DBS-C01 Practice Test 30 — 15 Questions

Question 1

A company needs to build a reporting dashboard that queries a large dataset stored in Amazon S3. The queries are complex and require full SQL support. Which service should be used?

Accepted Answer

Amazon Athena. Amazon Athena is the correct choice because it is a serverless, interactive query service that allows you to analyze data directly in Amazon S3 using standard SQL. It supports complex queries, including joins, window functions, and CTEs, and requires no infrastructure management, making it ideal for ad-hoc reporting on large datasets in S3.

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Amazon Redshift Spectrum

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Amazon RDS

Answer

Amazon DynamoDB

Question 2

A developer is troubleshooting an application that uses Amazon DynamoDB. The application sometimes receives ProvisionedThroughputExceededException errors. The table has on-demand capacity mode. The errors occur in short bursts. What is the most likely cause?

Accepted Answer

The request rate exceeds the partition's throughput capacity in a short burst.. In on-demand capacity mode, DynamoDB automatically scales to handle traffic, but it still has per-partition throughput limits. If a short burst of requests exceeds the partition's capacity, ProvisionedThroughputExceededException can occur even in on-demand mode. This is because on-demand tables are subject to the same partition-level limits as provisioned tables, and sudden spikes may not be instantly absorbed. The other options are incorrect because on-demand mode does not have provisioned throughput limits (A, C) and GSIs have their own throughput but the error is on the table (B).

Answer

The table has a low read/write capacity mode limit that needs to be increased.

Answer

The global secondary index (GSI) has a different throughput limit.

Answer

The table has reached the maximum provisioned throughput.

Question 3

A company wants to ensure that only specific IAM users can perform certain operations on an Amazon RDS DB instance, such as creating snapshots or modifying the instance. Which AWS feature should be used to define these permissions?

Accepted Answer

IAM policies. IAM policies are the AWS feature used to define permissions for IAM users, groups, and roles, specifying what actions they can perform on which resources. For RDS, you can create IAM policies that allow or deny specific operations like rds:CreateDBSnapshot or rds:ModifyDBInstance, and attach them to IAM users or roles. This provides fine-grained access control to RDS management operations.

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VPC security groups

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DB parameter groups

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DB subnet groups

Question 4

A company has an Amazon DynamoDB table with on-demand capacity. Users report that write requests are occasionally throttled during peak hours. The application uses the AWS SDK and retries with exponential backoff. Which monitoring approach should be used to identify the cause of throttling?

Accepted Answer

Monitor CloudWatch metrics for ThrottledRequests and ConsumedWriteCapacityUnits.. CloudWatch metrics such as ThrottledRequests and ConsumedWriteCapacityUnits directly indicate throttling events and capacity usage, enabling identification of throttling causes even with on-demand capacity. Option A is incorrect because AWS CloudTrail logs API calls but does not provide detailed throttling metrics at the item level. Option B is incorrect because VPC Flow Logs capture network traffic, not database-level throttling. Option D is incorrect because DynamoDB Streams capture item-level changes, not throttling events.

Answer

Use AWS CloudTrail to monitor PutItem API calls for throttling errors.

Answer

Analyze VPC Flow Logs to check for network congestion.

Answer

Enable DynamoDB Streams and process records to monitor throttled requests.

Question 5

A company is using Amazon DynamoDB to store session data for a web application. The session data expires after 24 hours. Which DynamoDB feature should the company use to automatically delete expired items?

Accepted Answer

DynamoDB Time to Live (TTL). DynamoDB Time to Live (TTL) is the correct choice because it provides a cost-effective, fully managed mechanism to automatically delete expired items based on a timestamp attribute in the table. TTL works by comparing the current time to the epoch time value stored in the designated TTL attribute; when the value is in the past, DynamoDB marks the item for deletion, typically within 48 hours. This eliminates the need for custom code or additional AWS services, directly addressing the requirement to remove session data after 24 hours.

Answer

A retention policy on the DynamoDB table

Answer

DynamoDB Streams

Answer

A scheduled AWS Lambda function that scans and deletes expired items

Question 6

Which THREE considerations are important when designing a database for a global, multi-Region application using Amazon DynamoDB Global Tables? (Select THREE.)

