PDE Practice Test 2 — 10 Questions

Question 1

A company runs large batch prediction jobs on Vertex AI every day. They want to minimize costs while ensuring the jobs complete within a 4-hour window. The model requires significant memory. What is the most cost-effective approach?

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

Accepted Answer

Use preemptible VMs with a machine type that meets memory requirements. Preemptible VMs (now called Spot VMs) are significantly cheaper than standard VMs (up to 60-80% discount) and are ideal for fault-tolerant batch prediction jobs that can handle interruptions. Since the job has a 4-hour window and the model requires significant memory, using preemptible VMs with a machine type that meets the memory requirements minimizes cost while allowing the job to complete if restarted within the time limit.

Answer

Use Cloud TPUs to accelerate predictions

Answer

Use a smaller machine type (e.g., n1-standard-4) to reduce cost

Answer

Use standard VMs and reduce parallelization

Question 2

A data scientist has iterated on a model and produced a new version. The organization requires the ability to roll back to the previous version quickly if the new version performs poorly in production. Which approach should be used?

Accepted Answer

Upload both versions to Vertex AI Model Registry and use endpoint traffic splitting to route 100% to the safe version if needed.. Vertex AI Model Registry allows you to deploy multiple model versions and use endpoint traffic splitting to gradually shift traffic or instantly route 100% to a specific version. This enables immediate rollback by setting the traffic split to 100% for the previous model version without redeploying or changing infrastructure.

Answer

Store each model version in a separate Cloud Storage bucket.

Answer

Keep the previous model in a container image and redeploy via Cloud Run.

Answer

Use Cloud Source Repositories to tag model versions.

Question 3

A financial company needs to process batch trades data daily and ensure that if a transformation step fails, the entire daily run is retried from the beginning. Which design pattern is appropriate?

Accepted Answer

Use an orchestrator like Cloud Composer with retry logic. The requirement states that if any transformation step fails, the entire daily run must be retried from the beginning. An orchestrator like Cloud Composer (Apache Airflow) provides native DAG-level retry logic that can be configured to restart the entire workflow on failure, ensuring atomicity of the batch run. This pattern is essential for maintaining data consistency when partial processing cannot be tolerated.

Answer

Use idempotent writes with checkpointing

Answer

Retry the failed step only

Answer

Use a transactional staging area

Question 4

A data engineer needs to design a Bigtable row key for a time-series IoT application where each device sends data every second. The query pattern is to retrieve all data for a specific device over a time range. Which row key design minimizes hotspots?

Accepted Answer

hash(device_id)#timestamp (e.g., a3f2#2024-03-15-10:30:00). To avoid hotspots (where all writes hit a single tablet server), the row key should start with a hash of the device ID to distribute writes across the cluster, then append the timestamp for range scans.

Answer

device_id#timestamp (e.g., device123#2024-03-15-10:30:00)

Answer

timestamp#device_id (e.g., 2024-03-15-10:30:00#device123)

Answer

device_type#device_id#timestamp

Question 5

A company wants to use BigQuery to query data stored in Parquet files in Cloud Storage without loading the data into BigQuery. Which BigQuery feature should they use?

Accepted Answer

BigQuery external tables. BigQuery external tables allow querying data stored in Cloud Storage (including Parquet files) directly without loading it into BigQuery storage. This feature uses a federated query engine that reads the data on the fly, supporting formats like Parquet, Avro, ORC, CSV, and JSON. Option C is correct because it directly addresses the requirement to query Parquet files in Cloud Storage without ingestion.

Answer

BigQuery Omni

Answer

BigQuery ML

Answer

BigQuery BI Engine

Question 6

A data warehouse team uses Cloud BigQuery for analytics. They want to optimize query performance and reduce costs. Which three actions should they take? (Choose 3)

Accepted Answer

Use partitioned tables on time columns. Partitioning tables on time columns (e.g., DATE, TIMESTAMP) in BigQuery allows the query engine to perform partition pruning, scanning only the relevant partitions instead of the entire table. This directly reduces the amount of data read, lowering query costs and improving performance by limiting I/O to the necessary time range.

Answer

Use automatic reclustering

Answer

Use BI Engine for all queries

Question 7

Which TWO steps are required to deploy a custom scikit-learn model to Vertex AI for online predictions?

Accepted Answer

Save the model using joblib or pickle. Scikit-learn models must be serialized using joblib or pickle to be saved as a model artifact that can be uploaded to Vertex AI. Vertex AI's pre-built prediction containers for scikit-learn expect the model file to be in this format (typically model.joblib or model.pkl) to serve online predictions.

Answer

Write a custom prediction routine

Answer

Containerize the model using Docker

Answer

Create a Vertex AI Endpoint manually

Question 8

A company is migrating their on-premises Hadoop/Spark workloads to Google Cloud. They need a fully managed service that supports existing Spark jobs with minimal code changes, allows autoscaling, and provides integration with Cloud Storage and BigQuery. The team also wants to avoid managing cluster infrastructure and pay only for what they use. Which TWO services meet these requirements? (Choose two.)

Accepted Answer

Dataproc Serverless (Spark). Dataproc Serverless allows running Spark jobs without managing clusters, with autoscaling and pay-per-use pricing. Dataproc on GKE enables running Spark on Kubernetes with autoscaling and is fully managed. Standard Dataproc requires cluster management and is not serverless. Dataflow is for Beam, not Spark. Cloud Composer is for orchestration, not data processing.

Answer

Standard Dataproc cluster with preemptible workers

Answer

Cloud Composer with Spark

Answer

Dataflow with Spark Runner

Question 9

Your company uses Vertex AI Pipelines to automate the ML lifecycle. The pipeline includes training, evaluation, and deployment steps. You want to ensure that if a pipeline run fails due to a transient error (e.g., resource quota shortage), it automatically retries before marking the run as failed. What is the best way to implement this?

Accepted Answer

In the pipeline component code, implement retry logic using exponential backoff for specific exceptions.. Vertex AI Pipelines does not have built-in retry logic for failed steps. You can wrap each step's logic to catch transient errors and retry, or use a retry mechanism in the container itself. Kubeflow Pipelines' retry policy can be specified. Modifying pipeline code is the most direct way.

Answer

Configure Vertex AI Pipelines to automatically restart failed runs.

Answer

Set a high timeout value for the pipeline so that transient errors resolve before timeout.

Answer

Use Cloud Tasks to schedule pipeline runs and retry upon failure.

Question 10

A company stores sensitive customer data in BigQuery and Cloud Storage. They want to encrypt the data with customer-managed encryption keys (CMEK) and ensure that access to the key material is restricted to only approved networks. Which additional Google Cloud control should they implement to enforce network-based access to the encryption keys?

Accepted Answer

VPC Service Controls. VPC Service Controls (VPC-SC) can create a security perimeter around Cloud KMS and BigQuery/Cloud Storage resources, preventing data exfiltration and restricting access to approved networks. VPC-SC works with CMEK to add an extra layer of network-based access control. Cloud Armor is for HTTP(S) load balancing, IAP is for user identity, and Private Google Access is for on-premises access to public IPs.

Answer

Identity-Aware Proxy (IAP)

Answer

Private Google Access

Answer

Cloud Armor