PCD Designing highly scalable, available, and reliable cloud-native applications Practice Test 6 — 15 Questions

Question 1

A company is migrating a stateful application to Google Cloud. They need high availability with automatic failover across zones within a region. Which compute option should they choose?

Accepted Answer

Google Kubernetes Engine with Regional Persistent Disk. Google Kubernetes Engine (GKE) with Regional Persistent Disk is the correct choice because it provides synchronous replication of data across multiple zones within a region, enabling automatic failover for stateful applications. When a pod or node fails in one zone, the Regional Persistent Disk can be immediately attached to a pod in another zone, ensuring high availability without data loss. This meets the requirement for stateful workloads that need zone-level resilience.

Answer

App Engine Standard Environment

Answer

Cloud Run

Answer

Compute Engine with standard persistent disk

Question 2

A team deploys a containerized application on Cloud Run and notices increased latency during traffic spikes due to cold starts. Which configuration change would best address this?

Accepted Answer

Set min_instances to a value greater than 0. Option A is correct because setting min_instances to a value greater than 0 keeps a baseline of warm instances ready to handle traffic, reducing cold starts. Option B is wrong because increasing max_instances does not prevent cold starts. Option C is wrong because enabling CPU always allocated does not create new instances. Option D is wrong because setting concurrency to 1 limits throughput, worsening scaling behavior.

Answer

Set concurrency to 1

Answer

Enable CPU always allocated

Answer

Increase max_instances

Question 3

A financial trading application on Compute Engine requires an RPO of 5 seconds and RTO of 1 minute for zone failures. Which architecture should they use?

Accepted Answer

Regional persistent disk attached to a single instance. Regional persistent disks provide synchronous replication of data between two zones within a region, ensuring an RPO of effectively zero (typically under 5 seconds) and enabling rapid failover to a secondary zone. By attaching the regional disk to a single Compute Engine instance, the application can quickly resume operations in the other zone upon failure, meeting the 1-minute RTO without data loss or complex replication overhead.

Answer

Persistent disk with periodic snapshots to a different zone

Answer

Managed instance group with autoscaling and health checks

Answer

Two instances in different zones with data replicated via rsync

Question 4

A web application uses Cloud SQL for MySQL. The team expects a sudden spike in read-only traffic from a reporting tool. What should they use to offload read queries?

Accepted Answer

Read replicas. Read replicas in Cloud SQL for MySQL allow you to offload read traffic from the primary instance by creating one or more read-only copies. This is the correct approach for handling a sudden spike in read-only queries from a reporting tool, as it distributes the load without affecting write performance or requiring application changes beyond updating the connection string.

Answer

Automatic storage increase

Answer

Cross-region replication

Answer

Failover replica

Question 5

A stateful service on GKE needs to persist data that must be accessible from any pod in the cluster, regardless of which node the pod runs on. Which volume type should they use?

Accepted Answer

PersistentVolumeClaim with RWX access mode. A PersistentVolumeClaim (PVC) with RWX (ReadWriteMany) access mode is correct because it allows multiple pods across different nodes to read and write to the same persistent volume simultaneously. This is essential for a stateful service where data must be accessible from any pod in the cluster, regardless of which node the pod runs on. RWX is typically backed by network filesystems like NFS or GKE Filestore, which provide shared access across nodes.

Answer

emptyDir

Answer

ConfigMap

Answer

hostPath

Question 6

An application on Cloud Run needs to connect to a Cloud SQL instance securely with minimal latency. It also needs to access Cloud Storage buckets in the same region. Which networking configuration should they use?

Accepted Answer

Serverless VPC Access connector with Private Services Access for Cloud SQL. Option A is correct because Serverless VPC Access allows Cloud Run to reach VPC resources, and Private Services Access enables Cloud SQL to have an internal IP within the VPC, minimizing latency. Option B is wrong because Cloud NAT is for outbound internet, not internal connectivity. Option C is wrong because direct VPC peering is not directly applicable to Cloud Run. Option D is wrong because the Cloud SQL Auth Proxy with public IP introduces additional latency and security concerns.

Answer

Cloud NAT for outbound traffic

Answer

Direct VPC peering with Cloud SQL

Answer

Use Cloud SQL Auth Proxy with public IP

Question 7

A media company wants to serve video content globally with low latency and high throughput. Which Google Cloud service is best suited?

Accepted Answer

Cloud CDN. Cloud CDN leverages Google's global edge cache network to deliver video content from locations closest to end users, minimizing latency and offloading origin servers. It integrates with Cloud Load Balancer and Cloud Storage to provide high-throughput, low-latency streaming without requiring users to manage caching infrastructure.

Answer

Cloud Load Balancer

Answer

Cloud Storage with public bucket

Answer

App Engine

Question 8

A team runs a microservice on Compute Engine behind a regional external HTTP load balancer. They want to automatically replace unhealthy instances without manual intervention. Which feature should they use?