Accepted Answer

Application tolerance for eventually consistent reads. Option C is correct because DynamoDB Global Tables replicate writes asynchronously across Regions, so reads in a replica Region are only eventually consistent and the application must tolerate that behavior. Option D is correct because each replica table in a Global Table has its own provisioned write capacity (or on-demand mode), so write capacity must be sufficient in every Region to handle that Region's writes and replicated writes. Option E is correct because DynamoDB Global Tables use a last-writer-wins conflict resolution mechanism based on timestamps to reconcile concurrent updates to the same item across Regions. Option A is not required, since Global Tables are designed for multi-Region active-active writes, not a single write Region. Option B is not valid, because strongly consistent reads are not supported across Regions in Global Tables; only eventually consistent reads are available on replicas.

Answer

Using a single write region to avoid conflicts

Answer

Strongly consistent reads across regions

Question 7

A company is using Amazon Aurora MySQL and needs to audit all database logins and query activity. Which feature should be enabled to meet this requirement?

Accepted Answer

Enable Advanced Auditing through the DB cluster parameter group by setting the server_audit_logging parameter and related parameters.. Amazon Aurora MySQL's Advanced Auditing feature, enabled by setting the server_audit_logging parameter and related parameters in the DB cluster parameter group, captures all database logins and query activity. Option A (audit_log_enabled) is a different, less detailed audit log feature, not the full advanced auditing. Option B (Enhanced Monitoring) monitors OS-level metrics, not database activity. Option C (CloudTrail) logs AWS API calls, not database queries.

Answer

Enable database audit logs by setting the audit_log_enabled parameter to 1.

Answer

Enable RDS Enhanced Monitoring.

Answer

Enable AWS CloudTrail to log database queries.

Question 8

A company has an Amazon RDS for MySQL DB instance that stores sensitive customer data. The security team requires that all data at rest be encrypted using a customer-managed AWS KMS key. The DB instance was originally launched without encryption. Which combination of steps will meet the requirement with the least downtime?

Accepted Answer

Take a snapshot of the DB instance, copy the snapshot with encryption enabled using the desired KMS key, and restore the encrypted snapshot to a new DB instance.. RDS does not support enabling encryption in place on an existing unencrypted instance. The supported path is to snapshot the instance, copy the snapshot with encryption enabled using the customer-managed KMS key, and restore that encrypted snapshot as a new DB instance. This achieves encryption at rest with minimal downtime because the source keeps running until cutover.

Answer

Create a read replica of the DB instance with encryption enabled, and then promote the read replica to become the primary instance.

Answer

Modify the DB instance and enable encryption using the AWS Management Console.

Answer

Take a snapshot of the DB instance, copy the snapshot with encryption enabled, and restore the encrypted snapshot to the same DB instance ID.

Question 9

A company is building a mobile application that requires users to be able to query their order history quickly. The data is stored in Amazon DynamoDB, and each user has up to 10,000 orders over time. The application needs to support pagination and filtering by order date. What is the MOST efficient way to model this data in DynamoDB?

Accepted Answer

Use user ID as the partition key and order date as the sort key. Using user ID as the partition key ensures all orders for a user are co-located on a single partition, enabling efficient queries. Adding order date as the sort key allows the application to filter and paginate by date range using the Query API with KeyConditionExpression, which is far more efficient than scanning or using a secondary index.

Answer

Scan the entire table and filter on user ID

Answer

Store all orders as a JSON document in a single item per user

Answer

Use user ID as the partition key and a Global Secondary Index on order date

Question 10

A database administrator needs to monitor the number of connections to an Amazon RDS for MySQL DB instance. Which Amazon CloudWatch metric should be used?

Accepted Answer

DatabaseConnections. The DatabaseConnections metric in Amazon CloudWatch for RDS for MySQL reports the number of client connections currently open to the DB instance. This is the standard metric provided by RDS for monitoring connection counts, and it directly answers the requirement to monitor the number of connections. It is available at 1-minute granularity by default and can be used to set alarms for connection thresholds.

Answer

NetworkThroughput

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ConnectionAttempts

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ActiveTransactions

Question 11

A team is migrating an on-premises Microsoft SQL Server database to AWS. The database is used for reporting and analytics, with complex queries that join multiple tables. The team wants to minimize application changes and ensure compatibility. Which AWS service should they use?

