DEA-C01 Practice Test 15 — 15 Questions

Question 1

A data engineer is designing a data lake on Amazon S3. The data is frequently accessed by multiple analytics services, and the company needs to enforce fine-grained access control based on data tags. Which combination of AWS services should be used?

Accepted Answer

AWS Lake Formation with tag-based access control. AWS Lake Formation with tag-based access control (TBAC) is the correct choice because it provides fine-grained, attribute-based access control (ABAC) at the column, row, and cell level across a data lake on S3. By assigning LF-tags to Data Catalog resources and defining permissions based on those tags, you can enforce granular access policies that scale without managing individual user-to-resource mappings. This directly meets the requirement for tag-driven, fine-grained access for multiple analytics services.

Answer

S3 Block Public Access settings

Answer

S3 Access Points with bucket policies

Answer

S3 Object Lambda with IAM policies

Question 2

Which TWO of the following are benefits of using Amazon DynamoDB Accelerator (DAX)? (Choose TWO.)

Accepted Answer

Provides microsecond read latency. Amazon DynamoDB Accelerator (DAX) is an in-memory cache that sits between your application and DynamoDB, providing microsecond response times for read-heavy workloads. It achieves this by caching frequently accessed data in memory, reducing the latency from single-digit milliseconds to microseconds for eventually consistent reads.

Answer

Improves write throughput

Answer

Provides data durability across Availability Zones

Answer

Reduces storage costs

Question 3

A company needs to store archival logs that must be retained for 10 years. The logs are accessed infrequently, but when accessed, retrieval must occur within 12 hours. Which storage class is MOST cost-effective?

Accepted Answer

Amazon S3 Glacier Deep Archive. Option D is correct because S3 Glacier Deep Archive is the lowest-cost storage class with retrieval times within 12 hours. Option A is wrong because S3 Standard is expensive for long-term archival. Option B is wrong because S3 Intelligent-Tiering is designed for unknown access patterns, not pure archival. Option C is wrong because S3 One Zone-IA is less durable and not cost-effective for 10-year retention due to frequent access fees if retrieved.

Answer

Amazon S3 Intelligent-Tiering

Answer

Amazon S3 Standard

Answer

Amazon S3 One Zone-Infrequent Access

Question 4

A data engineer needs to migrate an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB and has a continuous stream of write operations. The migration should minimize downtime. Which AWS service should be used?

Accepted Answer

AWS Database Migration Service (DMS). Option B is correct because AWS DMS supports ongoing replication from on-premises PostgreSQL to RDS, allowing minimal downtime. Option A (S3) is for bulk data transfer. Option C (Snowball) is for offline data transfer, not for ongoing replication. Option D (Glue) is for ETL, not for database migration with replication.

Answer

AWS DataSync

Answer

AWS Snowball Edge

Answer

AWS Glue

Question 5

A company wants to use Amazon Redshift Spectrum to query data in Amazon S3. The data is in Parquet format and partitioned by date. Which step is required to enable Redshift Spectrum?

Accepted Answer

Create an external schema and external table in the AWS Glue Data Catalog.. Option A is correct because Redshift Spectrum requires an external schema and table defined in the AWS Glue Data Catalog or an external Hive metastore. Option B is wrong because the data is already in S3. Option C is wrong because loading data into Redshift is not required for Spectrum. Option D is wrong because Spectrum does not require a separate cluster.

Answer

Load the data into Redshift tables using the COPY command.

Answer

Create a separate Redshift Spectrum cluster.

Answer

Copy the data from S3 to Redshift-managed storage.

Question 6

A data engineer is designing a data store for a time-series application that requires sub-millisecond read latency for the latest data and high ingestion rates. Which AWS service is most suitable?

Accepted Answer

Amazon Timestream. Option A is correct because Amazon Timestream is a fast, scalable, serverless time-series database. Option B is wrong because Amazon RDS is not optimized for time-series workloads. Option C is wrong because Amazon DynamoDB is a key-value store, not purpose-built for time-series. Option D is wrong because Amazon ElastiCache is a caching layer, not a primary datastore for time-series.

Answer

Amazon DynamoDB

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for PostgreSQL

Question 7

Which TWO of the following are best practices for Amazon Redshift table design? (Choose TWO.)

Accepted Answer

Choose sort keys based on query patterns. Options B and D are correct. Using sort keys for query performance and distribution keys for data distribution are best practices. Option A is wrong because compression encoding should be applied, not avoided. Option C is wrong because COPY is the preferred method. Option E is wrong because distribution keys should be chosen carefully, not set to ALL by default.

Answer

Use INSERT statements for large data loads

Answer

Avoid compression encoding to reduce CPU overhead

Answer

Set distribution style to ALL for all tables

Question 8

A company is using Amazon S3 to store sensitive financial data. They need to ensure that all objects are encrypted at rest. Which TWO methods can achieve this? (Choose TWO.)

Accepted Answer

Use SSE-KMS to encrypt objects with AWS KMS.. Options A and B are correct. SSE-S3 and SSE-KMS both provide encryption at rest. Option C is wrong because client-side encryption is not managed by S3. Option D is wrong because bucket policies do not enforce encryption; they require encryption. Option E is wrong because S3 Transfer Acceleration is for speed, not encryption.

Answer

Enable S3 Transfer Acceleration on the bucket.

Answer

Apply a bucket policy that denies PutObject without encryption.

