PCD Practice Test 17 — 15 Questions

Question 1

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 2

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 3

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 4

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 5

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 6

Refer to the exhibit. Which schema or index change would most improve this query?

Accepted Answer

Create a secondary index on Orders.CustomerID and Customers.CustomerID. Option C is correct because creating secondary indexes on both `Orders.CustomerID` and `Customers.CustomerID` allows Spanner to perform an index-based join without scanning the full base tables. Spanner uses distributed, strongly consistent secondary indexes to avoid full table scans, which dramatically reduces latency and resource consumption for join queries. Without these indexes, Spanner must perform a broadcast join or a full table scan on both tables, which is inefficient at scale.

Answer

Create a primary key on CustomerID

Answer

Rewrite the query as a subquery

Answer

Increase the number of Spanner nodes

Question 7

A company uses Cloud Run for a serverless application that processes user uploads. Users report that sometimes the first request after a period of inactivity takes very long (cold start). The application is stateless. They want to minimize cold start latency while keeping costs low. The application is deployed with default settings: min instances = 0, max instances = 100, CPU always off, and a container image of 1GB. What should they do to reduce cold start latency?

Accepted Answer

Set min instances to 1 to keep a warm instance.. Setting min instances to 1 ensures that at least one instance is always warm and ready to serve requests, eliminating the cold start for the first request after a period of inactivity. Since the application is stateless and the default min instances is 0, Cloud Run scales down to zero, causing a cold start on the next request. By keeping one instance warm, you minimize latency without significantly increasing cost, as you only pay for the single idle instance.

Answer

Increase container memory from the default to reduce startup time.

Answer

Use a larger container image to include more dependencies.

Answer

Enable CPU always on allocation.

Question 8

An application on Cloud Run needs to handle traffic spikes. Which configuration setting should be adjusted?

Accepted Answer

Set min and max instances. Cloud Run automatically scales the number of container instances based on incoming traffic. By setting min and max instances, you control the scaling range: a minimum ensures a baseline of warm instances to absorb sudden spikes, while a maximum caps costs and prevents resource exhaustion. This is the primary lever for handling traffic spikes in a serverless environment.

Answer

Enable HTTP/2

Answer

Increase CPU allocation

Answer

Increase memory

Question 9

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 10

A company is running a global application on Cloud Spanner. They notice high write latency on a specific table because a frequently updated row is being accessed by many clients simultaneously. Which design pattern should they implement to distribute writes across multiple nodes and reduce contention?

Accepted Answer

Add a hash suffix to the primary key of the hot row to split it into multiple rows.. Option C is correct because adding a hash suffix to the primary key of the hot row splits the single heavily contended row into multiple logical rows, each with a different primary key. This distributes the write load across multiple Cloud Spanner splits and nodes, reducing lock contention and write latency. Cloud Spanner uses a distributed, synchronous replication architecture where a single row is managed by a single split; splitting the hot row into multiple rows allows parallel writes to different splits.

Answer

Increase the number of nodes in the Cloud Spanner instance.

Answer

Use interleaved tables to co-locate related data.

Answer

Migrate the table to Cloud Bigtable which handles hotspots better.

Question 11

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 12

A company uses Cloud Spanner for a financial application. They need to ensure strong global consistency but also minimize latency for writes. What schema design should they use?

Accepted Answer

Use parent-child table relationships with interleaved tables. Option C is correct because interleaved tables in Cloud Spanner physically co-locate parent and child rows on the same split, reducing cross-node coordination for strongly consistent reads and writes. This minimizes write latency by ensuring that related data is stored together, avoiding distributed transaction overhead for operations that span parent-child relationships.

Answer

Use secondary indexes

Answer

Use commit timestamps

Answer

Use a single table with interleaved indexes

Question 13

Which two strategies should be implemented to ensure high availability for a Compute Engine instance group running a stateless web application?

Accepted Answer

Use regional managed instance group. Regional managed instance groups (MIGs) distribute instances across multiple zones within a region, providing automatic healing and high availability by recovering from zone failures. Combined with a global load balancer, they ensure traffic is routed only to healthy instances, making them ideal for stateless web applications that require resilience against zonal outages.

Answer

Use preemptible VMs

Answer

Use global load balancing

Answer

Use instance templates

Question 14

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 15

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