DBS-C01 Monitoring and Troubleshooting Practice Test 6 — 15 Questions

Question 1

A company is running an Amazon DocumentDB cluster. The application is experiencing high write latency. The cluster has a single instance. What should be done to identify the cause of the latency?

Accepted Answer

Enable Performance Insights and review the top wait events.. Option A is correct because enabling Performance Insights helps identify slow queries. Option B is wrong because adding a replica does not diagnose latency. Option C is wrong because increasing instance size is a reactive step. Option D is wrong because changing storage type may not address latency.

Answer

Upgrade the instance to a larger size.

Answer

Add a replica to distribute the write load.

Answer

Change the storage type to Provisioned IOPS.

Question 2

Which TWO metrics should be monitored to troubleshoot an Amazon RDS for PostgreSQL database that is experiencing high connection count and connection timeouts?

Accepted Answer

DatabaseConnections. Options B and D are correct. DatabaseConnections shows current connections, and BurstBalance helps understand if I/O is throttled. Option A is wrong because SwapUsage is not a standard RDS metric. Option C is wrong because ReadLatency is about I/O latency, not connections. Option E is wrong because NetworkTransmitThroughput is about network, not connections.

Answer

NetworkTransmitThroughput

Answer

SwapUsage

Answer

ReadLatency

Question 3

Which THREE steps should be taken to troubleshoot an Amazon DynamoDB table that is experiencing high read latency?

Accepted Answer

Review the table's partition distribution using DynamoDB metrics.. Option A is correct because high read latency in DynamoDB can result from uneven partition distribution, where a 'hot' partition receives more read requests than others, causing throttling or increased latency. By reviewing the table's partition distribution using CloudWatch metrics like `ConsumedReadCapacityUnits` per partition, you can identify skewed access patterns and address them with strategies like partition key redesign or adaptive capacity.

Answer

Increase the write capacity of the table.

Answer

Disable auto scaling to prevent unexpected capacity changes.

Question 4

Which TWO CloudWatch metrics should be monitored to determine if an Amazon Aurora MySQL DB cluster has sufficient I/O capacity?

Accepted Answer

ReadIOPS. Options B and D are correct. ReadIOPS and WriteIOPS show actual I/O operations. Option A is wrong because CPUUtilization is about CPU. Option C is wrong because DatabaseConnections is about connections. Option E is wrong because FreeableMemory is about memory.

Answer

FreeableMemory

Answer

CPUUtilization

Answer

DatabaseConnections

Question 5

A company is experiencing increased latency on their RDS for PostgreSQL instance. The CloudWatch metrics show high ReadIOPS but low CPU utilization. Which action is MOST likely to resolve the issue?

Accepted Answer

Increase the instance size or switch to a gp3 volume. Option C is correct because increasing the instance size or switching to a storage-optimized instance reduces I/O latency. Option A is wrong because Aurora is not the same as PostgreSQL. Option B is wrong because Multi-AZ does not improve performance. Option D is wrong because enabling auto-scaling only scales storage, not performance.

Answer

Migrate the database to Amazon Aurora PostgreSQL

Answer

Enable Multi-AZ deployment

Answer

Enable storage auto-scaling

Question 6

A database specialist notices that an RDS MySQL instance's FreeableMemory metric is consistently below 100 MB. Which monitoring tool should be used to identify the queries consuming the most memory?

Accepted Answer

Performance Insights. Option B is correct because Performance Insights shows detailed query-level performance. Option A is wrong because CloudWatch Logs are for log files. Option C is wrong because CloudTrail is for API calls. Option D is wrong because S3 does not monitor RDS memory.

Answer

Amazon S3 access logs

Answer

AWS CloudTrail

Answer

CloudWatch Logs

Question 7

A team is troubleshooting a DynamoDB table that has high read latency. The table uses on-demand capacity and has a global secondary index (GSI). Which configuration is MOST likely causing the issue?

Accepted Answer

The GSI has provisioned capacity set too low. Option A is correct because an under-provisioned GSI can throttle reads even if the base table uses on-demand. Option B is wrong because on-demand handles bursts. Option C is wrong because TTL does not affect read latency. Option D is wrong because DynamoDB Accelerator (DAX) reduces latency, not increases.

Answer

Time-to-Live (TTL) is enabled

Answer

DAX is enabled for the table

Answer

The table uses on-demand capacity

Question 8

A company's RDS for SQL Server instance is frequently running out of disk space. The instance uses General Purpose SSD (gp2) storage. Which monitoring step will help identify the root cause?

