DBS-C01 Monitoring and Troubleshooting Practice Test 5 — 15 Questions

Question 1

A database specialist is troubleshooting an Amazon RDS for MySQL DB instance that is running out of storage. The instance has automated backups enabled. The specialist needs to free up storage space immediately without losing backup capability. Which action should the specialist take?

Accepted Answer

Delete older automated backups that are no longer needed.. Option C is correct because deleting old automated backups frees up storage space without affecting the current backup capability. Option A is wrong because modifying the backup retention period does not free space immediately. Option B is wrong because manual snapshots are stored in Amazon S3 and do not affect the DB instance storage. Option D is wrong because disabling backups would stop future backups.

Answer

Modify the DB instance to reduce the backup retention period to 0 days.

Answer

Delete manual snapshots from the RDS console.

Answer

Disable automated backups to stop storage consumption.

Question 2

A company is running a production Amazon RDS for Oracle DB instance. The database specialist is setting up monitoring to detect and troubleshoot performance issues. Which TWO metrics should be used to identify whether the database is experiencing I/O bottlenecks?

Accepted Answer

ReadLatency. ReadLatency and WriteLatency directly measure the time taken for I/O operations. High values indicate I/O bottlenecks. DatabaseConnections and CPUUtilization measure other resources. FreeStorageSpace indicates storage capacity, not performance.

Answer

DatabaseConnections

Answer

CPUUtilization

Answer

FreeStorageSpace

Question 3

A database specialist is troubleshooting a slow-running query on an Amazon Aurora MySQL DB cluster. The query performs a large table scan. Which THREE actions would likely improve query performance?

Accepted Answer

Increase the size of the DB instance to provide more memory and CPU.. Creating appropriate indexes can speed up queries by avoiding table scans. Increasing the instance size provides more memory and CPU for query execution. Enabling query caching can store results of repeated queries. Changing isolation level and enabling parallel query may not help in all cases and may have side effects.

Answer

Change the transaction isolation level to SERIALIZABLE.

Answer

Enable Aurora Parallel Query to parallelize the table scan.

Question 4

A company is using Amazon DynamoDB for a session management application. The application is experiencing higher latency during peak hours. The DynamoDB table uses on-demand capacity. Which TWO steps should a database specialist take to diagnose the issue?

Accepted Answer

Check the CloudWatch metric for ThrottledRequests to see if any requests are being throttled.. Checking ThrottledRequests helps identify if requests are being throttled, even with on-demand. Reviewing PartitionKey metrics helps detect hot partitions. ReadCapacityUnits and WriteCapacityUnits are not applicable for on-demand. Latency metrics show end-to-end performance but are less diagnostic.

Answer

Review the table's ReadCapacityUnits and WriteCapacityUnits to ensure they are sufficient.

Answer

Examine the CloudWatch metric for UserErrors to identify client-side issues.

Answer

Enable DynamoDB Streams to capture all write events for analysis.

Question 5

Refer to the exhibit. A database specialist is investigating performance degradation on an Amazon RDS for MySQL DB instance. The BurstBalance metric shows the values above. What does this indicate, and what action should be taken?

Accepted Answer

The instance has exhausted its I/O burst credits; scale up the allocated storage to increase baseline I/O.. Option B is correct because BurstBalance dropping to 0 indicates that the instance has exhausted its I/O burst credits, causing I/O throttling. Scaling up storage to a larger size increases the baseline I/O performance and burst credit earning rate. Option A is wrong because read replicas do not increase I/O credits. Option C is wrong because enabling Performance Insights only helps diagnose, not resolve. Option D is wrong because changing the instance class does not affect I/O credits.

Answer

The instance is experiencing high read load; add a read replica to offload reads.

Answer

The instance's compute capacity is insufficient; change the instance class to a larger size.

Answer

The instance is experiencing a memory bottleneck; enable Performance Insights to analyze query performance.

Question 6

Refer to the exhibit. A database specialist is troubleshooting an automation script that fails when trying to create a snapshot of the RDS DB instance 'mydb' using an IAM role with the attached policy. The error message indicates that the user is not authorized to perform the operation. Which statement best explains the failure?

Accepted Answer

The policy does not grant the rds:CreateDBSnapshot permission on the DB instance resource.. Option C is correct because the CreateDBSnapshot action requires permissions on both the DB instance and the snapshot resource. The policy only grants access to the snapshot resource, not the DB instance. Options A and B are wrong because the actions are allowed. Option D is wrong because the resource is specified correctly.

Answer

The resource ARN for the snapshot is incorrect; it should specify the DB instance ID.

Answer

The policy does not allow the rds:DescribeDBInstances action on the snapshot resource.

Answer

The policy does not allow the rds:CreateDBSnapshot action on the specific snapshot name.

Question 7

Refer to the exhibit. A database specialist is investigating an application outage that occurred at 14:25 UTC. The RDS event log shows the events above. What is the most likely cause of the outage?

Accepted Answer

A Multi-AZ failover occurred at 14:25 UTC, causing a brief outage.. Option A is correct because a Multi-AZ failover can cause a brief outage during the transition. The restart at 14:30 is likely the result of the failover. Option B is wrong because the restart occurred after the failover. Option C is wrong because the events do not indicate a maintenance window. Option D is wrong because there is no evidence of insufficient storage.

Answer

A maintenance window update was applied, causing the instance to become unavailable.

Answer

The DB instance ran out of storage and became read-only.

Answer

The DB instance restarted at 14:30 UTC due to a manual reboot.

