PCD Practice Test 32 — 15 Questions

Question 1

A company runs a batch job daily that processes large files from Cloud Storage and stores results in BigQuery. The job requires significant compute for about 10 minutes and is fault-tolerant. Which compute option is most cost-effective?

Accepted Answer

Preemptible VM. Option D is correct because Preemptible VMs offer the same compute capacity as regular VMs at a significantly lower cost (up to 80% discount), and since the batch job runs for only 10 minutes daily and is fault-tolerant, it can handle the occasional preemption without data loss. The job's short duration and fault tolerance make preemptible instances ideal, as they can be restarted if terminated.

Answer

Cloud Run Jobs

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Always-on Compute Engine VM

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GKE cluster with a single node

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Cloud Functions (9-minute timeout)

Question 2

A company is designing a microservices application. They want to ensure that if one service fails, it does not cascade to other services. Which pattern should they implement?

Accepted Answer

Circuit Breaker. The Circuit Breaker pattern is the correct choice because it prevents cascading failures by monitoring service calls and opening the circuit when failures exceed a threshold, allowing the system to fail fast and avoid resource exhaustion. This pattern directly addresses the requirement to isolate failures between microservices, ensuring that a failure in one service does not propagate to others.

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Auto-scaling

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Retry with exponential backoff

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Load shedding

Question 3

A company uses Cloud Spanner for a global application. They want to improve read performance for point-reads (individual row lookups). Which TWO strategies should they adopt?

Accepted Answer

Create secondary indexes. Secondary indexes in Cloud Spanner allow point-reads to be served directly from the index table, avoiding a full table scan and reducing latency. Interleaved tables store child rows physically adjacent to their parent row, enabling efficient single-row lookups without cross-node coordination.

Answer

Use read replicas

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Partition the table by time

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Use batch reads

Question 4

Which two design patterns help decouple microservices?

Accepted Answer

Event-driven architecture. Event-driven architecture (B) decouples microservices by allowing them to communicate asynchronously through events, eliminating direct dependencies between services. This pattern uses a message broker (e.g., Kafka, RabbitMQ) to publish and consume events, enabling services to evolve independently without blocking each other.

Answer

Service mesh

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Database per service

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Circuit breaker

Question 5

Refer to the exhibit. The user developer@example.com tries to create a firewall rule and receives a permission denied error. What is the most likely reason?

Accepted Answer

The user lacks compute.networkAdmin role. The correct answer is D: All of the above. Creating a firewall rule in Google Cloud requires the `compute.securityAdmin` role (which includes `compute.firewalls.create` permission) or the `compute.networkAdmin` role (which also includes `compute.firewalls.create` permission). If the user lacks any of these roles or the specific permission, they will receive a permission denied error. Option A, B, and C are all individually correct reasons, making D the most comprehensive and accurate choice.

Question 6

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 is correct because it provides Web Application Firewall (WAF) capabilities and DDoS protection at the application layer, allowing you to create security policies that filter HTTP/HTTPS traffic based on IP addresses, geo-locations, or custom rules (e.g., rate limiting) to mitigate HTTP flood attacks. Cloud CDN is correct because it caches content at edge locations, absorbing a significant portion of malicious traffic before it reaches the backend, reducing the load on origin servers and acting as a first line of defense against volumetric application-layer attacks.

Answer

Cloud Firewall rules

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Cloud NAT

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Cloud Endpoints

Question 7

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

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Cloud Storage

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Bigtable

Question 8

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.

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Cloud Armor

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Cloud NAT

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Cloud Endpoints

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Cloud Load Balancing

Question 9

A team is migrating a monolithic app to microservices. They need to handle distributed transactions across services. Which pattern should they use?

Accepted Answer

Saga pattern. The Saga pattern is the correct choice for managing distributed transactions across microservices because it breaks a long-lived transaction into a sequence of local transactions, each with a compensating action to roll back if a subsequent step fails. This avoids the tight coupling and performance bottlenecks of distributed locking or two-phase commit, which are unsuitable for cloud-native, highly scalable environments. Sagas can be orchestrated (via a coordinator) or choreographed (via events), and they align with eventual consistency principles required for high availability.

