DBS-C01 Management and Operations Practice Test 5 — 15 Questions

Question 1

A database administrator runs the above AWS CLI command. What is the purpose of the command?

Accepted Answer

Retrieve average number of database connections for mydb.. The AWS CLI command `aws cloudwatch get-metric-statistics` with the namespace `AWS/RDS`, metric name `DatabaseConnections`, and statistic `Average` retrieves the average number of database connections for the specified DB instance `mydb` over the given time period. The `--metric-name DatabaseConnections` parameter explicitly targets the connection count metric, making option B correct.

Answer

Retrieve average free storage space for mydb.

Answer

Retrieve average CPU utilization for mydb.

Answer

Retrieve average write latency for mydb.

Question 2

A company is using Amazon RDS for MySQL with Multi-AZ deployment. The database experiences a failover event, and after failover, the application reports increased latency. Which action should the database specialist take to diagnose the issue?

Accepted Answer

Check Amazon CloudWatch metrics for Database Connections and Latency, and verify DNS resolution.. After a Multi-AZ failover, the DNS record for the RDS endpoint is updated to point to the new primary in a different Availability Zone. If the application's DNS cache still resolves to the old IP (which is now unreachable or in a different AZ), connections may time out or route suboptimally, increasing latency. Checking CloudWatch metrics for Database Connections and Latency helps isolate whether the issue is due to connection churn, resource contention, or DNS caching, while verifying DNS resolution confirms the application is connecting to the correct endpoint.

Answer

Promote the secondary instance to primary manually.

Answer

Create a new read replica and redirect traffic.

Answer

Force a reboot of the DB instance to reset connections.

Question 3

A company has an Amazon DynamoDB table with on-demand capacity mode. They notice that write requests are being throttled during peak hours. The table has a global secondary index (GSI) that is also throttled. Which action should the database specialist take to resolve the throttling?

Accepted Answer

Review the partition key design and consider adding a suffix to distribute writes more evenly.. The throttling of both the base table and the GSI during peak hours indicates a hot partition caused by an uneven distribution of write activity. Reviewing the partition key design and adding a suffix to distribute writes more evenly is the correct action because it addresses the root cause: DynamoDB's on-demand mode automatically scales capacity, but it cannot overcome a skewed access pattern that overloads a single partition. By spreading writes across more partitions, you eliminate the hot spot and prevent throttling without changing capacity mode.

Answer

Enable DynamoDB Streams to offload write operations.

Answer

Switch to provisioned capacity mode and increase write capacity units (WCU).

Answer

Increase the write capacity of the GSI by updating the table's provisioned throughput.

Question 4

A database specialist needs to capture SQL queries executed against an Amazon Aurora MySQL DB cluster for performance analysis. The capture should have minimal performance impact and be stored in Amazon CloudWatch Logs. Which feature should the specialist use?

Accepted Answer

Enable Performance Insights and configure the Performance Insights log export to CloudWatch Logs.. Performance Insights captures SQL queries with minimal overhead by sampling the database engine's internal wait states and query activity, then exports this data to CloudWatch Logs for analysis. This approach is designed for performance monitoring without the significant performance impact of enabling full logging (like the general log), making it ideal for capturing queries for performance analysis.

Answer

Enable the slow query log and export to CloudWatch Logs.

Answer

Enable database audit logs and export to CloudWatch Logs.

Answer

Enable the general log and publish to CloudWatch Logs.

Question 5

A company runs a production Amazon RDS for PostgreSQL database. The database specialist needs to perform a major version upgrade with minimal downtime. Which strategy should the specialist use?

Accepted Answer

Create a read replica with the new major version, promote it to primary, and update the application connection string.. Creating a read replica with the new major version, promoting it to primary, and updating the application connection string minimizes downtime by allowing the replica to catch up with the source database before promotion. This approach avoids the prolonged unavailability associated with in-place upgrades, as the promotion process typically takes only a few seconds, and the application can be switched over with a simple connection string update.

Answer

Take a snapshot of the database, launch a new instance from the snapshot, and upgrade it.

Answer

Modify the DB instance to the new version directly using the AWS Management Console.

