Google PCA Practice Test 24 — 15 Questions

Question 1

A company needs to store petabytes of time-series IoT sensor data and query it with single-digit millisecond latency at millions of reads per second. The data has a simple key-value structure with timestamps. Which Google Cloud database is MOST appropriate?

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

Accepted Answer

Cloud Bigtable. Cloud Bigtable is designed for petabyte-scale, low-latency, high-throughput NoSQL storage for time-series, IoT, and financial data. It scales horizontally by adding nodes. BigQuery is an analytics warehouse with seconds-to-minutes latency, Cloud SQL is for OLTP with limited QPS, and Firestore is for document data with hierarchical structure.

Answer

BigQuery

Answer

Firestore

Answer

Cloud Spanner

Question 2

A team wants to define an SLO for a service that requires 99.9% availability over a 30-day window. They need to measure the ratio of successful requests to total requests. Which SLI should they use?

Accepted Answer

Request success rate. An SLI is a measure of service performance. For availability, the standard SLI is the proportion of successful requests (e.g., HTTP 2xx) to total requests. Latency SLI measures response times. Error budget is derived from SLO. SRE is the practice.

Answer

SRE

Answer

Request latency

Answer

Error budget

Question 3

A company runs a Bigtable instance for real-time analytics. They notice increasing latency for point reads. The row key pattern is 'YYYYMMDD_userID_productID'. The team suspects read hotspots. Which row key design change would BEST distribute the load across tablets?

Accepted Answer

Reorder to 'userID_productID_YYYYMMDD'. Using a field prefix (like user ID) before the timestamp distributes reads across tablets because Bigtable orders rows lexicographically. If the timestamp is first, recent data falls into a single tablet, causing hotspots. Reversing the timestamp or hashing the row key are also common strategies. Salting with a random prefix is another approach.

Answer

Prepend a random number field: 'random_YYYYMMDD_userID_productID'

Answer

Keep the same order but use a shorter timestamp: 'YYMMDD_userID_productID'

Answer

Reverse the timestamp: 'DDMMYYYY_userID_productID'

Question 4

A team wants to provide a consistent, low-latency experience for global users accessing static content (images, CSS, JS) hosted on Cloud Storage. They also need to be able to invalidate cached content quickly when updates occur. Which service should they use?

Accepted Answer

Cloud CDN. Cloud CDN caches content at edge locations for low latency. Cache invalidation allows purging updated content, which is essential for static assets.

Answer

Cloud NAT

Answer

Cloud Load Balancing with backend bucket

Answer

Cloud Storage transfer service

Question 5

A company runs a batch processing job that uses preemptible VMs. The job occasionally fails due to VM preemption. They want to improve reliability without significantly increasing cost. Which TWO actions should they take? (Choose TWO.)

Accepted Answer

Use a managed instance group with autoscaling and preemptible VMs. Using a managed instance group (MIG) with autoscaling and preemptible VMs can automatically recreate instances if preempted. Implementing a retry logic in the application to re-run failed tasks also improves reliability. Using sole-tenant nodes or adding more nodes increases cost or complexity. Switching to regular VMs increases cost.

Answer

Use sole-tenant nodes to reduce risk of preemption

Answer

Switch to regular (non-preemptible) VMs

Answer

Increase the number of preemptible VMs

Question 6

A company is moving a legacy application to Compute Engine. The application has inconsistent resource usage and the team wants to optimise costs without performance degradation. They are evaluating committed use discounts (CUDs) and other discount types. Which THREE statements are correct about CUDs? (Choose 3)

Accepted Answer

Spend-based CUDs are applied automatically to all eligible projects in the billing account. CUDs offer discounts for 1-year or 3-year commitments. Resource-based CUDs apply to specific machine types in a region. Spend-based CUDs apply to total compute spend. CUDs can be combined with sustained use discounts, but sustained use discounts are automatic and not required to be purchased.

Answer

CUDs require a minimum of 10 instances to qualify

Answer

CUDs cannot be combined with sustained use discounts

Question 7

A company wants to improve the performance of their Cloud SQL for PostgreSQL instance. They notice many idle connections and slow queries. Which THREE actions could help? (Choose 3)

Accepted Answer

Add appropriate indexes. PgBouncer reduces connection overhead. Read replicas offload read queries. Adding indexes speeds up queries. Private IP improves security and latency but not performance. Increasing disk size helps if I/O bottleneck, but not connection or query performance.

Answer

Enable private IP

Answer

Increase disk size

Question 8

An application running on Compute Engine frequently makes connection requests to a Cloud SQL for PostgreSQL instance. The connections are short-lived and many are created per second. What should be implemented to reduce latency and connection overhead?

Accepted Answer

Deploy PgBouncer on the application server or as a sidecar. Connection pooling reuses database connections instead of creating new ones for each request. PgBouncer is a lightweight connection pooler for PostgreSQL. Cloud SQL Auth Proxy is for secure connections but does not pool.

