DEA-C01 Data Store Management Practice Test 4 — 15 Questions

Question 1

A company runs a critical application on Amazon RDS for MySQL that requires a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 1 hour. The database is 500 GB. What is the MOST cost-effective disaster recovery solution that meets these requirements?

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

Accepted Answer

Use a Multi-AZ deployment with automatic failover.. Multi-AZ RDS for MySQL provides synchronous standby replication to a second Availability Zone, enabling automatic failover with minimal data loss (typically zero) and RTO under 1 hour. This meets the RPO of 5 minutes and RTO of 1 hour without manual intervention, and is more cost-effective than a cross-region replica for a 500 GB database.

Answer

Deploy the database in a single Availability Zone and perform manual point-in-time restores.

Answer

Take automated snapshots daily and store them in Amazon S3.

Answer

Create a cross-region read replica and promote it during a disaster.

Question 2

A data engineer is designing a data storage solution for IoT sensor data that is ingested at high velocity. The data is time-series and needs to be queried by time range. Which TWO AWS services are suitable for this use case? (Choose TWO)

Accepted Answer

Amazon Timestream. Amazon Timestream (C) is purpose-built as a serverless time-series database that automatically scales for high-velocity IoT ingestion and provides built-in time-range query functions, making it the most direct fit for this scenario. Amazon DynamoDB (D) is also suitable because it handles high-throughput ingestion at scale and, with its time-to-live (TTL) feature and a sort key on a timestamp attribute, supports efficient time-range queries on time-series data. Amazon RDS (A) is a relational database not optimized for high-velocity time-series ingestion or time-range querying at IoT scale. Amazon Redshift (B) is a columnar data warehouse designed for analytical queries on large historical datasets rather than high-velocity streaming ingestion. Amazon S3 (E) is object storage and lacks native time-range query capabilities, so it is not suitable as the primary store for this use case.

Answer

Amazon RDS

Answer

Amazon Redshift

Answer

Amazon S3

Question 3

A company is migrating an on-premises Apache Hadoop cluster to Amazon EMR. The cluster uses HDFS for storage. Which THREE features of Amazon EMR help reduce storage costs compared to on-premises HDFS? (Choose THREE)

Accepted Answer

Leverage Amazon S3 storage classes like S3 Standard-IA for older data.. Option D is correct because EMRFS lets EMR clusters read and write data directly in Amazon S3 instead of HDFS, so storage is decoupled from compute and you pay only for S3 usage rather than provisioning and replicating HDFS blocks across cluster nodes. Option A is correct because data stored in S3 via EMRFS can be placed in lower-cost storage classes such as S3 Standard-IA for older or infrequently accessed data, reducing the per-GB cost compared with keeping all data on HDFS. Option C is correct because EMRFS supports automatic data compression, which shrinks the amount of data stored and transferred, directly lowering S3 storage and request costs. Option B is not correct because instance store volumes are ephemeral local disks used for temporary/intermediate data, not a persistent storage-cost reduction mechanism. Option E is not correct because attaching Amazon EBS volumes provides persistent block storage for cluster nodes and typically increases cost rather than reducing it compared with S3-based storage.

Answer

Use instance store volumes for intermediate data.

Answer

Attach Amazon EBS volumes to cluster nodes for persistent storage.

Question 4

A data engineer is evaluating storage options for a new application that requires low-latency access to unstructured blobs (up to 5 TB each) with high throughput. The data will be accessed frequently for the first 30 days and then rarely. Which TWO storage solutions meet these requirements? (Choose TWO)

Accepted Answer

Amazon S3 with lifecycle policies. Option A (Amazon S3 with lifecycle policies) is correct because S3 natively stores unstructured objects up to 5 TB each, delivers low-latency, high-throughput access via parallel requests, and lifecycle policies can automatically transition objects to infrequent-access or archival classes (e.g., S3 Standard-IA, Glacier) after the 30-day frequent-access window. Option E (Amazon FSx for Lustre) is correct because it is a high-performance parallel file system designed for low-latency, high-throughput access to large unstructured datasets, and it supports linking to S3 with automated data repository tasks for tiering data that becomes rarely accessed. Option B (Amazon EBS io2 Block Express) is not appropriate because EBS provides block storage attached to a single EC2 instance, not shared access to unstructured blobs, and its 64 TiB limit and per-volume throughput make it a poor fit for blob-style, multi-client workloads. Option C (Amazon EFS) is a scalable file system but is not optimized for the extreme throughput and very large single-object sizes described, and it lacks native lifecycle tiering to cold storage classes. Option D (Amazon RDS for PostgreSQL) is a relational database service, not object/blob storage, so it cannot meet the requirement for storing 5 TB unstructured blobs with high throughput.

Answer

Amazon EBS with io2 Block Express volumes

Answer

Amazon EFS

Answer

Amazon RDS for PostgreSQL

Question 5

A company is using an RDS for PostgreSQL instance and wants to minimize downtime during a major version upgrade. Which approach should be taken?

