10 beginner questions on the DEA-C01 domains: data ingestion and transformation (streaming, file formats, orchestration), data store management (catalogs, warehouses, S3 lifecycle), data operations and support (querying and monitoring), and data security and governance.

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  1. A data engineer runs Amazon Athena queries on large CSV files in Amazon S3 and wants faster queries that read less data. Which change helps most?

    • A. Convert the data to a columnar format such as Apache Parquet ✔ correct
    • B. Convert the data to JSON so each record is self-describing
    • C. Move the files to the S3 Glacier Deep Archive storage class
    • D. Split every column into its own separate CSV file by hand

    Answer: A. Columnar formats such as Parquet and ORC compress by column and let Athena read only the columns and blocks a query needs, which improves performance. JSON is row-based and larger; archived objects cannot be queried directly.

    Source: docs.aws.amazon.com/athena/latest/ug/columnar-storage.html · Domain: Data Ingestion and Transformation

  2. A company wants to collect website clickstream events continuously and process them within seconds of arrival. Which service is built for this kind of real-time ingestion?

    • A. AWS DataSync
    • B. Amazon Kinesis Data Streams ✔ correct
    • C. AWS Glue DataBrew
    • D. Amazon S3 Glacier

    Answer: B. Kinesis Data Streams collects and processes large streams of data records in real time, such as clickstreams and logs. DataSync moves files in bulk, and Glue DataBrew is a visual data preparation tool.

    Source: docs.aws.amazon.com/streams/latest/dev/introduction.html · Domain: Data Ingestion and Transformation

  3. A pipeline must run an AWS Glue job, then two AWS Lambda functions, with retries and a branch on failure, without managing servers. Which service orchestrates this workflow?

    • A. Amazon SNS
    • B. Amazon Athena
    • C. AWS Step Functions ✔ correct
    • D. AWS Snowball

    Answer: C. AWS Step Functions is a serverless orchestration service that runs workflows as a series of steps with built-in retries, error handling and branching. SNS only sends notifications; Athena runs SQL queries.

    Source: docs.aws.amazon.com/step-functions/latest/dg/welcome.html · Domain: Data Ingestion and Transformation

  4. New datasets land in Amazon S3 every day. Which feature scans the data, infers its schema and creates or updates table definitions in the AWS Glue Data Catalog?

    • A. An Athena workgroup
    • B. An S3 Lifecycle rule
    • C. An AWS Glue job bookmark
    • D. An AWS Glue crawler ✔ correct

    Answer: D. A Glue crawler connects to a data store, uses classifiers to infer format and schema, and writes table metadata to the Data Catalog. Job bookmarks only track data a Glue job already processed; Lifecycle rules move or expire objects; Athena workgroups separate query workloads.

    Source: docs.aws.amazon.com/glue/latest/dg/add-crawler.html · Domain: Data Store Management

  5. An S3 Lifecycle configuration can automatically transition objects to a lower-cost storage class, such as S3 Standard-IA, after a set number of days.

    • A. True ✔ correct
    • B. False

    Answer: A. True. Lifecycle transition actions move objects to another storage class on a schedule, and expiration actions delete them. This lowers storage cost for data that is accessed less often as it ages.

    Source: docs.aws.amazon.com/AmazonS3/latest/userguide/object-lifecycle-mgmt.html · Domain: Data Store Management

  6. A company needs a fully managed data warehouse to run complex SQL analytics over petabytes of structured data. Which service fits best?

    • A. Amazon DynamoDB
    • B. Amazon Redshift ✔ correct
    • C. Amazon ElastiCache
    • D. Amazon Neptune

    Answer: B. Amazon Redshift is a fully managed, petabyte-scale data warehouse for SQL analytics. DynamoDB is a key-value and document database, ElastiCache is an in-memory cache, and Neptune is a graph database.

    Source: docs.aws.amazon.com/redshift/latest/mgmt/welcome.html · Domain: Data Store Management

  7. An analyst wants to run ad hoc SQL queries directly on data stored in Amazon S3, without loading it into a database or managing any servers. Which service should they use?

    • A. Amazon DynamoDB
    • B. Amazon Data Firehose
    • C. Amazon Athena ✔ correct
    • D. AWS DataSync

    Answer: C. Athena is a serverless, interactive query service that analyzes data in S3 with standard SQL. Data Firehose delivers streaming data to destinations, and DataSync transfers files; neither runs SQL queries.

    Source: docs.aws.amazon.com/athena/latest/ug/what-is.html · Domain: Data Operations and Support

  8. Which two services can a data engineer use to monitor AWS Glue jobs and react automatically when a job fails? (Select TWO)

    • A. Amazon CloudWatch ✔ correct
    • B. Amazon EventBridge ✔ correct
    • C. Amazon Macie
    • D. AWS Snowball
    • E. Amazon Lex

    Answer: A, B. Glue publishes metrics and logs to CloudWatch, and job state-change events can trigger EventBridge rules (for example, to send an alert). Macie finds sensitive data, Snowball moves data offline and Lex builds chatbots.

    Source: docs.aws.amazon.com/glue/latest/dg/monitor-glue.html · Domain: Data Operations and Support

  9. A company's data lake tables are registered in the AWS Glue Data Catalog. Analysts must see only some columns of a sales table when they query it with Athena. Which service manages these fine-grained permissions?

    • A. AWS Key Management Service
    • B. Amazon Inspector
    • C. Amazon GuardDuty
    • D. AWS Lake Formation ✔ correct

    Answer: D. Lake Formation enforces column-, row- and cell-level permissions on Data Catalog tables across services such as Athena and Redshift Spectrum. KMS manages encryption keys, not column access; GuardDuty detects threats.

    Source: docs.aws.amazon.com/lake-formation/latest/dg/what-is-lake-formation.html · Domain: Data Security and Governance

  10. Before sharing an S3 bucket with analysts, a team must find objects that contain personally identifiable information (PII). Which service discovers this kind of sensitive data?

    • A. Amazon Macie ✔ correct
    • B. AWS Config
    • C. Amazon Athena
    • D. AWS Glue DataBrew

    Answer: A. Amazon Macie uses machine learning and pattern matching to discover sensitive data such as PII in Amazon S3 and reports findings. AWS Config records resource configuration changes; it does not inspect object contents.

    Source: docs.aws.amazon.com/macie/latest/user/what-is-macie.html · Domain: Data Security and Governance

Original practice questions written by xOps School (DevOpsSchool Private Limited) from the public AWS exam objectives (DEA-C01 exam guide version 1.1 (2025-12-12)), checked 2026-10-25. They are not actual exam questions. xOps School is not affiliated with or endorsed by AWS; exam names are trademarks of their owners. Official exam page: docs.aws.amazon.com/aws-certification/latest/data-engineer-associate-0.

Last modified: Sunday, 25 October 2026, 9:57 PM