Answer

Schedule a maintenance window during off-peak hours and apply the upgrade.

Question 6

A database specialist is troubleshooting a performance issue on an Amazon RDS for MySQL DB instance. The CPU utilization is consistently above 90%, but the IOPS and memory metrics are well within limits. Which tool should the specialist use to identify the root cause?

Accepted Answer

Use Amazon RDS Performance Insights to identify the top SQL queries by CPU usage.. Amazon RDS Performance Insights provides a database performance tuning and monitoring feature that visualizes database load and helps identify the top SQL queries consuming the most CPU. Since the CPU is consistently above 90% while IOPS and memory are normal, Performance Insights can directly correlate high CPU usage to specific SQL statements, enabling the specialist to pinpoint the root cause efficiently.

Answer

Enable AWS CloudTrail to log database queries.

Answer

Use Amazon RDS Enhanced Monitoring to view OS-level metrics.

Answer

Check RDS events in the AWS Management Console.

Question 7

A company has an Amazon DynamoDB table with provisioned capacity. The table experiences occasional spikes in write traffic that exceed the provisioned write capacity units (WCU). Which feature should the database specialist enable to handle these spikes without throttling?

Accepted Answer

Configure DynamoDB Auto Scaling for write capacity.. DynamoDB Auto Scaling automatically adjusts the provisioned read and write capacity based on actual traffic patterns, enabling the table to handle spikes without throttling while maintaining cost efficiency. Option A is incorrect because burst capacity provides a limited buffer for short-term spikes but can be exhausted, leading to throttling. Option C is incorrect because DAX is an in-memory cache for read operations, not writes. Option D is incorrect because switching to on-demand capacity mode can handle spikes but may result in higher costs compared to Auto Scaling with provisioned capacity.

Answer

Enable DynamoDB burst capacity.

Answer

Use DynamoDB Accelerator (DAX) to cache writes.

Answer

Switch to on-demand capacity mode.

Question 8

A database specialist is managing an Amazon RDS for Oracle DB instance. The instance has a large amount of data and the specialist needs to migrate it to a new instance in a different AWS Region. Which method would minimize downtime and be the most efficient?

Accepted Answer

Use AWS Database Migration Service (DMS) with ongoing replication to migrate to the target instance.. AWS DMS with ongoing replication (change data capture) allows you to perform a full load of the existing Oracle database to the target instance in the new region, and then continuously replicate changes from the source until you cut over. This minimizes downtime because you can keep the source database fully operational during the migration and only stop it for a brief period during the final switchover. It is the most efficient method for cross-region migrations because it handles schema conversion, data validation, and ongoing synchronization automatically.

Answer

Export the database to Amazon S3 using Oracle Data Pump, then import into the new instance.

Answer

Create a cross-region read replica and promote it.

Answer

Take a full backup using Oracle RMAN, copy the backup files to the target region, and restore.

Question 9

A company is using Amazon ElastiCache for Redis as a caching layer in front of an Amazon Aurora MySQL database. The application is experiencing higher latency than expected. Which database design pattern should the specialist recommend to improve read performance?

Accepted Answer

Use Aurora Replicas to offload read traffic from the primary instance.. The application is experiencing higher latency than expected despite using ElastiCache for Redis. This indicates that the cache is not effectively absorbing read traffic, likely due to cache misses or insufficient cache hit ratio. By using Aurora Replicas, read traffic can be offloaded from the primary Aurora instance, reducing load and improving read performance directly at the database layer, which complements the caching layer.

Answer

Increase the ElastiCache cluster size to accommodate more data.

Answer

Enable Multi-AZ on the ElastiCache cluster and use read replicas.

Answer

Implement Amazon DynamoDB Accelerator (DAX) in front of Aurora.

Question 10

A database specialist needs to monitor the resource utilization of Amazon RDS DB instances. Which AWS service provides OS-level metrics such as memory, disk, and CPU usage?