Accepted Answer

Managed instance group with autoscaling and health check. A managed instance group (MIG) with autoscaling and a health check is the correct choice because it automatically replaces unhealthy instances based on the health check results. The MIG uses the health check to detect failed instances, then automatically recreates them from the instance template, ensuring high availability without manual intervention. Autoscaling further adjusts the number of instances based on load, but the core replacement mechanism is driven by the MIG's health check and autohealing feature.

Answer

Unmanaged instance group with health check

Answer

Instance template with manual replacement

Answer

Load balancer backend service health check only

Question 9

A multi-region application uses Cloud Spanner. The team needs to ensure that a write is immediately visible to all subsequent reads, even those performed in different regions. Which consistency mode should they use?

Accepted Answer

Strong consistency. Strong consistency (D) ensures that once a write is acknowledged, any subsequent read, regardless of region, will reflect that write. Cloud Spanner uses the TrueTime API and Paxos-based replication to provide external consistency (a form of strong consistency) across regions, making it the correct choice for immediate global visibility.

Answer

Eventual consistency

Answer

Global consistency

Answer

Bounded staleness

Question 10

A company deploys a microservice on Cloud Run and wants to minimize cold starts during traffic spikes. Which two steps should they take? (Select exactly 2.)

Accepted Answer

Enable CPU always allocated. Enabling CPU always allocated (option A) prevents the CPU from being throttled when the container is not handling requests, which reduces cold start latency because the runtime environment remains warm and ready to process incoming traffic immediately. This is particularly effective for minimizing cold starts during traffic spikes because the container's CPU is always active, eliminating the need to spin up resources from a cold state.

Answer

Use Cloud CDN

Answer

Set max_instances to a high value

Answer

Set concurrency to 1

Question 11

A team uses Google Kubernetes Engine (GKE) with Node Auto-Provisioning. They want to optimize cost while maintaining high availability across zones. Which two strategies should they implement? (Select exactly 2.)

Accepted Answer

Use cluster autoscaler with appropriate min and max node counts. Option A is correct because Node Auto-Provisioning (NAP) in GKE works in conjunction with the cluster autoscaler to automatically create and delete node pools based on workload demands. By setting appropriate minimum and maximum node counts, you ensure the cluster can scale down to zero when idle (saving cost) and scale up to handle peak load, while avoiding runaway scaling that could increase costs unexpectedly.

Answer

Use preemptible VMs for all node pools

Answer

Disable cluster autoscaler to prevent scaling

Answer

Use sole-tenant nodes for high availability

Question 12

A company runs a stateful application on Compute Engine. They need to achieve an RPO of less than 15 minutes and an RTO of less than 30 minutes for a regional disaster. Which three steps should they include in their disaster recovery plan? (Select exactly 3.)

Accepted Answer

Develop custom scripts to replicate application data asynchronously to another region. Option B is correct because asynchronous replication of application data to another region can achieve an RPO of less than 15 minutes and an RTO of less than 30 minutes, as it allows the application to fail over to a secondary region with minimal data loss. Custom scripts can control replication frequency and ensure data consistency, meeting the strict RPO requirement.

Answer

Use a managed instance group in multiple zones within the same region

Answer

Use regional persistent disks to replicate data within the region

Question 13

A startup is deploying a stateless web app on Compute Engine. They expect traffic spikes. What is the most cost-effective way to handle scaling?

Accepted Answer

Use managed instance groups with autoscaling based on CPU utilization.. Managed instance groups (MIGs) with autoscaling based on CPU utilization are the most cost-effective solution for a stateless web app with traffic spikes because they automatically add or remove VM instances in response to real-time CPU load, ensuring you only pay for the compute resources you actually use. This approach directly matches the stateless nature of the app, allowing instances to be created and destroyed without data loss, and avoids over-provisioning or under-utilizing resources.

Answer

Use App Engine Standard.

Answer

Use a single large VM with more cores.

Answer

Use Cloud Functions.

Question 14

A company wants to run a batch job every hour that processes files from Cloud Storage. The job takes about 10 minutes. Which serverless option should they use?

Accepted Answer

Cloud Functions with Cloud Scheduler. Cloud Functions triggered by Cloud Scheduler is ideal for periodic, short-lived batch jobs that process files. Cloud Run Jobs is also suitable but less event-driven. Compute Engine requires manual setup. App Engine Cron Service is possible but more complex.

Answer

Cloud Run jobs

Answer

Compute Engine with cron

Answer

App Engine Cron Service with Cloud Tasks

Question 15

A developer needs to store session state for a user in a cloud-native application. Which storage solution is most appropriate?

Accepted Answer

Memorystore. Memorystore (Redis) is the most appropriate solution for storing session state in a cloud-native application because it provides an in-memory data store with sub-millisecond latency, which is critical for fast session reads and writes. Session state is ephemeral, key-value data that requires high throughput and low latency, and Memorystore supports features like TTL (time-to-live) for automatic session expiration and persistence options for durability. This aligns with the cloud-native principle of stateless application tiers offloading state to a managed caching layer.

Answer

Cloud SQL

Answer

Cloud Storage

Answer

Bigtable