DBS-C01 Management and Operations Practice Test 19 — 15 Questions

Question 1

A database specialist observes the CloudWatch metric for a production RDS for MySQL instance. The max_connections parameter is set to 150. The Sum of DatabaseConnections over 1-minute periods is shown. The application reports intermittent connection failures. What is the most likely cause?

Accepted Answer

The number of connections exceeded the max_connections limit.. Option A is correct because the Sum metric over 1-minute period represents the total number of connections during that minute. A Sum of 200 indicates that at some point during the minute, connections exceeded the max_connections of 150, causing failures. Option B is wrong because the metric shows Sum, not average. Option C is wrong because connection pooling reduces connections, not increases. Option D is wrong because the metric clearly shows high connection counts.

Answer

The average number of connections is below the limit.

Answer

The DatabaseConnections metric is unreliable.

Answer

The application is not using connection pooling.

Question 2

A company is using Amazon RDS for SQL Server with Always On Availability Groups. The primary DB instance is in us-east-1, and the secondary is in us-west-2. The application writes to the primary and reads from the secondary. The secondary instance becomes unreachable due to a network issue. What happens to the primary instance?

Accepted Answer

The primary continues to accept read and write operations.. Option A is correct because the primary continues to accept writes independently; the secondary failure does not affect primary operations. Option B is wrong because failover is not automatic for read replicas. Option C is wrong because the primary does not become read-only. Option D is wrong because write operations continue.

Answer

The primary stops accepting write operations.

Answer

The primary automatically fails over to the secondary.

Answer

The primary becomes read-only until the secondary is restored.

Question 3

A company is migrating a 5 TB MySQL database to Amazon Aurora MySQL. The migration must have minimal downtime and support ongoing replication. The source database is in a corporate data center with a 500 Mbps internet connection. Which THREE steps should the database specialist take?

Accepted Answer

Use AWS Schema Conversion Tool (AWS SCT) to convert the schema.. Options A, C, and E are correct. Option A: AWS DMS with CDC allows ongoing replication with minimal downtime. Option C: Using AWS SCT helps convert the schema if needed. Option E: Using an AWS Snowball Edge device for initial load reduces the time for large data transfer over slow internet. Option B is wrong because a VPN alone does not migrate data. Option D is wrong because a read replica is not a migration tool; it is a feature of Aurora.

Answer

Establish a VPN connection to AWS and use mysqldump.

Answer

Create an Aurora read replica from the source database.

Question 4

A company is using Amazon DynamoDB with auto scaling enabled. The table's write capacity is set to a minimum of 50 and maximum of 500 write capacity units (WCUs). The actual consumed write capacity is consistently at 100 WCUs. What should the database specialist do to optimize costs without impacting performance?

Accepted Answer

Lower the minimum write capacity to 100 WCUs.. Option A is correct because lowering the minimum to 100 WCUs matches the actual usage, preventing over-provisioning. Option B is wrong because decreasing the maximum could cause throttling during spikes. Option C is wrong because increasing the minimum would increase costs. Option D is wrong because disabling auto scaling would require manual management.

Answer

Increase the minimum write capacity to 200 WCUs.

Answer

Disable auto scaling and set the write capacity to 100 WCUs.

Answer

Decrease the maximum write capacity to 200 WCUs.

Question 5

An IAM user has the policy shown. The user is trying to restore a DB instance from a manual snapshot using the AWS CLI. The restore fails with an access denied error. What is the most likely reason?

Accepted Answer

The policy does not grant the rds:RestoreDBInstanceFromDBSnapshot action on the DB instance resource.. Option D is correct because the restore action (RestoreDBInstanceFromDBSnapshot) requires permissions on both the snapshot and the DB instance resource. The policy allows the action on snapshot resources but not on the DB instance resource for the restore action itself. Option A is wrong because the snapshot resource ARN includes '*', which covers all snapshots. Option B is wrong because the action is allowed. Option C is wrong because the snapshot exists.

Answer

The rds:RestoreDBInstanceFromDBSnapshot action is misspelled.

