DBS-C01 Practice Exam 57 — 20 Questions

Question 1

A developer is deploying an application that uses Amazon DynamoDB as its database. The application experiences sudden spikes in traffic. Which DynamoDB feature should the developer use to handle the spikes without manual intervention?

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

Accepted Answer

DynamoDB auto scaling. DynamoDB auto scaling (option C) is the correct choice because it automatically adjusts the provisioned read and write capacity based on actual traffic patterns using the AWS Application Auto Scaling service. This allows the application to handle sudden spikes in traffic without manual intervention by increasing capacity when utilization rises and decreasing it when traffic subsides, all while maintaining a target utilization percentage.

Answer

DynamoDB Accelerator (DAX)

Answer

DynamoDB on-demand capacity mode

Answer

DynamoDB global tables

Question 2

A company is using Amazon DynamoDB with auto scaling for a social media application. The table has a partition key of 'user_id'. The application performs many small writes (update user profile) and reads (fetch user profile). Recently, the application's response time has increased. The DBA checks CloudWatch and sees that 'ConsumedWriteCapacityUnits' is close to 'ProvisionedWriteCapacityUnits', and 'WriteThrottleEvents' is low. However, 'ReadThrottleEvents' is high. The table has 1000 WCU and 1000 RCU provisioned. The auto scaling is configured to add capacity when utilization exceeds 70%. The DBA also notices that 'ReadThrottleEvents' spikes during peak hours. What should the DBA do to reduce read throttling?

Accepted Answer

Increase the provisioned read capacity to 2000 RCU or implement DAX caching.. Increasing provisioned read capacity to 2000 RCU would directly address the read throttling, and implementing DAX caching would offload read traffic, reducing the load on the DynamoDB table. Option A is incorrect because decreasing write capacity does not free up read capacity; DynamoDB provisioned capacity for reads and writes is independent. Option B is incorrect because increasing the auto scaling target utilization to 90% would actually cause scaling to trigger at a higher utilization, potentially leading to more throttling, not less. Option C is incorrect because DynamoDB does not use storage types like GP2; that is a concept for Amazon EBS volumes, not applicable to DynamoDB.

Answer

Decrease the provisioned write capacity to 500 WCU to free up resources.

Answer

Increase the auto scaling target utilization to 90% to allow more headroom.

Answer

Change the storage type to General Purpose SSD (gp2) to improve I/O.

Question 3

A company needs to store and analyze JSON documents that contain nested fields. The data is used for real-time dashboards and ad-hoc queries. The team wants a fully managed solution that supports both key-value lookups and SQL-like queries. Which AWS service should they use?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is correct because it is a fully managed NoSQL key-value and document database that supports single-digit millisecond latency for key-value lookups, and its PartiQL-compatible query language enables SQL-like queries on JSON documents with nested fields. DynamoDB also integrates with AWS services like Lambda and Kinesis for real-time dashboards, and its adaptive capacity handles ad-hoc query patterns without manual scaling.

Answer

Amazon Redshift

Answer

Amazon RDS for PostgreSQL with JSONB

Answer

Amazon DocumentDB

Question 4

A company needs to choose a database for a real-time analytics workload that requires sub-second query latency on streaming data. Which TWO AWS services are most suitable?

Accepted Answer

Amazon Redshift with streaming ingestion from Kinesis.. Amazon Timestream is purpose-built for time-series data and provides sub-second query latency on streaming data via its dedicated query engine and automatic tiering between in-memory and magnetic stores. Amazon Redshift with streaming ingestion from Kinesis enables real-time analytics by directly consuming Kinesis data streams into Redshift materialized views, allowing sub-second queries on fresh data without batch loading.

Answer

Amazon Neptune.

Answer

Amazon RDS for PostgreSQL with materialized views.

Answer

Amazon DynamoDB Accelerator (DAX).

Question 5

A startup wants to store session data for a web application. Each session is small (under 1 KB) and accessed frequently with low latency. The data can be ephemeral and does not require complex queries. Which AWS database service is most suitable?

Accepted Answer

Amazon ElastiCache for Redis. Amazon ElastiCache for Redis is the most suitable choice because it is an in-memory data store that provides sub-millisecond latency for frequent reads and writes, ideal for ephemeral session data under 1 KB. Redis supports key-value storage with built-in time-to-live (TTL) expiration, which automatically removes stale sessions without additional application logic, and its simple data model avoids the overhead of complex queries.

Answer

Amazon DynamoDB

Answer

Amazon RDS for PostgreSQL

Answer

Amazon Neptune

Question 6

A company is running an RDS for MySQL database and needs to ensure that all connections to the database use SSL encryption. Which configuration step is required?

