DBS-C01 Management and Operations Practice Test 17 — 15 Questions

Question 1

A company is using Amazon DynamoDB with Auto Scaling enabled. During a flash sale, write traffic spikes and the application experiences ProvisionedThroughputExceededException errors. The DynamoDB table has provisioned write capacity of 1000 WCU and Auto Scaling is set to scale between 1000 and 10000 WCU. What is the most likely cause of the throttling?

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

Accepted Answer

Auto Scaling cannot react quickly enough to sudden traffic spikes.. DynamoDB Auto Scaling uses a target tracking policy that adjusts capacity based on consumed WCU over a period (typically 5 minutes). During sudden traffic spikes, the consumption increases rapidly, but Auto Scaling cannot react immediately; there is a lag before the scaling policy triggers and additional capacity is provisioned. This results in ProvisionedThroughputExceededException errors until the new capacity takes effect. Option B is incorrect because throttling is due to insufficient write capacity, not partitioning. Option C is incorrect because burst capacity provides a short-term buffer but is quickly exhausted during sustained spikes. Option D is incorrect because the maximum WCU of 10000 is higher than the spike demand, so the limit is not the issue—the timing of the scaling action is the problem.

Answer

The DynamoDB table has insufficient partitions to handle the traffic.

Answer

The table's burst capacity is exhausted and Auto Scaling has not yet increased capacity.

Answer

The Auto Scaling policy has a maximum WCU limit that is too low.

Question 2

A database administrator is troubleshooting a backup failure for an Amazon RDS for SQL Server DB instance. The error message states 'Insufficient storage capacity for backup. Free storage space is 0 GB.' The DB instance has 200 GB allocated storage. What is the most likely cause?

Accepted Answer

The DB instance has insufficient free storage space to perform the backup.. RDS requires free storage space to perform backups and manage transaction logs. With 0 GB free, the backup fails. Option B is incorrect because the number of manual snapshots does not affect the storage capacity of the DB instance; manual snapshots are stored separately in Amazon S3. Option C is incorrect because although transaction logs consume allocated storage, the error specifically indicates insufficient free storage for the backup operation, and the most likely cause is that the instance lacks free storage. Option D is incorrect because setting the backup retention period to 0 days disables automated backups entirely; it does not cause a backup failure due to insufficient storage.

Answer

The DB instance has reached the maximum number of manual snapshots.

Answer

The transaction logs are consuming all allocated storage.

Answer

The backup retention period is set to 0 days, disabling automated backups.

Question 3

A company has an Amazon Aurora MySQL DB cluster with a single writer and two readers. The writer instance fails, and the failover mechanism promotes one of the readers to writer. The application, which uses a custom connection pool, continues to experience errors for several minutes. What should the database administrator do to minimize downtime during future failovers?

Accepted Answer

Modify the application to use the cluster endpoint instead of the instance endpoint.. The cluster endpoint always points to the current writer, so after a failover it automatically routes to the new writer without application changes. Option A is wrong because increasing the connection pool size does not help the application detect the new writer; it could even cause more failed connections. Option C is wrong because the reader endpoint only routes to read replicas, not the writer, so write traffic would fail. Option D is wrong because Aurora already provides Multi-AZ replication; there is no separate 'enable Multi-AZ' setting.

Answer

Increase the connection pool size to handle more connections.

Answer

Configure the application to use the reader endpoint for all traffic.

Answer

Enable Multi-AZ on the Aurora cluster.

Question 4

A development team is using Amazon DynamoDB with on-demand capacity mode for a new application. During initial testing, they notice that write requests are occasionally throttled during traffic bursts. They have enabled DynamoDB Accelerator (DAX) for read-heavy operations. What is the best recommendation to eliminate write throttling?

Accepted Answer

Review the table's partition key design to avoid hot keys.. Write throttling in DynamoDB on-demand mode indicates a hot partition, often due to uneven partition key distribution. Reviewing and improving partition key design can eliminate hot keys and distribute write traffic evenly, preventing throttling. Option A is incorrect: while adaptive capacity helps, it does not fully resolve throttling from skewed access patterns. Option B is incorrect: provisioned capacity with Auto Scaling adds complexity but does not address hot partitions; on-demand already scales automatically. Option C is incorrect: DAX is a read cache and does not affect write operations; increasing DAX node size only improves read performance.

Answer

Enable DynamoDB adaptive capacity to automatically adjust partition throughput.

Answer

Switch to provisioned capacity mode with Auto Scaling.

Answer

Increase the DAX cluster node size to handle more write traffic.

Question 5

A company's Amazon RDS for Oracle instance is running out of storage space. The database administrator wants to add storage without downtime. Which action should be taken?

Accepted Answer

Use the 'Modify DB Instance' action to increase the allocated storage.. Amazon RDS allows you to modify allocated storage online using the 'Modify DB Instance' action without significant downtime. Option A is wrong because deleting old archived redo logs can free up space temporarily but does not add storage and may impact point-in-time recovery. Option B is wrong because taking a snapshot and restoring to a larger instance requires downtime during the restore process. Option D is wrong because creating a new instance and migrating data involves downtime and is more complex than simply modifying storage.