Answer

The snapshot is encrypted and the user does not have permission to use the KMS key.

Answer

The snapshot resource ARN does not include the specific snapshot ID.

Question 6

A company is using Amazon DynamoDB with auto scaling enabled. The table's read capacity is set to a minimum of 100 and maximum of 1000 read capacity units (RCUs). The actual consumed read capacity is consistently at 200 RCUs. What should the database specialist do to optimize costs without impacting performance?

Accepted Answer

Lower the minimum read capacity to 200 RCUs.. Option A is correct because lowering the minimum to 200 RCUs ensures auto scaling does not scale below the actual usage, reducing provisioned capacity costs. Option B is wrong because decreasing the maximum could cause throttling during spikes. Option C is wrong because increasing the minimum would increase costs unnecessarily. Option D is wrong because disabling auto scaling would require manual management and may lead to over-provisioning.

Answer

Decrease the maximum read capacity to 500 RCUs.

Answer

Disable auto scaling and set the read capacity to 200 RCUs.

Answer

Increase the minimum read capacity to 500 RCUs.

Question 7

A company's RDS for MySQL instance is experiencing high CPU utilization. Which AWS service should be used to set up automated actions to scale the instance vertically?

Accepted Answer

AWS Auto Scaling with a target tracking scaling policy. AWS Auto Scaling with a target tracking scaling policy is the correct choice because it can automatically adjust the DB instance class (vertical scaling) for RDS instances based on a defined metric like CPU utilization. This service integrates directly with RDS to modify the instance size without manual intervention, making it ideal for handling high CPU utilization through automated vertical scaling.

Answer

AWS Systems Manager Automation with a custom runbook

Answer

AWS Lambda function to modify the DB instance class

Answer

Amazon CloudWatch Alarms to send an SNS notification to the DBA

Question 8

A database engineer is troubleshooting an Amazon Aurora MySQL DB cluster that is experiencing frequent failovers. The failovers are occurring during periods of low write activity. The engineer notices that the primary instance's writer endpoint is being used for read traffic from a legacy application. What is the most likely cause of the failovers?

Accepted Answer

The primary instance is overloaded due to read traffic from the writer endpoint. Option D is correct because using the writer endpoint for read traffic can overload the primary instance and cause failovers. Option A is wrong because the issue is not about replica lag. Option B is wrong because there is no mention of storage issues. Option C is wrong because failovers do not cause write blocking; they are the result.

Answer

A high replication lag between the primary and replica instances

Answer

A long-running write transaction is blocking the failover

Answer

Insufficient storage for the Aurora cluster volume

Question 9

A company runs a production Amazon RDS for PostgreSQL instance with Multi-AZ deployment. The DB instance has a large number of connections from application servers. The operations team wants to monitor the number of database connections and receive an alert when it exceeds 80% of the maximum connections. Which combination of steps should be taken to set up this monitoring? (Choose two.)

Accepted Answer

Set the alarm threshold to (0.8 * max_connections) and the evaluation period to 1 minute. Correct answers are B and D. B: Create a CloudWatch alarm using the 'DatabaseConnections' metric. D: Set the alarm threshold to 80% of max_connections and the period to 1 minute for timely alerts. A is wrong because RDS Performance Insights does not provide connection count metrics via CloudWatch. C is wrong because Enhanced Monitoring provides OS metrics, not DB connection counts. E is wrong because the max_connections parameter should be checked from the DB parameter group, not the alarm.

Answer

Set the alarm threshold to 80 and the evaluation period to 5 minutes

Answer

Enable Enhanced Monitoring and create a CloudWatch alarm on the 'database_connections' metric

Answer

Enable Performance Insights and create a CloudWatch alarm using the 'DBLoad' metric

Question 10

A company uses Amazon DynamoDB for a gaming application. During a new game launch, the table experiences throttling on write requests. The table has a provisioned capacity of 10,000 WCU and 5,000 RCU. The write traffic pattern shows spikes up to 15,000 WCU for 5 minutes. Which action would resolve the throttling with minimal cost impact?

