud Storage bucket, then Check the Cloud Function logs to verify execution

Answer

Upload a file to the Cloud Storage bucket, then Write the Cloud Function code, then Deploy the function with the Cloud Storage bucket as trigger, then Check the Cloud Function logs to verify execution

Answer

Check the Cloud Function logs to verify execution, then Write the Cloud Function code, then Deploy the function with the Cloud Storage bucket as trigger, then Upload a file to the Cloud Storage bucket

Question 15

Match each Google Cloud service to its primary purpose.

Accepted Answer

Cloud Run: A fully managed compute platform for containerized applications.. Cloud Run deploys containers, Cloud Functions runs event-driven functions, and Cloud Storage stores unstructured objects. Common confusions include swapping the definitions of Cloud Run and Cloud Functions, or mistaking Cloud Storage for a database service like Cloud SQL.

Answer

Cloud Run: A serverless execution environment for building and connecting cloud services.

Answer

Cloud Storage: A fully managed relational database for MySQL, PostgreSQL, and SQL Server.