Answer

Delete old archived redo logs to free up space.

Answer

Take a snapshot and restore to a larger instance.

Answer

Create a new DB instance with larger storage and migrate the data.

Question 6

A database administrator needs to audit all SQL queries executed on an Amazon RDS for PostgreSQL instance, including SELECT statements. Which two most efficient ways to achieve this?

Accepted Answer

Install the pgAudit extension and configure it to log all statements.. The pgAudit extension for PostgreSQL can be installed on RDS and configured to log all SQL statements, including SELECT queries. Option C is also correct because configuring the DB instance to export logs to Amazon CloudWatch Logs, when combined with enabling statement logging via the RDS parameter group (e.g., setting log_statement = 'all'), allows centralized log management and analysis, effectively auditing all queries. Option A is wrong because AWS CloudTrail does not capture SQL query content; it logs API actions on the RDS instance itself. Option D is wrong because Enhanced Monitoring provides OS-level metrics, not SQL query logs. Therefore, both B and C are correct.

Answer

Enable AWS CloudTrail for the RDS instance.

Answer

Enable Enhanced Monitoring for the DB instance.

Question 7

A company is using Amazon DynamoDB with Auto Scaling enabled. During a flash sale, write traffic spikes and the application experiences ProvisionedThroughputExceededException errors. The DynamoDB table has provisioned write capacity of 1000 WCU and Auto Scaling is set to scale between 1000 and 10000 WCU. What is the most likely cause of the throttling?

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

Accepted Answer

Configure a scheduled scaling action in Application Auto Scaling to increase WCU before the campaign.. Using Application Auto Scaling scheduled scaling allows pre-scaling capacity before the predictable spike, preventing throttling. Option A is incorrect because on-demand mode is for unpredictable traffic and may be costlier; for predictable spikes, scheduled scaling is more cost-effective. Option B is wrong because DAX is a caching layer for reads, not writes. Option C is wrong because simply increasing the maximum WCU does not pre-scale capacity; it only raises the upper limit that Auto Scaling can reach after throttling occurs.

Answer

Switch the table to on-demand capacity mode.

Answer

Enable DynamoDB Accelerator (DAX) to cache write requests.

Answer

Increase the maximum provisioned WCU in the Auto Scaling policy.

Question 8

A company is running an Amazon RDS for MySQL instance with Multi-AZ. The primary instance in us-east-1a fails, and the standby in us-east-1b is promoted. The application cannot connect after failover. Which TWO steps should the database administrator take to restore connectivity?

Accepted Answer

Update the application's connection string to point to the new writer endpoint.. After failover, the application may be connecting to the old primary instance endpoint. Updating the connection string to the DNS writer endpoint (which automatically points to the new primary) ensures connectivity. Option D is correct because after failover, the writer endpoint's DNS record updates to the new primary's IP. Waiting for propagation and flushing the DNS cache ensures the application resolves the updated IP. Option B is incorrect because rebooting is not required and would cause further disruption. Option C is incorrect because the security group already permits traffic from the application; the issue is DNS resolution, not network access. Option E is incorrect because creating a read replica does not solve the connectivity issue and is unnecessary for a Multi-AZ failover.

Answer

Reboot the new primary instance to reset connections.

Answer

Update the security group to allow inbound traffic from the application.

Answer

Create a read replica and promote it to a new primary.

Question 9

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a tight migration window of 8 hours. Which THREE steps should be taken to minimize downtime during the migration?

Accepted Answer

Use AWS Database Migration Service (AWS DMS) with ongoing replication.. AWS DMS with ongoing replication (option C) allows continuous data replication from the source to the target, minimizing downtime during the final cutover. Disabling automated backups on the target RDS instance (option D) reduces I/O overhead and speeds up the migration process. Deploying a large RDS instance class (option E) provides higher network and disk throughput, accelerating the initial data load. Option A is incorrect because a manual snapshot is not used for migration, and option B is incorrect because AWS SCT is for schema conversion, not data replication.

Answer

Take a manual snapshot of the source database before migration.

Answer

Use AWS Schema Conversion Tool (AWS SCT) to convert the schema.

Question 10

A company uses Amazon DynamoDB for a gaming application. During a new game launch, the application experiences high latency and throttling on a table with a partition key of 'user_id' and a sort key of 'timestamp'. The access pattern is to query recent items for a given user. Which TWO design changes can improve performance?

Accepted Answer

Use a composite key with 'game_id' as partition key and 'timestamp' as sort key.. Using a composite key with 'game_id' as partition key and 'timestamp' as sort key distributes traffic more evenly if 'game_id' has high cardinality, reducing hot partitions. Option C is correct because adding a Global Secondary Index (GSI) with a different partition key allows queries to be served from the index, offloading read traffic from the base table. Option A is incorrect because strongly consistent reads do not solve hot partition issues and consume more throughput. Option D is incorrect because increasing read capacity does not address the root cause of a hot partition; the table may still throttle requests to the hot partition. Option E is incorrect because DAX is a caching layer for reads, not writes, and does not resolve partition-level throttling.

Answer

Use strongly consistent reads for all queries.

