DBS-C01 Monitoring and Troubleshooting Practice Test 16 — 15 Questions

Question 1

A database specialist is troubleshooting a slow Amazon RDS for PostgreSQL query. The specialist has enabled Performance Insights and sees that the database load is high. Which additional tool can provide detailed information about the specific queries causing the load?

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

Accepted Answer

Use Enhanced Monitoring to view OS-level metrics and correlate with performance insights.. Enhanced Monitoring provides OS-level metrics (CPU, memory, disk I/O, etc.), which when combined with Performance Insights' query-level details, gives a comprehensive view of database performance. Option A is wrong because VPC Flow Logs capture network traffic information, not query-specific details. Option B is wrong because CloudWatch Logs can analyze PostgreSQL error logs, but this does not provide detailed query-level load information. Option D is wrong because AWS CloudTrail records API calls, not database queries.

Answer

Use VPC Flow Logs to analyze network traffic to the database.

Answer

Use Amazon CloudWatch Logs to analyze the PostgreSQL error logs.

Answer

Use AWS CloudTrail to view database API calls.

Question 2

A database specialist is monitoring an Amazon RDS for MySQL instance and notices that the 'CPUUtilization' metric is consistently above 90%. Which TWO actions should the specialist take to investigate the issue? (Select TWO.)

Accepted Answer

Use Performance Insights to identify the queries that are consuming the most CPU.. Performance Insights identifies the queries that are consuming the most CPU, helping to locate the source of high CPU utilization. Option E is correct because Enhanced Monitoring provides OS-level metrics (e.g., CPU, memory, disk I/O) that help investigate the issue. Option A is incorrect because disabling the query cache does not help investigate CPU usage; it may even increase CPU load temporarily. Option C is incorrect because increasing the instance class is a remediation step, not an investigation action. Option D is incorrect because Multi-AZ does not distribute read load to a standby instance; the standby is only for failover, not for load distribution.

Answer

Disable the MySQL query cache to free up CPU.

Answer

Increase the instance class to provide more CPU resources.

Answer

Enable Multi-AZ to distribute the load to a standby instance.

Question 3

A company is using Amazon DynamoDB with provisioned capacity. The application is experiencing throttling on write requests. The database specialist needs to identify the cause. Which TWO metrics should be reviewed in CloudWatch? (Select TWO.)

Accepted Answer

ConsumedWriteCapacityUnits. 'ConsumedWriteCapacityUnits' shows the actual write capacity used, helping to determine if provisioned capacity is exceeded, which leads to throttling. Option B is correct because 'WriteThrottleEvents' directly indicates the number of throttled write requests. Option C is incorrect because 'ThrottledWriteRequests' is not a valid CloudWatch metric for DynamoDB; the correct metric for throttled writes is 'WriteThrottleEvents'. Option D is incorrect because 'ReadThrottleEvents' pertains to read throttling, not writes. Option E is incorrect because 'SuccessfulRequestLatency' measures latency, not throttling events.

Answer

ThrottledWriteRequests

Answer

ReadThrottleEvents

Answer

SuccessfulRequestLatency

Question 4

A database specialist is troubleshooting a slow Amazon RDS for PostgreSQL query. The specialist has enabled Performance Insights and sees that the database load is high. Which additional tool can provide detailed information about the specific queries causing the load?

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

Accepted Answer

ReadIOPS on the replica. High ReadIOPS on the read replica can indicate heavy read activity, which may cause replication lag as the replica struggles to apply changes fast enough. Option D is correct because ReplicaLag directly measures the time delay between the primary and replica, confirming the presence of lag. Option A is incorrect because WriteIOPS on the primary reflects write workload, not lag cause. Option C is incorrect because DatabaseConnections do not directly affect replication lag. Option E is incorrect because NetworkThroughput is not a metric that directly indicates replication lag; it could be a factor but is not a standard RDS metric for diagnosing lag.

Answer

WriteIOPS on the primary

Answer

DatabaseConnections on the primary

Answer

NetworkThroughput between primary and replica

Question 5

A company uses Amazon RDS for MySQL with Multi-AZ deployment. The database is experiencing increased latency and the application team reports slow queries. The DBA wants to identify the queries that consume the most resources. Which AWS service should be used to capture and analyze these queries?