Answer

Increase the number of vCPUs on the Cloud SQL instance

Answer

Enable connection scaling in Cloud SQL

Answer

Use Cloud SQL Auth Proxy with private IP

Question 9

A company is designing a disaster recovery strategy for a critical application. They need to ensure that if the primary region fails, the application can fail over to a secondary region with a Recovery Point Objective (RPO) of 1 hour and a Recovery Time Objective (RTO) of 15 minutes. The application uses Cloud Spanner. Which Cloud Spanner configuration meets these requirements?

Accepted Answer

Multi-region configuration (e.g., nam3). Cloud Spanner multi-region configurations provide automatic replication across regions with synchronous replication, achieving RPO near zero and RTO in seconds. Single-region configurations do not provide geographic failover. A two-region setup like nam3 (US Central + US East) or eur3 (Europe) provides synchronous replication with strong consistency. Active/active is the default. Multi-region configs are recommended for DR.

Answer

Single-region configuration

Answer

Backup and restore in another region

Answer

Dual-region with asynchronous replication

Question 10

A company is adopting Site Reliability Engineering (SRE) practices. After a major incident, they want to conduct a review to understand what went wrong and how to prevent recurrence, without blaming individuals. Which SRE practice should they follow?

Accepted Answer

Conduct a blameless postmortem. A blameless postmortem focuses on learning from incidents without assigning blame. Error budgets are for measuring reliability, SLOs/SLIs are for defining targets, and capacity planning is for scaling.

Answer

Define SLOs and SLIs

Answer

Create an error budget policy

Answer

Perform capacity planning

Question 11

A company wants to migrate 200 TB of on-premises file shares to Cloud Storage. The network is slow (50 Mbps) and the project is time-sensitive. Which THREE services should they use? (Choose 3)

Accepted Answer

Transfer Appliance. Transfer Appliance is for large data shipping. Storage Transfer Service can transfer from another cloud or on-prem (if intermediate). Migrate for Compute Engine is for VMs only. Database Migration Service is for databases. gsutil is for direct upload but slow.

Answer

Database Migration Service

Answer

Migrate for Compute Engine

Question 12

A company uses Cloud SQL for PostgreSQL and experiences connection spikes that cause connection limits to be exceeded. They need a solution to manage connection pooling. Which approach should they take?

Accepted Answer

Configure PgBouncer on a separate Compute Engine instance to pool connections. Cloud SQL Auth Proxy handles authentication and encryption, but not pooling. PgBouncer is a lightweight connection pooler for PostgreSQL. Cloud SQL does not natively support ProxySQL for PostgreSQL. Scaling up vCPUs increases connection limits but does not pool connections efficiently.

Answer

Use ProxySQL to pool connections

Answer

Increase the number of vCPUs on the Cloud SQL instance

Answer

Use Cloud SQL Auth Proxy with connection pooling enabled

Question 13

A company has a Bigtable instance handling time-series data. Write throughput is below expectations and latency is high. The row key format is `userid_timestamp`. Which row key design change would MOST improve performance?

Accepted Answer

Use a hash of the userid as the row key prefix. Bigtable performance relies on distributing writes across tablets. A row key with a high-cardinality prefix (e.g., hashed userid) avoids hotspots. A timestamp prefix causes all writes to go to the last tablet (hotspot). Reversing timestamp helps but still not as good as hashing. Adding column families does not affect row key distribution.

Answer

Use `timestamp_userid` without reversal

Answer

Add more column families to store different metrics

Answer

Reverse the timestamp and use `timestamp_userid`

Question 14

A company wants to reduce costs for their steady-state Compute Engine workloads. They have 10 n1-standard-4 VMs running 24/7. Which TWO actions will reduce costs? (Choose 2)

Accepted Answer

Purchase committed use discounts (1-year) for the VMs. Committed use discounts provide significant savings (up to 70%) for steady-state workloads. Right-sizing recommendations help identify if VMs are over-provisioned, allowing downsizing. Preemptible VMs are for interruptible workloads; sustained use is automatic but less savings.

Answer

Use preemptible VMs

Answer

Migrate to sole-tenant nodes

Answer

Enable sustained use discounts

Question 15

An organization runs a critical application on Compute Engine with a 99.99% SLO. They have set an error budget of 0.01% over a 30-day window. Recently, an unexpected traffic spike caused a 0.005% error rate for a few hours. Which THREE actions align with SRE best practices? (Choose 3)

Accepted Answer

Conduct a blameless postmortem to understand the root cause and prevent recurrence.. SRE best practices include using error budgets to drive decisions, conducting blameless postmortems, and adjusting capacity based on usage. Relying on past data and ignoring the spike is not proactive.

Answer

Immediately rollback any recent changes to prevent further errors.

Answer

Disable monitoring alerts for the error rate to avoid false alarms.