Answer

Increase the provisioned read capacity for the table.

Answer

Enable DynamoDB Accelerator (DAX) to cache write operations.

Question 11

A company is running an Amazon RDS for MySQL DB instance. The database performance has degraded over time, and the company suspects that slow queries are the cause. Which AWS service should the company use to identify the slow queries and analyze the database performance?

Accepted Answer

Amazon RDS Performance Insights. Performance Insights provides a dashboard to analyze database performance and identify slow queries. AWS Trusted Advisor (A) provides best-practice checks, not query analysis. Amazon RDS Enhanced Monitoring (B) provides OS metrics, not query details. Amazon CloudWatch Logs (C) is for logs, not query analysis.

Answer

AWS Trusted Advisor

Answer

Amazon RDS Enhanced Monitoring

Answer

Amazon CloudWatch Logs

Question 12

A company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a 24-hour maintenance window. The company needs to minimize downtime during the migration. Which AWS service should be used to perform the migration with minimal downtime?

Accepted Answer

AWS Database Migration Service. AWS Database Migration Service (AWS DMS) can migrate the on-premises Oracle database to Amazon RDS for Oracle with minimal downtime by using ongoing replication. Option B (Oracle Data Guard) is not supported for cross-environment replication to Amazon RDS. Option C (AWS Schema Conversion Tool) is used for schema conversion, not data migration. Option D (AWS Data Pipeline) is a data orchestration service unrelated to database migration.

Answer

Oracle Data Guard

Answer

AWS Schema Conversion Tool (AWS SCT)

Answer

AWS Data Pipeline

Question 13

A company has a production Amazon RDS for PostgreSQL Multi-AZ DB instance. The company's security team requires that all database connections use IAM database authentication. The company also needs to ensure that connections from a specific application server are allowed only if the server has a valid IAM role. Which combination of steps should the database administrator take to meet these requirements?

Accepted Answer

Enable IAM database authentication on the RDS instance. Create a database user that matches the IAM role ARN. Grant the application server's IAM role the rds_iam role. Configure the application to generate an authentication token using the IAM role's credentials.. IAM database authentication for RDS PostgreSQL requires mapping IAM roles to database users. Steps: 1) Enable IAM database authentication on the RDS instance. 2) Create a database user that matches the IAM role ARN (the role assumed by the application server). 3) Grant the rds_iam role to the application server's IAM role to allow it to authenticate. 4) Configure the application to generate an authentication token using the IAM role's credentials. Option D is correct because it includes all these steps. Option A is wrong because it uses a password instead of an authentication token. Option B is wrong because it references an IAM user ARN instead of a role ARN. Option C is wrong because it does not enable IAM authentication and uses a password.

Answer

Create a database user with a strong password. Enable IAM database authentication. Assign the application server an IAM policy that allows rds-db:connect. Configure the application to use the password.

Answer

Enable IAM database authentication. Create a database user matching the IAM user ARN. Grant the application server's IAM user the rds_iam role. Configure the application to use an authentication token.

Answer

Enable IAM database authentication. Create a database user that matches the IAM role ARN. Configure the application to use the database master username and password.

Question 14

A company is using Amazon DynamoDB for a web application. The company notices that read requests to a particular table are throttled during peak hours. The table has a provisioned read capacity of 1000 read capacity units (RCUs). The read requests are mostly eventually consistent reads. What should the company do to reduce throttling without changing the application code?

Accepted Answer

Increase the provisioned read capacity for the table.. Increasing provisioned read capacity directly provides more RCUs, reducing throttling without code changes. Option A is wrong because ElastiCache would require application code changes to implement caching. Option B is wrong: Switching to strongly consistent reads would double RCU consumption per read (for reads up to 4 KB) or increase it, worsening throttling. Option C is wrong: DAX does require code changes to integrate (though minimal), and the question specifically asks for no application code changes.

Answer

Use Amazon ElastiCache to cache the read results.

Answer

Switch to strongly consistent reads to reduce the number of read requests.

Answer

Implement DynamoDB Accelerator (DAX) to cache read requests.

Question 15

A company is running an Amazon RDS for SQL Server DB instance. The company needs to capture changes to a specific table and replicate them to an Amazon S3 bucket in near real time. Which AWS service should be used to achieve this?

Accepted Answer

AWS Database Migration Service (AWS DMS) with ongoing replication. AWS DMS with ongoing replication (change data capture) is the correct choice because it can continuously capture changes from the RDS for SQL Server source and replicate them to an Amazon S3 bucket in near real time. Option A (AWS Glue) is incorrect because AWS Glue is a batch ETL service, not designed for real-time change data capture. Option C (Amazon RDS for SQL Server native replication) is incorrect because native replication features like Always On Availability Groups or log shipping replicate data to another SQL Server instance, not directly to S3. Option D (Amazon Kinesis Data Streams) is incorrect because while it can ingest streaming data, it would require additional custom application logic to capture changes from RDS and push to Kinesis, making it less straightforward than DMS for this use case.

Answer

AWS Glue

Answer

Amazon RDS for SQL Server native replication

Answer

Amazon Kinesis Data Streams