Accepted Answer

Enable Auto Scaling for DynamoDB with a target utilization of 70%. Option D is correct because DynamoDB Auto Scaling can handle the spikes by scaling up and down, reducing costs. Option A is wrong because doubling WCU would be costly and unnecessary. Option B is wrong because DynamoDB Accelerator (DAX) is for read performance, not writes. Option C is wrong because SQS would add latency and complexity.

Answer

Use Amazon SQS to buffer the write requests

Answer

Increase the provisioned WCU to 20,000 permanently

Answer

Enable DynamoDB Accelerator (DAX) for the table

Question 11

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 500 GB in size and has a 24/7 uptime requirement. The migration window is limited to 2 hours. Which strategy should be used to minimize downtime?

Accepted Answer

Use AWS Database Migration Service (DMS) with ongoing replication. Option C is correct because AWS DMS can replicate ongoing changes and allow a short cutover window. Option A is wrong because AWS SCT does not handle data migration. Option B is wrong because restoring a snapshot takes longer than 2 hours for 500 GB. Option D is wrong because Export/Import requires downtime and is slow.

Answer

Use AWS Schema Conversion Tool (SCT) to convert the schema and copy data

Answer

Take an on-premises backup and restore to RDS using Oracle RMAN

Answer

Export the database to a dump file and import into RDS

Question 12

A database administrator needs to track changes to an Amazon RDS DB instance's configuration, such as modifications to the DB instance class or security group. Which AWS service should be used?

Accepted Answer

AWS Config. Option B is correct because AWS Config records configuration changes to RDS instances. Option A is wrong because CloudTrail records API calls, not configuration state. Option C is wrong because CloudWatch Logs are for log data, not config changes. Option D is wrong because Systems Manager Patch Manager is for patching.

Answer

Amazon CloudWatch Logs

Answer

AWS CloudTrail

Answer

AWS Systems Manager Patch Manager

Question 13

A company is using Amazon DynamoDB with on-demand capacity. The operations team notices that the number of throttled write requests has increased. Which metric should be monitored to determine if the table's write capacity is being exceeded?

Accepted Answer

WriteThrottleEvents. Option D is correct because 'WriteThrottleEvents' directly indicates throttled writes. Option A is wrong because 'ConsumedWriteCapacityUnits' shows actual usage, not throttling. Option B is wrong because 'ProvisionedWriteCapacityUnits' is not applicable for on-demand. Option C is wrong because 'ThrottledWriteRequests' is not a standard CloudWatch metric name (the correct name is WriteThrottleEvents).

Answer

ThrottledWriteRequests

Answer

ProvisionedWriteCapacityUnits

Answer

ConsumedWriteCapacityUnits

Question 14

A company runs an Amazon Aurora MySQL database. The database experiences a sudden spike in connections and then becomes unresponsive. The DB instance has a db.r5.large class with 8 GB memory. The maximum connections parameter is set to the default. Which is the most likely cause of the unresponsiveness?

Accepted Answer

The number of connections exceeded the max_connections limit. Option C is correct because the default max_connections for Aurora MySQL is based on memory, and with 8 GB, it is about 800. A spike exceeding that can exhaust resources. Option A is wrong because storage auto-scaling is seamless. Option B is wrong because burst balance applies to gp2 volumes, but Aurora uses cluster storage. Option D is wrong because replica lag would affect reads, not make the instance unresponsive.

Answer

The DB instance's EBS burst balance dropped to zero

Answer

The storage volume ran out of allocated space

Answer

A read replica had high replication lag

Question 15

A company is running an Amazon RDS for SQL Server instance and wants to automate the patching of the database engine. Which AWS service should be used?

Accepted Answer

AWS Systems Manager Patch Manager. Option C is correct because AWS Systems Manager Patch Manager can automate patching of RDS instances. Option A is wrong because RDS Automated Backups are for backups, not patching. Option B is wrong because RDS Maintenance Windows handle minor engine versions but not OS patching. Option D is wrong because AWS Config is for configuration compliance.

Answer

AWS Config

Answer

Amazon RDS Automated Backups

Answer

Amazon RDS Maintenance Window