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

Question 1

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?

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

Accepted Answer

Enable Enhanced Monitoring to identify the source of high CPU usage.. 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 2

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

ThrottledRequests. ThrottledRequests is a CloudWatch metric that directly counts the number of requests that were throttled due to exceeding provisioned throughput. For troubleshooting throttling issues, this metric provides immediate visibility into when throttling occurs. ConsumedWriteCapacityUnits (option D) shows capacity usage but does not directly indicate throttling; high consumption may lead to throttling but is not a direct measure. SuccessfulRequestLatency (option B) measures latency, not throttling, and UserErrors (option C) tracks client-side errors like invalid parameters, not capacity-related throttling.

Answer

SuccessfulRequestLatency

Answer

UserErrors

Answer

ConsumedWriteCapacityUnits

Question 3

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.. Performance Insights with the 'db.sql_tokenized' dimension allows database administrators to group and analyze database connections by user and application, helping identify the source of high connection counts. Option A (CloudTrail) logs API calls, not database-level logins. Option C (Enhanced Monitoring) provides OS-level metrics like connection count but does not break down by user or application. Option D (VPC Flow Logs) captures network traffic metadata, not database connection details.

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 4

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. ConcurrencyScalingActiveQueries measures the number of queries currently running on concurrency scaling clusters, helping identify if queries are waiting due to concurrency scaling. Option A is incorrect because WLMQueueLength indicates queries waiting in the workload management queue, not necessarily due to concurrency scaling. Option B is incorrect because DiskSpaceUsage tracks storage consumption, not query waiting. Option C is incorrect because QueryDuration measures execution time but does not indicate waiting for concurrency scaling resources.

Answer

WLMQueueLength

Answer

DiskSpaceUsage

Answer

QueryDuration

Question 5

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.. ThrottledWriteEvents metric indicates write requests that were throttled due to exceeding provisioned capacity. If this metric spikes during traffic spikes, it suggests that auto scaling is not scaling fast enough, leading to high write latencies. Option B is incorrect because switching to on-demand is a remediation, not a troubleshooting step; it does not help identify the root cause. Option C is incorrect because disabling auto scaling and manually increasing capacity might solve the issue temporarily but is not a troubleshooting approach; it bypasses auto scaling logic. Option D is incorrect because read capacity does not affect write latencies.

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 6

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

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 7

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. CacheHits and CacheMisses. The cache hit rate is calculated as CacheHits / (CacheHits + CacheMisses), so monitoring both metrics is essential. Option A (CurrConnections) tracks active connections, not hit rate. Option C (CPUUtilization) reflects resource usage. Option D (Evictions) indicates memory pressure but does not directly measure hit rate.

Answer

CurrConnections

Answer

CPUUtilization

Answer

Evictions

Question 8

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. FreeStorageSpace directly indicates the available storage remaining on the DB instance, which is key to troubleshooting storage usage. Option B is incorrect because DatabaseConnections measures the number of client connections, not storage. Option C is incorrect because ReadIOPS measures input/output operations per second, not storage capacity. Option D is incorrect because NetworkThroughput measures data transfer rates, not storage.

Answer

DatabaseConnections

Answer

ReadIOPS

Answer

NetworkThroughput

Question 9

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.. Enabling Performance Insights for Amazon DocumentDB allows you to monitor the database load and review top wait events, which helps identify the specific causes of high write latency, such as lock contention or I/O bottlenecks. Option A is wrong because simply upgrading to a larger instance size addresses symptoms but does not identify the root cause. Option C is wrong because adding a replica does not reduce write latency on the primary instance; it only offloads read traffic. Option D is wrong because changing to Provisioned IOPS may improve I/O performance but does not diagnose the underlying issue causing 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 10

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 A and C are correct. DatabaseConnections directly shows the number of concurrent connections to the RDS instance, helping monitor connection count. BurstBalance indicates whether the instance has exhausted its I/O burst credits; if it drops, I/O performance degrades and can cause connection timeouts. Option B (NetworkTransmitThroughput) measures network traffic, not connections. Option D (SwapUsage) tracks memory swapping, which is not a standard RDS metric and does not directly relate to connection timeouts. Option E (ReadLatency) measures I/O read latency, which can affect performance but is not a primary metric for high connection count or connection timeouts.

Answer

NetworkTransmitThroughput

Answer

SwapUsage

Answer

ReadLatency

Question 11

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.. 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 12

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

Accepted Answer

ReadIOPS. The correct metrics to monitor for sufficient I/O capacity are ReadIOPS (Option A) and WriteIOPS (Option B). These metrics represent the actual number of read and write I/O operations per second. If the cluster is approaching the maximum IOPS limit of the underlying storage, increasing I/O capacity may be needed. Option C (FreeableMemory) is related to memory, not I/O. Option D (CPUUtilization) measures CPU usage, not I/O. Option E (DatabaseConnections) tracks connections, not I/O capacity.

Answer

FreeableMemory

Answer

CPUUtilization

Answer

DatabaseConnections

Question 13

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. High ReadIOPS with low CPU indicates an I/O bottleneck. Increasing the instance size provides more dedicated IOPS, and switching to gp3 volume offers better baseline performance and throughput compared to gp2. Option A is incorrect because migrating to Aurora does not directly address the I/O bottleneck and involves additional considerations. Option C is incorrect because Multi-AZ provides high availability, not improved performance. Option D is incorrect because storage auto-scaling only increases storage capacity, not IOPS or throughput.

Answer

Migrate the database to Amazon Aurora PostgreSQL

Answer

Enable Multi-AZ deployment

Answer

Enable storage auto-scaling

Question 14

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. Performance Insights provides detailed query-level performance metrics, including memory consumption per query, which helps identify the queries consuming the most memory on an RDS MySQL instance. Option B is incorrect because Amazon S3 access logs record requests made to S3 buckets, not RDS memory usage. Option C is incorrect because AWS CloudTrail logs API calls for auditing, not database memory. Option D is incorrect because CloudWatch Logs can store logs but do not provide query-level memory analysis.

Answer

Amazon S3 access logs

Answer

AWS CloudTrail

Answer

CloudWatch Logs

Question 15

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. An under-provisioned GSI can throttle reads even if the base table uses on-demand. Option B is wrong because TTL does not affect read latency. Option C is wrong because DAX reduces latency, not increases. Option D is wrong because on-demand capacity handles bursts and does not cause high latency.

Answer

Time-to-Live (TTL) is enabled

Answer

DAX is enabled for the table

Answer

The table uses on-demand capacity