Accepted Answer

Monitor FreeStorageSpace and BinaryLogUsage metrics. Option D is correct because monitoring FreeStorageSpace and transaction log usage reveals what consumes space. Option A is wrong because backup storage is separate. Option B is wrong because Enhanced Monitoring shows OS metrics, not disk usage by database. Option C is wrong because CloudTrail is for API activity.

Answer

Review CloudTrail logs for API calls

Answer

Monitor BackupStorageUsed metric

Answer

Enable Enhanced Monitoring

Question 9

A developer reports that an application's write requests to a DynamoDB table are failing with ProvisionedThroughputExceededException. The table uses provisioned capacity. Which immediate action will resolve the issue?

Accepted Answer

Implement exponential backoff in the application. Option C is correct because implementing exponential backoff reduces request rate temporarily. Option A is wrong because switching to on-demand takes 30 minutes. Option B is wrong because deleting GSI does not help writes to main table. Option D is wrong because DAX caches reads, not writes.

Answer

Switch the table to on-demand capacity

Answer

Enable DynamoDB Accelerator (DAX)

Answer

Delete all global secondary indexes

Question 10

A company notices that its Aurora MySQL cluster has a high number of locks and deadlocks. The application uses read replicas for read scaling. What is the MOST likely cause?

Accepted Answer

Long-running transactions on the writer instance. Option B is correct because long-running transactions on the writer hold locks, increasing deadlocks. Option A is wrong because read replicas do not cause locks on writer. Option C is wrong because different instance sizes do not cause deadlocks. Option D is wrong because Performance Insights is diagnostic, not a cause.

Answer

Performance Insights is enabled

Answer

The writer and reader instances are of different sizes

Answer

Read replicas are performing write operations

Question 11

A company is using Amazon ElastiCache for Redis as a caching layer for a web application. Users report that some cached data is missing, causing slower responses. Which ElastiCache feature should be checked first to understand key evictions?

Accepted Answer

Evictions metric in CloudWatch. Option A is correct because Evictions metric shows how many keys are evicted due to memory pressure. Option B is wrong because CacheHits shows hits, not evictions. Option C is wrong because ReplicationLag is for replication. Option D is wrong because CPUUtilization does not directly show evictions.

Answer

ReplicationLag metric

Answer

CPUUtilization metric

Answer

CacheHits metric in CloudWatch

Question 12

A database administrator wants to receive an alert when an RDS instance's storage space drops below 10% of total allocated storage. Which AWS service should be used to set up this alert?

Accepted Answer

Amazon CloudWatch Alarms. Option B is correct because CloudWatch Alarms can trigger on FreeStorageSpace metric. Option A is wrong because SNS is a notification service, not monitor. Option C is wrong because CloudTrail is for API activity. Option D is wrong because Config tracks configuration changes.

Answer

Amazon SNS

Answer

AWS CloudTrail

Answer

AWS Config

Question 13

A company's DynamoDB table uses provisioned capacity and has a global table for disaster recovery. Write requests to the replica region are failing with ProvisionedThroughputExceededException even though the replica table shows low consumed capacity. What is the MOST likely cause?

Accepted Answer

The replica table's write capacity is insufficient for replication writes. Option D is correct because replicas have independent capacity; if replication writes exceed provisioned capacity, throttling occurs. Option A is wrong because burst capacity is not relevant to throttling. Option B is wrong because auto-scaling doesn't cause throttling. Option C is wrong because DAX is for reads.

Answer

Auto-scaling is disabled on the replica table

Answer

The replica table is exhausting its burst capacity

Answer

DAX is enabled on the replica table

Question 14

Which TWO metrics should be monitored to detect a memory leak in an RDS for Oracle instance? (Choose 2.)

Accepted Answer

SwapUsage. Options A and D are correct because FreeableMemory shows available memory, and SwapUsage indicates when the OS uses swap due to memory pressure, both signs of a memory leak. Option B is wrong because DatabaseConnections does not directly indicate memory leak. Option C is wrong because ReadIOPS relates to I/O, not memory. Option E is wrong because CPUUtilization may be high but not specific to memory leak.

Answer

DatabaseConnections

Answer

CPUUtilization

Answer

ReadIOPS

Question 15

Which THREE actions should be taken to troubleshoot an Amazon RDS for PostgreSQL instance that is unresponsive? (Choose 3.)

Accepted Answer

Verify that the security group allows inbound traffic on the database port. Options A, C, and D are correct because checking logs, verifying security groups, and reviewing metrics are standard initial steps. Option B is wrong because rebooting without diagnostics may lose evidence. Option E is wrong because modifying instance class without cause may not help and could be disruptive.

Answer

Reboot the DB instance immediately

Answer

Modify the DB instance to a larger instance class