Accepted Answer

Amazon RDS Enhanced Monitoring. Amazon RDS Enhanced Monitoring provides OS-level metrics (e.g., memory, disk, CPU usage) by running an agent on the RDS host and delivering logs to CloudWatch Logs. This is the only service that exposes hypervisor-level and guest OS metrics for RDS instances, enabling granular troubleshooting of resource contention.

Answer

Amazon RDS Performance Insights

Answer

Amazon CloudWatch

Answer

AWS CloudTrail

Question 11

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. Which TWO methods can the database specialist use to minimize downtime during the migration?

Accepted Answer

Use Oracle GoldenGate to replicate data continuously.. Oracle GoldenGate enables continuous, real-time data replication from the source Oracle database to Amazon RDS for Oracle, allowing the source to remain fully operational during the migration. When the cutover is performed, only a brief pause is needed to apply any final transactions, minimizing downtime to seconds or minutes.

Answer

Use Oracle Recovery Manager (RMAN) to back up and restore.

Answer

Take a full database backup and restore to RDS.

Answer

Use Oracle Data Pump to export and import the database.

Question 12

A database specialist is troubleshooting a performance issue on an Amazon Aurora MySQL DB cluster. The cluster has a primary instance and two Aurora Replicas. The application is experiencing high read latency. Which THREE actions should the specialist take to identify the cause?

Accepted Answer

Check the Performance Insights for the Aurora Replicas to identify long-running queries.. Performance Insights provides a detailed view of database load, including wait events, SQL queries, and host-level metrics, which can pinpoint long-running queries causing high read latency on the Aurora Replicas. By analyzing the top SQL statements and their execution plans, the specialist can identify inefficient queries or contention issues that degrade read performance.

Answer

Check the Write Latency metric on the primary instance.

Answer

Increase the instance size of the Aurora Replicas.

Question 13

A company is using Amazon DynamoDB with Auto Scaling enabled. The database specialist notices that write traffic is being throttled occasionally. Which TWO factors could cause throttling despite Auto Scaling?

Accepted Answer

The write traffic exceeds the maximum provisioned capacity that was set for Auto Scaling.. Auto Scaling in DynamoDB operates within a maximum provisioned capacity ceiling. If write traffic exceeds this configured maximum, Auto Scaling cannot increase capacity further, leading to throttling. The service will return ProvisionedThroughputExceededException for requests that exceed the set maximum.

Answer

The table has Global Tables enabled, causing cross-region replication overhead.

Answer

Auto Scaling is not configured to scale up quickly enough for sudden traffic spikes.

Answer

DynamoDB Accelerator (DAX) is not caching write operations.

Question 14

A database specialist created the above IAM policy for a user. When the user attempts to delete an item from the Orders table, what happens?

Accepted Answer

The user cannot delete items because the Deny statement takes precedence.. In IAM, an explicit Deny overrides any Allow. Even though there is an Allow statement that grants DeleteItem permission, the explicit Deny for DeleteItem takes precedence, so the user cannot delete items. Option B is incorrect because the presence of a condition is irrelevant; the Deny is unconditional. Option C is incorrect because the Allow is overridden by the Deny. Option D is incorrect because the Deny in this policy explicitly blocks deletion regardless of other policies.

Answer

The user cannot delete items because the policy does not include a condition.

Answer

The user can delete items because the Allow statement grants permission.

Answer

The user can delete items only if they have another policy that allows it.

Question 15

A database specialist sees the above error in the application logs for an Amazon RDS for MySQL DB instance. The application is a web server running on an EC2 instance. What is the most likely cause?

Accepted Answer

The database connection timed out due to inactivity or network connectivity issues.. The error message in the application logs indicates a connection timeout, which occurs when the client (EC2 web server) cannot establish or maintain a TCP connection to the RDS MySQL DB instance within the configured timeout period. This is most commonly caused by network connectivity issues (e.g., security group rules, NACLs, route tables, or VPC misconfigurations) or prolonged inactivity that triggers the MySQL `wait_timeout` or `interactive_timeout` setting, causing the server to close the connection. Option C directly addresses this scenario, while the other options produce different error codes or symptoms.

Answer

The database user password has expired.

Answer

A user attempted to execute an invalid SQL query.

Answer

The database instance has run out of disk space.