Accepted Answer

Amazon RDS Performance Insights. Amazon RDS Performance Insights provides database performance tuning and monitoring with query-level metrics, enabling identification of resource-intensive queries. Option B is wrong because CloudWatch Logs collects log files but does not capture query-level performance. Option C is wrong because Enhanced Monitoring provides OS-level metrics (CPU, memory) but not query-level details. Option D is wrong because CloudTrail records AWS API activity, not database queries.

Answer

Amazon CloudWatch Logs

Answer

Amazon RDS Enhanced Monitoring

Answer

AWS CloudTrail

Question 6

A company is using Amazon DynamoDB for a high-traffic application. Users report occasional 'ProvisionedThroughputExceededException' errors. The application uses consistent reads and retries with exponential backoff. What is the MOST efficient way to handle these errors and reduce the number of retries?

Accepted Answer

Enable DynamoDB Auto Scaling for the table. DynamoDB Auto Scaling adjusts the provisioned throughput automatically in response to traffic patterns, reducing throttling and the need for retries. Option A is wrong because increasing read capacity manually is inefficient and does not adapt to fluctuating traffic. Option B is wrong because switching to eventually consistent reads changes the consistency model, which may not be acceptable for the application's requirements. Option D is wrong because increasing write capacity does not address read throttling.

Answer

Increase the provisioned read capacity units manually

Answer

Switch to eventually consistent reads

Answer

Increase the provisioned write capacity units manually

Question 7

A database administrator notices that the /var/log/mysql/error.log file on an Amazon RDS for MySQL DB instance is growing rapidly. The administrator wants to monitor the log file size and receive alerts when it exceeds a certain threshold. Which AWS service should be used to set up this monitoring?

Accepted Answer

Amazon CloudWatch Logs. CloudWatch Logs can monitor log file sizes and trigger alarms based on metric filters. Option A is wrong because CloudTrail does not monitor log file sizes. Option B is wrong because S3 is a storage service, not a monitoring service. Option C is wrong because RDS Enhanced Monitoring provides OS-level metrics, not log file metrics.

Answer

AWS CloudTrail

Answer

Amazon S3

Answer

Amazon RDS Enhanced Monitoring

Question 8

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database uses Oracle Data Guard for disaster recovery. Which AWS service should be used to monitor the replication lag between the source and target databases during migration?

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS DMS provides metrics for replication lag. Option A is wrong because Performance Insights does not monitor replication lag. Option C is wrong because CloudWatch can monitor DMS metrics but is not specific to Data Guard. Option D is wrong because CloudTrail does not monitor replication lag.

Answer

Amazon RDS Performance Insights

Answer

Amazon CloudWatch

Answer

AWS CloudTrail

Question 9

A company is using Amazon Redshift for data warehousing. The VACUUM operation is taking longer than expected, and the database administrator wants to identify the tables that require the most vacuuming effort. Which system table should be queried to find the percentage of deleted rows per table?

Accepted Answer

SVV_TABLE_INFO. (SVV_TABLE_INFO) is correct because this system table contains tombstone and unsorted statistics, including the percentage of deleted rows per table, which helps identify tables requiring vacuuming. Option A (STL_QUERY) is incorrect because it stores query execution logs, not table statistics. Option B (STV_TBL_PERM) is incorrect as it provides information about permanent table block allocations but not deleted row ratios. Option C (PG_TABLE_DEF) is incorrect because it holds table schema definitions only, not operational metrics.

Answer

STL_QUERY

Answer

STV_TBL_PERM

Answer

PG_TABLE_DEF

Question 10

A developer is troubleshooting an issue where an application using Amazon DynamoDB is receiving occasional 'ThrottlingException' errors. The application uses eventually consistent reads. What is the MOST likely cause of this error?

Accepted Answer

The read capacity units are set too low for the current traffic pattern. ThrottlingException occurs when the request rate exceeds the provisioned throughput capacity. Option A is incorrect because an incorrect table name would result in a ResourceNotFoundException, not a ThrottlingException. Option C is incorrect because eventually consistent reads consume half the read capacity units compared to strongly consistent reads, making them less likely to cause throttling. Option D is incorrect because network connectivity issues would typically cause timeout or connection errors, not ThrottlingException.

