DBS-C01 Monitoring and Troubleshooting Practice Test 3 — 15 Questions

Question 1

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?

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

Accepted Answer

ConcurrencyScalingActiveQueries. ConcurrencyScalingActiveQueries is the CloudWatch metric that specifically reports the number of queries actively running on concurrency-scaling clusters in Amazon Redshift. When this metric is non-zero, it indicates that queries have been routed to concurrency-scaling clusters because the main cluster's WLM queues were full, which directly explains increased query latency due to resource contention. Monitoring this metric lets you confirm whether concurrency scaling is being triggered and whether it is helping or hurting performance.

Answer

WLMQueueLength

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DiskSpaceUsage

Answer

QueryDuration

Question 2

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.. When a DynamoDB table with auto scaling experiences high write latencies during a traffic spike, the first troubleshooting step is to check the ThrottledWriteEvents metric in CloudWatch. This metric indicates whether write requests are being throttled due to exceeding provisioned write capacity, which would directly cause increased latency. Monitoring this metric helps determine if auto scaling is failing to keep up or if the table is hitting capacity limits.

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 3

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. DatabaseConnections (A) is correct because this CloudWatch metric reports the number of client connections currently open to the RDS for PostgreSQL instance, directly revealing whether the instance is hitting its max_connections limit and causing new connections to time out. BurstBalance (C) is correct because it shows the remaining I/O credits for gp2/EBS-backed storage; when BurstBalance is depleted, storage throughput collapses, queries and connection establishment slow down, and clients can time out waiting for the database to respond. NetworkTransmitThroughput (B) only measures outbound network traffic and does not indicate connection saturation or timeout causes. SwapUsage (D) can signal memory pressure but is not a primary indicator of connection count or connection timeouts. ReadLatency (E) reflects disk read performance and, while it can contribute to slow queries, it does not directly explain high connection counts or connection timeouts.

Answer

NetworkTransmitThroughput

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SwapUsage

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ReadLatency

Question 4

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 uneven partition distribution (hot partitions) causes individual partitions to exceed their 3,000 RCU / 1,000 WCU per-partition limits, so reviewing CloudWatch metrics like ConsumedReadCapacityUnits per partition helps identify hotspots driving read latency. Option C is correct because monitoring ConsumedReadCapacityUnits shows whether read throughput is approaching or exceeding provisioned capacity, which directly correlates with increased latency. Option E is correct because ThrottledReadEvents (and ReadThrottleEvents) indicates that read requests are being throttled due to insufficient capacity or hot partitions, a common root cause of high read latency. Option B is incorrect because increasing write capacity addresses write throughput, not read latency. Option D is incorrect because disabling auto scaling would remove the ability to adapt capacity to demand and could worsen throttling and latency.

Answer

Increase the write capacity of the table.

Answer

Disable auto scaling to prevent unexpected capacity changes.

Question 5

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

Accepted Answer

ReadIOPS. ReadIOPS (A) and WriteIOPS (B) are the correct metrics because they directly measure the number of read and write I/O operations per second that the Aurora MySQL cluster is performing against its storage layer, which is the definitive indicator of whether the provisioned I/O capacity is sufficient. If ReadIOPS or WriteIOPS consistently approach or saturate the cluster's available I/O throughput, the cluster lacks adequate I/O capacity and may need scaling or a larger instance class. FreeableMemory (C) reflects available RAM and relates to memory pressure, not I/O throughput. CPUUtilization (D) measures processor load, which can be affected by many factors and does not isolate storage I/O capacity. DatabaseConnections (E) counts active client sessions and indicates connection load, not the volume of disk I/O operations.

Answer

FreeableMemory

Answer

CPUUtilization

Answer

DatabaseConnections

Question 6

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 utilization indicates the bottleneck is storage I/O, not compute. Upgrading to a gp3 volume (or a larger instance with more EBS bandwidth) increases provisioned IOPS and throughput, directly relieving the read bottleneck. gp3 also decouples IOPS from volume size, allowing independent tuning.

Answer

Migrate the database to Amazon Aurora PostgreSQL

Answer

Enable Multi-AZ deployment

Answer

Enable storage auto-scaling

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. A global secondary index (GSI) in DynamoDB has its own provisioned capacity settings, even if the base table uses on-demand capacity. If the GSI is configured with provisioned capacity that is too low, it can throttle reads and cause high latency. This is a common misconfiguration because on-demand tables do not automatically apply on-demand to their GSIs; each GSI must be explicitly set to on-demand or provisioned with adequate capacity.

Answer

Time-to-Live (TTL) is enabled

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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

Enable Enhanced Monitoring. Enhanced Monitoring provides OS-level metrics at up to 1-second granularity, including disk I/O, file system usage, and per-process activity. For an RDS for SQL Server instance running out of disk space, this granularity is essential to pinpoint whether the space is consumed by data files, transaction logs, tempdb, or other OS-level processes. Standard CloudWatch metrics like FreeStorageSpace only show the symptom, not the cause. Thus, Enhanced Monitoring is the correct step to identify the root cause.