Answer

Use client-side encryption before uploading objects.

Question 9

A company uses Amazon DynamoDB for a gaming application. The table has a partition key of 'user_id' and a sort key of 'game_timestamp'. The application frequently queries by 'user_id' and filters by 'game_timestamp' within a specific date range. The queries are slow. The table has a global secondary index (GSI) on 'game_timestamp'. What is the most likely cause of the slow queries?

Accepted Answer

A hot partition exists due to uneven access pattern on 'user_id'.. Option B is correct because querying by 'user_id' using the base table is efficient, but if the GSI is being used for queries that filter by 'game_timestamp' without the partition key, the GSI may not be designed optimally. However, the stem says queries are by 'user_id' and filter by 'game_timestamp' – that should use the base table. Option A is not likely because sort key filtering is efficient. Option C (hot partition) is possible if 'user_id' distribution is skewed. Option D (GSI write capacity) doesn't affect reads. The most likely cause is a hot partition due to uneven 'user_id' distribution.

Answer

The GSI has insufficient read capacity.

Answer

The GSI is used instead of the base table for queries on 'user_id'.

Answer

The sort key is not used in the query.

Question 10

A company is using Amazon ElastiCache for Redis to cache frequently accessed data. The cache hit ratio is low, and the engineering team suspects that the eviction policy is causing important data to be removed. Which eviction policy should be used to minimize eviction of the most frequently accessed keys?

Accepted Answer

allkeys-lfu. Option D is correct because LFU (Least Frequently Used) eviction policy evicts keys that are accessed least frequently, thus preserving frequently accessed keys. Option A is wrong because allkeys-lru evicts the least recently used keys, which may remove frequently accessed keys if they are not accessed recently. Option B is wrong because volatile-lru only applies to keys with TTL. Option C is wrong because noeviction will return errors when memory is full.

Answer

allkeys-lru

Answer

noeviction

Answer

volatile-lru

Question 11

A company is designing a data lake on Amazon S3 for analytics. The data includes sensitive personally identifiable information (PII). Which TWO actions should the company take to protect the data? (Choose TWO.)

Accepted Answer

Enable S3 Block Public Access.. Options A and D are correct. Option A is correct because encrypting at rest with SSE-KMS provides encryption and key management. Option D is correct because S3 Block Public Access prevents accidental public exposure. Option B is wrong because S3 Transfer Acceleration is for speed, not security. Option C is wrong because cross-region replication does not protect data in the source bucket. Option E is wrong because Requester Pays does not control access.

Answer

Enable Requester Pays.

Answer

Enable S3 Transfer Acceleration.

Answer

Enable cross-region replication.

Question 12

A company is using Amazon RDS for MySQL and needs to reduce read latency for a global user base. Which AWS feature should be implemented?

Accepted Answer

Read Replicas. Option D is correct because Read Replicas can be promoted to stand-alone instances and reduce read latency. Option A is wrong because Multi-AZ is for high availability, not read scaling. Option B is wrong because Auto Scaling adjusts capacity, not read latency. Option C is wrong because cross-region replication latency is high.

Answer

Multi-AZ deployment

Answer

Aurora Auto Scaling

Answer

Cross-Region Replication

Question 13

A company runs a critical transactional database on Amazon RDS for PostgreSQL. They need to achieve high availability with automatic failover to a different AWS Region in case of a regional outage. Which solution meets these requirements?

Accepted Answer

Use Amazon Aurora Global Database with a primary cluster in one Region and a secondary in another.. Option D is correct because Amazon Aurora Global Database provides cross-region replication with failover capabilities. Option A is wrong because Multi-AZ only protects against AZ failures, not regional. Option B is wrong because Read Replicas are for read scaling, not automatic failover. Option C is wrong because manual snapshot restore takes too long for high availability.

Answer

Create a cross-Region Read Replica and promote it during a disaster.

Answer

Take daily automated snapshots and restore them in another Region.

Answer

Deploy the RDS instance in a Multi-AZ configuration.

Question 14

Refer to the exhibit. A data engineer configured the lifecycle policy shown. The 'logs/' prefix contains important audit logs. After 365 days, what happens to the objects?

Accepted Answer

Objects are permanently deleted.. Option D is correct because the expiration action deletes objects after 365 days. Option A is wrong because the policy transitions to Glacier, not Deep Archive. Option B is wrong because the transition to Standard IA occurs at 30 days, not 365. Option C is wrong because the transition to Glacier occurs at 90 days, not 365.

Answer

Objects are transitioned to Glacier Deep Archive.

Answer

Objects are transitioned to Glacier.

Answer

Objects are transitioned to Standard-IA.

Question 15

A company is migrating an on-premises Hadoop cluster to AWS. The data is stored in HDFS and needs to be accessible by both Amazon EMR and Amazon Redshift Spectrum. Which storage solution is most cost-effective and scalable?

Accepted Answer

Amazon Simple Storage Service (S3). Option B is correct because Amazon S3 is a cost-effective, scalable object store that can be accessed by both EMR and Redshift Spectrum. Option A is wrong because EBS is limited to a single EC2 instance. Option C is wrong because EFS is a file system, not as cost-effective for large-scale data. Option D is wrong because Amazon FSx for HDFS is designed for HDFS compatibility but is more expensive than S3.

Answer

Amazon FSx for HDFS

Answer

Amazon Elastic Block Store (EBS)

Answer

Amazon Elastic File System (EFS)