Accepted Answer

Amazon RDS for SQL Server. Amazon RDS for SQL Server is the correct choice because it provides a managed SQL Server database engine that is fully compatible with on-premises SQL Server, minimizing application changes. The service supports complex queries with joins and reporting workloads without requiring code modifications, as it uses the same T-SQL dialect and features.

Answer

Amazon RDS for MySQL

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Amazon Redshift

Answer

Amazon DynamoDB

Question 12

A company is running an Oracle database on Amazon RDS with the configuration shown in the exhibit. The application is experiencing high latency for write operations. The storage is consistently showing high queue depth and write latency. Which change will most improve write performance?

Accepted Answer

Migrate to io1 or io2 storage with higher provisioned IOPS.. Migrating to io1 or io2 block storage with higher provisioned IOPS directly addresses the root cause of high queue depth and write latency. Unlike gp2, which has a baseline IOPS of 3 per GB (up to 16,000 IOPS at 5,334 GB) and a burst bucket that depletes under sustained load, io1/io2 provide consistent, provisioned IOPS independent of volume size. This ensures the storage subsystem can keep up with the write workload, reducing queue depth and latency.

Answer

Increase allocated storage to 1,000 GB to get higher gp2 baseline IOPS.

Answer

Enable storage auto scaling and increase storage throughput to 500 MB/s.

Answer

Change the DB instance class to db.r5.2xlarge.

Question 13

A financial services company uses Amazon DynamoDB to store transaction records. The security team requires that all items be encrypted at rest using a customer-managed AWS KMS key. Additionally, the company must be able to audit key usage and rotation. What is the MOST secure and auditable approach?

Accepted Answer

Use SSE-KMS with a customer-managed key, enable automatic key rotation, and enable CloudTrail data events for the key.. Using a customer-managed KMS key with automatic annual rotation and enabling CloudTrail logging of key usage provides encryption control and auditing. Option A is wrong because SSE-S3 does not provide customer control or audit. Option B is wrong because manual rotation is less secure and auditable than automatic rotation. Option D is wrong because client-side encryption would require managing encryption keys on the client side, which does not leverage the AWS KMS infrastructure for automatic key rotation and auditing, and is not as integrated or auditable as server-side encryption with KMS.

Answer

Enable default encryption on the DynamoDB table using SSE-S3.

Answer

Use SSE-KMS with a customer-managed key and manually rotate the key every 90 days.

Answer

Use client-side encryption with the AWS Encryption SDK.

Question 14

A security team is investigating a potential data breach in an Amazon RDS for SQL Server database. They need to determine which user executed a specific DELETE statement at a particular time. What should they do?

Accepted Answer

Enable audit logs for the RDS instance and send them to CloudWatch Logs.. Enabling audit logs for the RDS for SQL Server instance captures detailed SQL statement execution, including the users and timestamps. Sending these logs to CloudWatch Logs allows for easy searching and alerting. Option B is correct because it directly addresses the need to identify the user who executed a specific SQL statement. Option A is incorrect because AWS CloudTrail logs API actions (e.g., creating or modifying RDS instances), not SQL queries. Option C is incorrect because VPC Flow Logs capture network traffic metadata, not database-level activity. Option D is incorrect because AWS Trusted Advisor provides best-practice checks and does not offer fine-grained auditing.

Answer

Enable AWS CloudTrail for the RDS instance.

Answer

Enable VPC Flow Logs for the database subnet.

Answer

Enable AWS Trusted Advisor.

Question 15

A company is designing a database for an IoT application that ingests millions of sensor readings per second. Each reading includes device ID, timestamp, and measurement. The workload requires time-series analytics and data retention for 90 days. Which AWS database solution is MOST appropriate?

Accepted Answer

Amazon Timestream. Amazon Timestream is a purpose-built time-series database designed for IoT and operational applications that ingest millions of sensor readings per second. It automatically manages data retention policies (e.g., 90 days) by storing recent data in memory and historical data in a cost-optimized store, and it supports time-series analytics with built-in functions like interpolation and smoothing.

Answer

Amazon Redshift with auto-copy from S3

Answer

Amazon ElastiCache for Redis with time-series module

Answer

Amazon DynamoDB with TTL