Accepted Answer

Set 'require_secure_transport' to ON in the DB parameter group.. Setting 'require_secure_transport' to ON in the DB parameter group forces all connections to the RDS for MySQL database to use SSL/TLS encryption. This parameter is supported in MySQL 5.7 and later, and when enabled, the server rejects non-encrypted connections, ensuring compliance with security policies.

Answer

Enable 'Enable SSL' in the RDS console.

Answer

Set 'rds.force_ssl' to 1 in the DB parameter group.

Answer

Set 'ssl' to 'require' in the DB parameter group.

Question 7

An administrator notices that the CloudWatch metric 'ReadLatency' for an Amazon RDS for SQL Server instance has increased significantly. Which of the following is the most likely cause?

Accepted Answer

The DB instance does not have enough provisioned IOPS.. High ReadLatency indicates that read operations are taking longer than expected. This is most directly caused by insufficient I/O throughput, i.e., not enough provisioned IOPS for the workload. When the database requests more IOPS than are provisioned, I/O operations queue up, increasing latency. Option D is correct because insufficient provisioned IOPS is a primary cause of increased ReadLatency. Option A is incorrect: high CPU utilization can affect overall performance but does not directly cause read latency unless it leads to I/O contention. Option B is incorrect: running out of memory can cause disk swapping, which may increase latency, but it is less direct than I/O throttling. Option C is incorrect: burstable instance classes (like T-series) use CPU credits; exhaustion affects CPU performance, not storage I/O latency.

Answer

The DB instance is experiencing high CPU utilization.

Answer

The DB instance is running out of memory.

Answer

The DB instance is using a burstable instance class that has exhausted its credits.

Question 8

A company is migrating a 500 GB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime and support ongoing changes during migration. Which approach should they take?

Accepted Answer

Use AWS DMS with full load and change data capture (CDC). AWS DMS with full load and change data capture (CDC) is the correct approach because it allows the initial 500 GB data load to be migrated while continuously replicating ongoing changes from the source SQL Server database to Amazon RDS for SQL Server. This minimizes downtime by enabling a cutover only after the target is fully synchronized, and it supports ongoing changes during migration without requiring the source database to be taken offline.

Answer

Use native SQL Server backup and restore to RDS

Answer

Set up a Direct Connect connection and use log shipping

Answer

Use SQL Server Integration Services (SSIS) to replicate data

Question 9

A company is using Amazon RDS for SQL Server with Multi-AZ deployment. The security team requires that all database activity be monitored for suspicious queries. The database specialist enabled RDS Database Activity Streams and configured AWS Lambda to process the stream. However, the Lambda function fails to process some events when the database fails over to the standby instance. What is the most likely cause?

Accepted Answer

The Lambda function does not re-establish the stream session after a failover event.. When a failover occurs, the RDS Database Activity Stream session is tied to the original primary instance. The Lambda function must re-establish the stream session to the new primary instance to continue processing events. If it does not, events during failover are lost. Option A is incorrect because the security group controls network access to the RDS endpoint, which remains the same after failover; connectivity is not the issue. Option C is incorrect because parameter group settings apply to both primary and standby instances; the activity stream setting is not parameter group-dependent. Option D is incorrect because the KMS key used for encryption is available in the same region; region unavailability is not a factor in Multi-AZ deployments within a single region.

Answer

The security group does not allow the Lambda function to connect to the new primary instance.

Answer

The parameter group for the standby instance does not have the activity stream enabled.

Answer

The KMS key used to encrypt the activity stream is not available in the standby instance's Region.

Question 10

A web application uses Amazon DynamoDB as its database. The application frequently queries items using a secondary index. The index's partition key has high cardinality, but the query latency is higher than expected. Which action would MOST likely improve query performance?

Accepted Answer

Increase the read capacity units (RCU) for the global secondary index.. A Global Secondary Index (GSI) has its own provisioned read capacity, separate from the base table. If the GSI's read capacity units (RCU) are insufficient to handle the query workload, requests may be throttled, leading to higher latency. Increasing the RCU for the GSI directly addresses this bottleneck by allowing more concurrent read operations against the index.

Answer

Use a Scan operation instead of Query to retrieve items from the index.

Answer

Add additional sort key attributes to the index to better distribute the data.

Answer

Convert the global secondary index to a local secondary index.

Question 11

A database administrator needs to audit all SQL statements executed on an Amazon Aurora MySQL DB cluster, including SELECT queries. Which AWS service should be used to capture and store these logs?

Accepted Answer

Amazon RDS Database Activity Streams. Amazon RDS Database Activity Streams (Option A) is the correct service to capture and store audit logs of SQL statements, including SELECT queries, on an Aurora MySQL DB cluster. It streams database activity to Amazon CloudWatch Logs and Amazon Kinesis Data Streams for further analysis and storage. Option B (Amazon RDS Enhanced Monitoring) provides OS-level metrics, not SQL statements. Option C (Amazon CloudWatch Logs) can store logs but does not capture SQL statements directly; it requires a source like Database Activity Streams. Option D (Amazon RDS Performance Insights) monitors database performance, not SQL audit logs.