Answer

Eventual consistency with compensation

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Distributed lock manager

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Two-phase commit

Question 10

A company is deploying a global microservices application on Cloud Run. They need to design for high availability, scalability, and low latency. Which three practices should they implement? (Choose three.)

Accepted Answer

Enable Cloud CDN for caching static assets.. Option B is correct because Cloud CDN caches static assets at Google's global edge locations, reducing latency for users worldwide and offloading requests from Cloud Run. This improves performance for static content like images, CSS, and JavaScript, which is essential for a global microservices application requiring low latency.

Answer

Use Cloud Scheduler to trigger services periodically.

Answer

Set a limit on the number of Cloud Run containers per revision to control costs.

Question 11

A company is designing a microservices architecture on Google Kubernetes Engine (GKE). They want to ensure zero-downtime deployments. Which strategy should they use?

Accepted Answer

Blue/green deployment. Blue/green deployment is the correct strategy for achieving zero-downtime deployments on GKE because it runs two identical environments (blue and green) and switches traffic instantly via a Kubernetes Service or Ingress. This eliminates any period where the application is unavailable, as the old version remains live until the new version is fully ready and traffic is cut over. GKE's LoadBalancer or Ingress controller can route all traffic to the new environment with a single configuration update, ensuring no requests are dropped.

Answer

Recreate

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Rolling update

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Canary deployment

Question 12

A financial services company has a critical application that must survive a regional outage. They deployed on Compute Engine across multiple zones within a single region and now want to redirect traffic to a secondary region if the primary region becomes unavailable. Which load balancing solution should they use?

Accepted Answer

External HTTP(S) Load Balancer. The External HTTP(S) Load Balancer is the correct choice because it supports global load balancing across multiple regions, enabling traffic failover to a secondary region when the primary region becomes unavailable. It uses anycast IP addresses and is designed for HTTP/S traffic, making it suitable for a critical application that must survive a regional outage.

Answer

SSL Proxy Load Balancer

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Proxy Network Load Balancer

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Internal TCP/UDP Load Balancer

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Network Load Balancer

Question 13

A developer is building an event-driven system using Cloud Pub/Sub. They need to ensure reliable message delivery and processing. Which three practices should they follow?

Accepted Answer

Use pull subscriptions with synchronous acknowledgment.. Pull subscriptions with synchronous acknowledgment (option B) ensure that a message is not acknowledged until the subscriber has successfully processed it. This prevents premature acknowledgment and message loss, because Cloud Pub/Sub will redeliver the message if the acknowledgment deadline expires without a synchronous ack. This is a core pattern for reliable processing.

Answer

Set a minimum number of delivery attempts.

Answer

Use message ordering.

Question 14

A company uses Cloud SQL for MySQL to store customer data. They have enabled automatic backups and a read replica for reporting. The application experiences timeouts during peak hours because the primary instance cannot handle the write load. The team needs to improve write performance without losing the ability to read from replicas. What should they do?

Accepted Answer

Increase the number of vCPUs on the primary instance.. Option C is correct because increasing the number of vCPUs on the primary Cloud SQL for MySQL instance directly improves its processing capacity to handle higher write throughput. This addresses the root cause of timeouts during peak hours without disrupting the existing read replica architecture, which continues to serve reporting queries. Cloud SQL allows vertical scaling of the primary instance by adjusting machine type, and this change does not affect the ability to read from replicas.

Answer

Increase the size of the read replica to handle writes.

Answer

Promote the read replica to a standalone instance and redirect writes.

Answer

Use Cloud Spanner instead of Cloud SQL for better write scalability.

Question 15

A company uses GKE with cluster autoscaling and node auto-upgrade. During a traffic spike, new pods are unschedulable even though the cluster autoscaler adds nodes. What is the most likely cause?

Accepted Answer

The pods have tolerations that don't match node taints. Option D is correct because if pods have tolerations that do not match the taints on the nodes, the scheduler will not place them on those nodes, even if the cluster autoscaler has added new nodes. This mismatch prevents scheduling, leading to unschedulable pods despite sufficient node capacity.

Answer

The pods have resource requests that exceed available node capacity

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The cluster autoscaler is disabled

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The node pool has reached its maximum size limit

Answer

The nodes are in unhealthy status