Question 8

A company is running an Amazon RDS for MySQL database. The application team reports that the database is slow. Upon investigation, you notice that the DB instance's CPU utilization is consistently above 90%. Which initial troubleshooting step should you take?

Accepted Answer

Enable Enhanced Monitoring to identify the source of high CPU usage.. Option B is correct because enabling Enhanced Monitoring provides OS-level metrics that can help identify resource bottlenecks. Option A is wrong because increasing instance size without diagnosis may not address the root cause. Option C is wrong because switching storage type does not reduce CPU load. Option D is wrong because deleting slow query logs removes diagnostic data.

Answer

Increase the DB instance size to improve performance.

Answer

Delete the slow query logs to reduce I/O.

Answer

Change the storage type from General Purpose (gp2) to Provisioned IOPS (io1).

Question 9

A developer is troubleshooting an application that uses Amazon DynamoDB. The application is experiencing throttled requests (ProvisionedThroughputExceededException). Which CloudWatch metric should be monitored to troubleshoot this issue?

Accepted Answer

ConsumedWriteCapacityUnits. Option C is correct because ConsumedWriteCapacityUnits shows actual usage; comparing with ProvisionedWriteCapacityUnits helps identify throttling. Option A is wrong because UserErrors is for client-side errors. Option B is wrong because ThrottledRequests is a metric but not a CloudWatch metric name; the actual metric is ConsumedWriteCapacityUnits. Option D is wrong because SuccessfulRequestLatency is about latency, not throttling.

Answer

ThrottledRequests

Answer

SuccessfulRequestLatency

Answer

UserErrors

Question 10

A company's Amazon RDS for PostgreSQL instance is experiencing a high number of connections, causing performance degradation. The DBA wants to identify which user and application are creating the most connections. What should the DBA do?

Accepted Answer

Enable Performance Insights and use the 'db.sql_tokenized' dimension to analyze connections by user.. Option D is correct because Performance Insights with the db.sql_tokenized dimension allows grouping by user and application. Option A is wrong because RDS Enhanced Monitoring does not show SQL-level details. Option B is wrong because VPC Flow Logs capture network traffic, not database connections. Option C is wrong because CloudTrail logs API calls, not database connections.

Answer

Enable AWS CloudTrail to log database logins.

Answer

Enable Enhanced Monitoring and check the 'Connection Count' metric.

Answer

Enable VPC Flow Logs to track connection attempts.

Question 11

A company is using Amazon Redshift for data warehousing. Users report that queries are taking longer than expected. Which CloudWatch metric should be monitored to identify if queries are waiting for resources due to concurrency scaling?

Accepted Answer

ConcurrencyScalingActiveQueries. Option A is correct because ConcurrencyScalingActiveQueries indicates queries running on concurrency scaling clusters. Option B is wrong because WLMQueueLength shows queue wait, not concurrency scaling. Option C is wrong because QueryDuration measures query execution time. Option D is wrong because DiskSpaceUsage is for storage, not concurrency.

Answer

WLMQueueLength

Answer

DiskSpaceUsage

Answer

QueryDuration

Question 12

A company has an Amazon DynamoDB table with auto scaling enabled. During a traffic spike, the application experiences high write latencies. Which action should the company take to troubleshoot the latency issue?

Accepted Answer

Monitor the ThrottledWriteEvents metric in CloudWatch.. Option B is correct because CloudWatch metrics for ThrottledWriteEvents help identify if auto scaling is keeping up. Option A is wrong because disabling auto scaling may cause throttling. Option C is wrong because changing to on-demand may not be cost-effective and is not a troubleshooting step. Option D is wrong because increasing read capacity does not affect write latency.

Answer

Switch the table to on-demand capacity mode.

Answer

Disable auto scaling and manually increase write capacity.

Answer

Increase the read capacity of the table.

Question 13

A company is running an Amazon RDS for Oracle database in Multi-AZ. The primary instance fails over unexpectedly. The DBA wants to determine the cause of the failover. What should the DBA do?

Accepted Answer

View the RDS events in the AWS Management Console.. Option C is correct because RDS events log failover reasons. Option A is wrong because Enhanced Monitoring does not capture failover events. Option B is wrong because CloudTrail logs API calls, not failover reasons. Option D is wrong because error logs may not include failover cause.

Answer

Review the Enhanced Monitoring metrics for the primary instance.

Answer

Query the database error logs for the failover time.

Answer

Check AWS CloudTrail for any database-related API calls.

Question 14

A company is using Amazon ElastiCache for Redis as a caching layer. The application performance degrades when cache misses increase. Which metric should be monitored to track the cache hit rate?

Accepted Answer

CacheHits and CacheMisses. Option D is correct because CacheHits and CacheMisses together give the hit rate. Option A is wrong because CPUUtilization is for resource usage. Option B is wrong because Evictions indicates memory pressure, not hit rate. Option C is wrong because CurrConnections shows active connections.

Answer

CurrConnections

Answer

CPUUtilization

Answer

Evictions

Question 15

A database administrator notices that an Amazon RDS for MySQL DB instance is using more storage than expected. Which metric should be monitored to troubleshoot storage usage?

Accepted Answer

FreeStorageSpace. Option B is correct because FreeStorageSpace indicates remaining capacity. Option A is wrong because DatabaseConnections is about connections. Option C is wrong because ReadIOPS measures I/O operations. Option D is wrong because NetworkThroughput measures network traffic.

Answer

DatabaseConnections

Answer

ReadIOPS

Answer

NetworkThroughput