Accepted Answer

Create a read replica of the DB instance, upgrade the replica, and then promote it to the primary instance.. Creating a read replica of the RDS for PostgreSQL instance, upgrading the replica to the new major version, and then promoting it to become the primary instance minimizes downtime by allowing the replica to be upgraded while the original primary remains fully operational. The promotion process is fast (typically seconds), and the only downtime is the brief cutover period when applications switch to the promoted replica. This approach leverages RDS's managed replication and avoids the longer downtime associated with direct in-place upgrades.

Answer

Use AWS Database Migration Service (DMS) to migrate data to a new upgraded instance.

Answer

Modify the DB instance and apply the upgrade immediately.

Answer

Take a snapshot of the DB instance and restore it as a new instance with the upgraded version.

Question 6

A data engineer is designing a data lake on Amazon S3. The data is accessed frequently for the first 30 days, then rarely after that. The engineer needs to minimize storage costs while ensuring data is available within minutes for the first 30 days and can be retrieved within 12 hours after that. Which lifecycle policy should be applied?

Accepted Answer

Transition to S3 Glacier Deep Archive after 30 days.. S3 Glacier Deep Archive offers the lowest storage cost for data that is rarely accessed after 30 days, and its retrieval time (within 12 hours) matches the requirement. The lifecycle policy transitions objects from S3 Standard (or S3 Intelligent-Tiering) to S3 Glacier Deep Archive after 30 days, minimizing costs while meeting the 12-hour retrieval window.

Answer

Transition to S3 One Zone-IA after 30 days.

Answer

Transition to S3 Standard-IA after 30 days.

Answer

Transition to S3 Glacier Flexible Retrieval after 30 days.

Question 7

A company uses DynamoDB with provisioned capacity and experiences throttling on a table during peak hours. The data engineer notices that the table has a partition key with high cardinality and the workload is read-heavy. Which action would best resolve the throttling?

Accepted Answer

Enable DynamoDB Auto Scaling for the table.. DynamoDB Auto Scaling adjusts the provisioned read capacity units (RCUs) based on actual traffic patterns, preventing throttling during peak hours without manual intervention. Since the table has high-cardinality partition keys and is read-heavy, throttling is likely due to insufficient RCUs, which Auto Scaling dynamically increases to match demand.

Answer

Switch the table to on-demand capacity mode.

Answer

Increase the provisioned write capacity units.

Answer

Add a global secondary index (GSI) to distribute reads.

Question 8

A data engineer is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 5 TB in size and has a 1 Gbps network connection. The migration must be completed within 48 hours. Which service should be used?

Accepted Answer

AWS Database Migration Service (DMS).. AWS DMS is the correct choice because it is designed for migrating databases to AWS with minimal downtime, and it can handle a 5 TB Oracle database over a 1 Gbps network within 48 hours. DMS supports ongoing replication to keep the source and target in sync, and it can use Oracle-specific features like supplemental logging and change data capture (CDC) to reduce migration time. The 1 Gbps connection provides sufficient bandwidth to transfer 5 TB in under 12 hours at full utilization, leaving ample time for setup and validation.

Answer

AWS DataSync.

Answer

Amazon S3 Transfer Acceleration.

Answer

AWS Snowball Edge.

Question 9

A company is using Amazon S3 for a data lake. The data engineer needs to ensure that all new objects are automatically encrypted with a customer-managed KMS key and that the bucket policy enforces encryption. Which THREE steps should be taken? (Choose THREE.)

Accepted Answer

Configure default encryption on the bucket to use SSE-KMS.. Option A is correct because configuring default bucket encryption with SSE-KMS ensures every newly uploaded object is automatically encrypted with AWS KMS without requiring the uploader to specify encryption headers. Option C is correct because SSE-KMS requires a KMS key, and to meet the requirement of a customer-managed key (rather than an AWS-managed key like aws/s3), the engineer must create a customer-managed KMS key and reference it in the bucket's default encryption configuration. Option B is correct because a bucket policy with a Deny effect on s3:PutObject conditioned on s3:x-amz-server-side-encryption not equaling aws:kms enforces that uploads must request SSE-KMS encryption, preventing unencrypted or SSE-S3 uploads. Option D is not correct because lifecycle policies transition, expire, or delete objects and cannot retroactively apply encryption to existing objects. Option E is not correct because CloudTrail records API activity for auditing but does not enforce or apply encryption to objects.

Answer

Use a lifecycle policy to apply encryption to existing objects.

Answer

Enable AWS CloudTrail to monitor encryption.

Question 10

A company uses Amazon RDS for MySQL with Multi-AZ deployment. The primary instance fails, and automatic failover occurs. After failover, the data engineer notices that the new primary instance has a different DNS endpoint. Which TWO statements are true about this scenario? (Choose TWO.)

Accepted Answer

The DNS CNAME record is updated to point to the new primary.. Option C is correct because in an Amazon RDS Multi-AZ failover, RDS automatically updates the DNS CNAME record for the DB instance's endpoint so that it resolves to the IP address of the newly promoted standby instance. Option E is correct because applications should always connect using the stable DB instance endpoint (the DNS name), which remains the same after failover, so no application-side endpoint change is needed. Option A is incorrect because the standby is created in a different Availability Zone from the primary to provide high availability. Option B is incorrect because the DNS update is automatic, not manual. Option D is incorrect because the endpoint name does not change to the standby's endpoint; the same endpoint now points to the promoted instance.