Answer

Amazon RDS Enhanced Monitoring

Answer

Amazon CloudWatch Logs

Answer

Amazon RDS Performance Insights

Question 12

A company is migrating its on-premises MySQL database to Amazon Aurora MySQL. The current database has a table of 500 GB that is accessed by a nightly batch job that updates 80% of the rows. The company wants to minimize downtime during migration. Which migration strategy is MOST appropriate?

Accepted Answer

Use AWS Database Migration Service (DMS) with Aurora as the target.. AWS DMS supports ongoing replication from an on-premises MySQL source to Amazon Aurora MySQL, allowing the nightly batch job to continue running during the initial full load. After the full load completes, DMS captures incremental changes and applies them to Aurora, enabling a cutover with minimal downtime. This approach is ideal for large tables (500 GB) with high update volumes because it avoids a lengthy offline export/import process.

Answer

Create an Aurora read replica from the on-premises database.

Answer

Export the data to Amazon S3 and load it into Aurora using the LOAD DATA FROM S3 command.

Answer

Use mysqldump to export the database and import it into Aurora.

Question 13

A team is troubleshooting an Amazon DynamoDB table that is throttling write requests. The table has on-demand capacity mode enabled. Which of the following is the most likely cause of the throttling?

Accepted Answer

The write traffic exceeds the table's previous peak traffic by more than double.. Even with on-demand capacity, DynamoDB can throttle write requests if the write traffic exceeds the table's previous peak traffic by more than double. On-demand capacity is designed to handle traffic spikes up to double the previous peak within a 30-minute window. If the spike surpasses that threshold, throttling may occur. Option B correctly identifies this cause. Option A is incorrect because on-demand mode does not use provisioned capacity. Option C is incorrect because adaptive capacity is a feature of provisioned mode, not on-demand. Option D, an AWS Health event, could cause issues but is not the most likely given normal operation.

Answer

The table has exceeded its provisioned write capacity units.

Answer

The table is not using adaptive capacity.

Answer

There is an active AWS Health event affecting the DynamoDB service.

Question 14

A company has an Amazon Redshift cluster with a single node. The cluster is used for reporting. Recently, queries have become slow, and the cluster's disk space is 80% full. Which action should be taken to improve query performance and manage storage?

Accepted Answer

Resize the cluster to include additional compute nodes.. Resizing the cluster to add compute nodes distributes data and workload across more nodes, improving query performance and increasing storage capacity. Option B is wrong because enabling compression (ENCODE AUTO) can reduce storage space but does not directly address the performance bottleneck caused by high disk usage on a single node; it also is not a quick fix for existing data. Option C is wrong because changing distribution style to ALL replicates all data to every node, which actually increases storage consumption and may worsen performance on a single-node cluster. Option D is wrong because running VACUUM reclaims space from deleted rows, but the cluster is 80% full and VACUUM does not add new storage capacity; it may provide temporary relief but not a long-term solution for performance.

Answer

Enable compression on all columns using the ENCODE AUTO option.

Answer

Modify the table's distribution style to DISTSTYLE ALL for all tables.

Answer

Run the VACUUM command to reclaim space from deleted rows.

Question 15

A company uses Amazon DynamoDB for a high-traffic gaming leaderboard. The table has a partition key of 'game_id' and a sort key of 'score'. During a tournament, the application experiences throttling on a single partition. The application uses strongly consistent reads. Which TWO actions should be taken to resolve the throttling and maintain performance?

Accepted Answer

Redesign the partition key to include a random suffix to distribute writes across partitions.. The correct actions are A and D. Option A: Redesigning the partition key to include a random suffix (e.g., appending a shard number) distributes write traffic across multiple partitions, preventing a single hot partition from throttling. Option D: For a leaderboard, eventually consistent reads are sufficient for non-critical queries, reducing read capacity consumption and alleviating read-side throttling. Option B (DAX) only caches reads and does not help with write throttling. Option C (increasing RCU) addresses read capacity, not write distribution to fix the hot partition. Option E (GSI) creates a separate index but does not redistribute writes on the base table's primary partition.

Answer

Enable DynamoDB Accelerator (DAX) to cache the most frequently read items.

Answer

Increase the provisioned read capacity units (RCU) for the table.

Answer

Create a global secondary index (GSI) with a different partition key.

Question 16

A company has a compliance requirement to encrypt all RDS snapshots at rest using a customer-managed KMS key. The RDS instance is already encrypted with an AWS-managed key. What is the correct procedure to ensure snapshots use the customer-managed key?