Answer

The application is using an incorrect table name

Answer

The application is using eventually consistent reads instead of strongly consistent reads

Answer

There is a network connectivity issue between the application and DynamoDB

Question 11

A company is using Amazon ElastiCache for Redis as a caching layer for a web application. The application's response time has increased, and the operations team suspects that cache evictions are occurring frequently. Which ElastiCache metric should be monitored to confirm cache evictions?

Accepted Answer

Evictions. The Evictions metric in Amazon ElastiCache for Redis shows the number of keys evicted due to memory pressure. Option A (CacheHits) is wrong because it indicates successful key retrievals, not evictions. Option B (SwapUsage) is wrong because it shows the amount of swap space used, not eviction count. Option D (CurrItems) is wrong because it shows the current number of items in the cache, not evictions.

Answer

CacheHits

Answer

SwapUsage

Answer

CurrItems

Question 12

A company is using Amazon Aurora MySQL. The database performance has degraded, and the DBA wants to identify the queries that are waiting for locks. Which system table should be queried to find information about locking conflicts?

Accepted Answer

information_schema.INNODB_LOCKS. Information_schema.INNODB_LOCKS. This table shows current locks held by InnoDB transactions, including lock type, mode, and which transactions are waiting for locks. Option A (information_schema.TABLES) provides metadata about tables, not locks. Option B (information_schema.PROCESSLIST) shows current running processes but not lock details. Option C (performance_schema.events_waits_current) shows current wait events but is not specific to InnoDB lock conflicts; INNODB_LOCKS is the correct source for identifying locking conflicts in Aurora MySQL.

Answer

information_schema.TABLES

Answer

information_schema.PROCESSLIST

Answer

performance_schema.events_waits_current

Question 13

A database administrator is troubleshooting an issue where an Amazon RDS for PostgreSQL DB instance is not allowing connections. The administrator checks the security group and network ACLs, and they are correctly configured. What is the next step to diagnose the issue?

Accepted Answer

Review the DB instance error logs in Amazon CloudWatch. Reviewing the DB instance error logs in Amazon CloudWatch can reveal connection issues such as authentication failures, SSL/TLS errors, or the maximum number of connections being reached. This is a direct diagnostic step. Option A is incorrect because rebooting may temporarily resolve a connection issue but does not help identify the root cause. Option B is incorrect because modifying the parameter group changes configuration settings, which is not a diagnostic action for existing connection problems. Option C is incorrect because creating a snapshot is for backup and recovery, not for troubleshooting current connectivity.

Answer

Reboot the DB instance

Answer

Modify the DB instance's parameter group

Answer

Create a DB snapshot

Question 14

A company is using Amazon DynamoDB and wants to monitor the read/write capacity utilization of a table. Which ONE AWS service can be used to set up alarms for capacity consumption?

Accepted Answer

Amazon CloudWatch. Amazon CloudWatch (D) is the primary service for monitoring DynamoDB capacity metrics such as ConsumedReadCapacityUnits and ConsumedWriteCapacityUnits, and it can trigger alarms based on thresholds. Option C (Amazon CloudWatch Logs) is not used for direct capacity monitoring because DynamoDB does not emit capacity consumption logs; those metrics are available only through CloudWatch Metrics. DynamoDB Auto Scaling (A) adjusts capacity but does not monitor or alarm. AWS CloudTrail (B) records API calls, not capacity metrics. AWS Config (E) tracks configuration changes, not utilization.

Answer

Amazon DynamoDB Auto Scaling

Answer

AWS CloudTrail

Answer

Amazon CloudWatch Logs

Answer

AWS Config

Question 15

A company is migrating an on-premises SQL Server database to Amazon RDS for SQL Server. During the migration, the DBA notices that the network latency between the source and target is high. Which THREE actions can the DBA take to reduce the impact of network latency on migration performance?

Accepted Answer

Use multiple parallel tasks in AWS DMS. Options B, C, and D are correct. Using multiple parallel tasks in AWS DMS (option B) improves throughput by transferring data in parallel. Using AWS Direct Connect (option C) provides a dedicated, low-latency network connection. Enabling data compression (option D) reduces the amount of data transferred, mitigating latency impact. Option A is incorrect because increasing the RDS instance size does not reduce network latency; it only affects database processing capacity. Option E is incorrect because using a VPN can add overhead and may not reduce latency.

Answer

Increase the size of the RDS instance

Answer

Use AWS Site-to-Site VPN