Answer

The standby instance is created in the same Availability Zone as the failed primary.

Answer

A manual DNS update is required to connect to the new primary.

Answer

The endpoint changes to the standby instance's endpoint.

Question 11

Refer to the exhibit. A data engineer is troubleshooting write throttling on the Orders table. The table has a composite primary key (OrderID as partition key, CustomerID as sort key). The engineer notices that writes are throttled even though the write capacity is not fully utilized. What is the most likely cause?

Accepted Answer

Writes are concentrated on a single partition key value.. D is correct because write throttling on an Amazon DynamoDB table occurs when requests exceed the provisioned throughput for a specific partition, even if the overall table write capacity is underutilized. With a composite primary key where OrderID is the partition key, writes concentrated on a single OrderID value (e.g., a hot key) will hit that partition's 3,000 WCU or 1,000 WCU (on-demand) limit, causing throttling while other partitions remain idle.

Answer

The table is empty and has no items.

Answer

A global secondary index (GSI) is consuming write capacity.

Answer

The read capacity units are too low.

Question 12

A company wants to store historical financial data for 7 years with immediate access for the first year and then infrequent access. After 7 years, the data must be automatically deleted. Which S3 lifecycle policy should be configured?

Accepted Answer

Transition to S3 Glacier Deep Archive after 365 days, expire after 2555 days. It meets all requirements: immediate access for the first year (no transition before 365 days), then transition to S3 Glacier Deep Archive for infrequent access and cost savings, with automatic deletion after 7 years (2555 days). S3 Glacier Deep Archive is the most cost-effective storage class for long-term archival data that is rarely accessed, and the 2555-day expiration ensures compliance with the 7-year retention policy.

Answer

Transition to S3 Standard-IA after 30 days, expire after 2555 days

Answer

Transition to S3 Glacier Flexible Retrieval after 365 days, expire after 2555 days

Answer

Transition to S3 One Zone-IA after 90 days, expire after 365 days

Question 13

A data engineer is designing a data store for real-time analytics on high-velocity clickstream data. The data must be stored in a schema-on-read format and support SQL queries with sub-second latency. Which service should be used?

Accepted Answer

Amazon Kinesis Data Firehose to S3 with Athena. Amazon Kinesis Data Firehose can ingest high-velocity clickstream data and deliver it to Amazon S3, where it is stored in a schema-on-read format (e.g., Parquet or ORC). Amazon Athena then allows SQL queries directly on the data in S3 with sub-second latency when using partitions, columnar formats, and optimizations like AWS Glue Catalog. This combination meets the requirements for real-time analytics without predefining a schema.

Answer

Amazon Redshift

Answer

Amazon Kinesis Data Analytics

Answer

Amazon DynamoDB

Question 14

A company has an S3 bucket with millions of objects. The data engineer needs to identify which objects are not accessed for 90 days to move them to a lower-cost storage class. Which feature should be used?

Accepted Answer

S3 Storage Class Analysis. S3 Storage Class Analysis (SCA) is the correct feature because it monitors access patterns across objects and provides recommendations for transitioning data to lower-cost storage classes based on last-access dates. SCA can analyze objects that have not been accessed for 90 days and generate a report to inform lifecycle policy creation, directly addressing the requirement to identify objects for cost optimization.

Answer

S3 Inventory

Answer

S3 Server Access Logs

Answer

S3 Event Notifications

Question 15

Which TWO statements are true about Amazon S3 bucket policies and ACLs?

Accepted Answer

ACLs are a legacy access control mechanism that is still supported.. Option B is correct because S3 ACLs are indeed a legacy access control mechanism that AWS still supports for backward compatibility, though AWS recommends disabling ACLs (Object Ownership set to Bucket owner enforced) for new buckets. Option E is correct because S3 bucket policies are resource-based policies that include a Principal element, allowing you to grant cross-account access to IAM users or roles in other AWS accounts (the other account's identity must also have an identity-based policy allowing the action). Option A is incorrect because S3 does not evaluate bucket policies before ACLs in a strict ordered sequence; access is granted if any applicable policy or ACL allows it (with explicit deny in a bucket policy overriding), so the statement mischaracterizes how the two mechanisms interact. Option C is incorrect because ACLs grant permissions only to specific AWS accounts or predefined S3 groups (such as Authenticated Users group, All Users, or Log Delivery), not as a general grant to 'all authenticated AWS users' in the way described. Option D is incorrect because ACLs are simple grants of READ, WRITE, READ_ACP, WRITE_ACP permissions and do not support condition keys such as IP address restrictions; conditions like aws:SourceIp are only available in bucket policies.

Answer

When both exist, bucket policies are evaluated before ACLs.

Answer

ACLs can grant permissions to all authenticated AWS users.

Answer

ACLs support conditions such as IP address restrictions.