Accepted Answer

Take a snapshot of the RDS instance, copy the snapshot specifying the customer-managed KMS key, and restore from the copied snapshot.. To encrypt RDS snapshots with a customer-managed KMS key, you must first take a snapshot of the existing instance (which uses an AWS-managed key). Then, copy that snapshot and specify the customer-managed KMS key during the copy operation. Finally, restore from the copied snapshot to create a new instance encrypted with the customer-managed key. Option A is incorrect because you cannot change the encryption key of an existing instance; you must copy the snapshot. Option B is correct and describes the proper procedure. Option C is incorrect because the default KMS key for the account does not affect existing instance snapshots. Option D is incorrect because you cannot modify an existing RDS instance to use a different encryption key directly; the encryption key is set at creation.

Answer

Create a new RDS instance with the customer-managed KMS key and migrate data using DMS.

Answer

Change the default KMS key for the AWS account to the customer-managed key.

Answer

Modify the RDS instance to use the customer-managed KMS key directly.

Question 17

A database administrator is responsible for managing an Amazon RDS for Oracle DB instance. The DBA needs to ensure that all changes to the DB instance's security group rules are logged for audit purposes. Which TWO services can be used together to achieve this? (Select TWO.)

Accepted Answer

AWS CloudTrail. AWS CloudTrail logs API calls made to the AWS account, including changes to security group rules (e.g., AuthorizeSecurityGroupIngress). By sending CloudTrail logs to Amazon CloudWatch Logs, you can create metrics filters and alarms to monitor and alert on specific API calls, enabling audit logging of security group rule changes. AWS Config tracks configuration changes but does not provide real-time log streaming to CloudWatch Logs for API calls. VPC Flow Logs capture network traffic, not API calls. Amazon Inspector is a vulnerability assessment service, not for logging API calls.

Answer

Amazon Inspector

Answer

AWS Config

Answer

Amazon VPC Flow Logs

Question 18

A company is designing a database for a global e-commerce application that requires low-latency reads and writes with strong consistency. The application is expected to handle millions of requests per second and requires high availability. Which AWS database service is most suitable for this workload?

Accepted Answer

Amazon DynamoDB with DynamoDB Accelerator (DAX). Amazon DynamoDB with DAX is the most suitable choice because DynamoDB itself provides single-digit millisecond latency at any scale, supports strong consistency for both reads and writes (via ConsistentRead=true for reads), and is designed for high availability and millions of requests per second. DAX is an in-memory cache that accelerates reads, but it only supports eventual consistency; however, reads requiring strong consistency can be served directly from DynamoDB while DAX handles the majority of eventually consistent reads, thereby meeting the low-latency and strong consistency requirements of the application.

Answer

Amazon ElastiCache for Memcached

Answer

Amazon S3 with S3 Select

Answer

Amazon RDS for MySQL with Multi-AZ deployment

Question 19

A company is using Amazon DynamoDB with provisioned capacity. The table's read capacity is consistently underutilized, but the write capacity is frequently maxed out. The team wants to optimize costs while maintaining performance. Which TWO actions should be taken?

Accepted Answer

Use DynamoDB Auto Scaling for write capacity.. The correct answers are C and E. DynamoDB Auto Scaling for write capacity (C) dynamically adjusts the provisioned write capacity based on traffic, preventing throttling during spikes without over-provisioning. Reducing provisioned read capacity (E) to match actual usage saves costs because reads are underutilized. Option A (on-demand) can be more expensive for predictable workloads, and Auto Scaling is often more cost-effective. Option B (DAX) offloads reads, not writes, so it does not address the write bottleneck. Option D (increasing provisioned writes) would raise costs without dynamic scaling, as capacity would remain high even when not needed.

Answer

Switch the table to on-demand capacity mode.

Answer

Enable DynamoDB Accelerator (DAX) to offload reads.

Answer

Increase the provisioned write capacity to handle spikes.

Question 20

A company is designing an Amazon RDS for MySQL database for an e-commerce application. Which TWO design strategies will help ensure high availability and automatic failover in the event of a primary instance failure?

Accepted Answer

Use Amazon Aurora instead of RDS MySQL.. Amazon Aurora is a MySQL-compatible database engine that provides built-in high availability and automatic failover across multiple Availability Zones, with up to 15 low-latency read replicas. Option C is correct because enabling Multi-AZ deployment for Amazon RDS MySQL provisions a synchronous standby replica in a different Availability Zone, and Amazon RDS automatically fails over to the standby in the event of a primary instance failure. Both strategies ensure automatic failover without manual intervention. Options B and D involve read replicas, which are for read scaling and require manual promotion for failover, not automatic. Option E (automatic backups) provides point-in-time recovery, not high availability or failover.

Answer

Create a read replica in the same Availability Zone.

Answer

Provision read replicas in different Availability Zones.

Answer

Enable automatic backups.