Answer

Review CloudTrail logs for API calls

Answer

Monitor FreeStorageSpace and BinaryLogUsage metrics

Answer

Monitor BackupStorageUsed metric

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. Implementing exponential backoff in the application is the correct immediate action because ProvisionedThroughputExceededException indicates the request rate exceeded the table's provisioned read/write capacity. Exponential backoff with jitter retries failed requests at increasing intervals, smoothing bursts and allowing the table to absorb traffic without dropping requests. This is the AWS-recommended best practice for handling throttling.

Answer

Switch the table to on-demand capacity

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Enable DynamoDB Accelerator (DAX)

Answer

Delete all global secondary indexes

Question 10

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. In DynamoDB global tables, writes made to a replica region are replicated to other regions, and those replication writes consume write capacity units (WCUs) on the destination replica tables. If the replica table's provisioned WCU is too low to absorb the replication traffic, the replica returns ProvisionedThroughputExceededException even though its own consumed capacity metric looks low — because replication writes are counted separately from application writes.

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 11

Which TWO settings should be verified when troubleshooting an RDS for MySQL instance that has a high number of aborted connections? (Choose 2.)

Accepted Answer

connect_timeout parameter. The connect_timeout parameter (option A) is correct because it defines how many seconds the server waits for a connection packet before aborting the connection; if clients or network paths are slow, a low connect_timeout causes connections to be aborted before completing the handshake, directly inflating the Aborted_connects counter. The max_allowed_packet parameter (option B) is correct because if a client sends a packet larger than this value, the server aborts the connection and increments Aborted_connects, so verifying it helps identify oversized-packet-related aborts. Option C (query_cache_type) affects query result caching, not connection establishment, so it does not explain aborted connections. Option D (binlog_retention_hours) controls binary log retention for point-in-time recovery and has no bearing on connection aborts. Option E (max_connections) causes 'Too many connections' errors and increments the Connection_errors_max_connections counter rather than Aborted_connects, so it is not the right setting to verify for this symptom.

Answer

query_cache_type parameter

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binlog_retention_hours parameter

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max_connections parameter

Question 12

A developer reports that an Amazon RDS for MySQL DB instance is experiencing high CPU utilization. You suspect a specific query is causing the issue. Which CloudWatch metric should you examine to confirm this?

Accepted Answer

CPUUtilization. CPUUtilization is the CloudWatch metric that directly measures the percentage of CPU used by the RDS instance. If a specific query is driving high CPU, this metric will show sustained elevated values, and it can be correlated with Performance Insights or slow query logs to identify the offending SQL. It is the primary metric to confirm CPU-bound query impact.

Answer

DatabaseConnections

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ReadLatency

Answer

FreeableMemory

Question 13

A company runs an Amazon RDS for PostgreSQL instance with Multi-AZ deployment. The primary DB instance fails unexpectedly and a failover occurs. Which action should be taken to minimize downtime during future failovers?

Accepted Answer

Configure an Amazon RDS Proxy to reduce failover time.. Amazon RDS Proxy maintains a connection pool and automatically routes connections to the new primary after failover, dramatically reducing the reconnection storm and application downtime. Without a proxy, applications must detect the DNS change and re-establish connections, which can take 60-120 seconds. RDS Proxy can cut that to single-digit seconds by keeping client connections alive and transparently redirecting them.

Answer

Increase the DB instance size to reduce failover time.

Answer

Create a read replica in the same region and promote it during failover.

Answer

Enable Multi-AZ deployment to automatically failover to the standby.

Question 14

A team is troubleshooting an Amazon DynamoDB table that is throttling write requests. The table has on-demand capacity mode enabled. Which of the following is the most likely cause of the throttling?

Accepted Answer

The write traffic exceeds the table's previous peak traffic by more than double.. In on-demand mode, DynamoDB automatically scales to previous peak traffic, but it cannot instantly double capacity. If write traffic exceeds the table's previous peak by more than 2x within a 30-minute window, the table will throttle until it has scaled up. This is the documented behavior for on-demand tables and is the most likely cause here.

Answer

The table has exceeded its provisioned write capacity units.

Answer

The table is not using adaptive capacity.

Answer

There is an active AWS Health event affecting the DynamoDB service.

Question 15

An administrator notices that the CloudWatch metric 'ReadLatency' for an Amazon RDS for SQL Server instance has increased significantly. Which of the following is the most likely cause?

Accepted Answer

The DB instance does not have enough provisioned IOPS.. ReadLatency measures the average time taken for a read operation from the database. If ReadLatency increases significantly, it often indicates that the storage subsystem is unable to keep up with the I/O demands. For RDS, provisioned IOPS (for EBS volumes) directly affects read performance. If the instance does not have enough provisioned IOPS, read operations will be slower, increasing ReadLatency. Therefore, insufficient provisioned IOPS is the most likely cause.

Answer

The DB instance is experiencing high CPU utilization.

Answer

The DB instance is running out of memory.

Answer

The DB instance is using a burstable instance class that has exhausted its credits.