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

Question 1

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 THREE metrics should be reviewed in CloudWatch? (Select THREE.)

Accepted Answer

ConsumedWriteCapacityUnits. Option A is correct because 'ThrottledWriteRequests' directly indicates throttling. Option B is correct because 'WriteThrottleEvents' is another metric for throttling events. Option C is correct because 'ConsumedWriteCapacityUnits' helps understand if provisioned capacity is being fully used. Option D is wrong because 'ReadThrottleEvents' is for reads, not writes. Option E is wrong because 'SuccessfulRequestLatency' measures latency, not throttling.

Answer

ReadThrottleEvents

Answer

SuccessfulRequestLatency

Question 2

A database specialist is troubleshooting an Amazon RDS for PostgreSQL instance that has high replication lag between the primary and a read replica. Which TWO metrics should the specialist review to identify the cause? (Select TWO.)

Accepted Answer

ReadIOPS on the replica. Option A is correct because 'ReplicaLag' directly measures the lag. Option B is correct because 'ReadIOPS' can indicate heavy read activity on the replica that may cause lag. Option C is wrong because 'WriteIOPS' on the primary does not directly indicate replica lag. Option D is wrong because 'DatabaseConnections' is about connections, not replication. Option E is wrong because 'NetworkThroughput' is not a direct indicator of replication lag.

Answer

WriteIOPS on the primary

Answer

DatabaseConnections on the primary

Answer

NetworkThroughput between primary and replica

Question 3

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. Option C is correct because Performance Insights provides a database performance tuning and monitoring feature that allows you to assess the load on your database and determine when and where to take action. Option A is wrong because CloudWatch Logs does not capture query-level performance. Option B is wrong because CloudTrail tracks API activity, not database queries. Option D is wrong because RDS Enhanced Monitoring provides OS-level metrics, not query-level metrics.

Answer

Amazon CloudWatch Logs

Answer

Amazon RDS Enhanced Monitoring

Answer

AWS CloudTrail

Question 4

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. Option B is correct because DynamoDB Auto Scaling adjusts the provisioned throughput automatically in response to traffic patterns, reducing throttling. Option A is wrong because switching to eventually consistent reads may reduce throttling but changes the consistency model, which may not be acceptable. Option C is wrong because increasing read capacity is a manual action and not efficient. 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 5

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. Option D is correct because 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 RDS Enhanced Monitoring provides OS-level metrics, not log file metrics. Option C is wrong because S3 is a storage service, not a monitoring service.

Answer

AWS CloudTrail

Answer

Amazon S3

Answer

Amazon RDS Enhanced Monitoring

Question 6

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

Answer

Amazon RDS Performance Insights

Answer

Amazon CloudWatch

Answer

AWS CloudTrail

Question 7

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. Option A is correct because SVV_TABLE_INFO contains the unsorted and tombstone information needed. Option B is wrong because STL_QUERY contains query logs. Option C is wrong because STV_TBL_PERM contains permanent table information but not vacuum metrics. Option D is wrong because PG_TABLE_DEF contains table definitions.

Answer

STL_QUERY

Answer

STV_TBL_PERM

Answer

PG_TABLE_DEF

Question 8

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. Option B is correct because ThrottlingException occurs when the request rate exceeds the provisioned throughput capacity. Option A is wrong because eventually consistent reads consume half the read capacity units, so they are less likely to cause throttling. Option C is wrong because network issues would cause timeout errors, not throttling. Option D is wrong because incorrect table name would cause ResourceNotFoundException.

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 9

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. Option B is correct because Evictions metric shows the number of keys evicted due to memory pressure. Option A is wrong because CacheHits shows successful retrievals. Option C is wrong because CurrItems shows the current number of items, not evictions. Option D is wrong because SwapUsage shows swap usage, not evictions.

Answer

CacheHits

Answer

SwapUsage

Answer

CurrItems

Question 10

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. Option C is correct because INNODB_LOCKS shows current locks and InnoDB lock conflicts. Option A is wrong because PERFORMANCE_SCHEMA provides performance data but not specifically locks. Option B is wrong because INFORMATION_SCHEMA.PROCESSLIST shows current processes but not lock details. Option D is wrong because INFORMATION_SCHEMA.TABLES shows table metadata.

Answer

information_schema.TABLES

Answer

information_schema.PROCESSLIST

Answer

performance_schema.events_waits_current

Question 11

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. Option A is correct because checking DB instance logs can reveal connection issues like authentication failures or max connections reached. Option B is wrong because rebooting may not resolve the underlying issue. Option C is wrong because modifying the parameter group is not diagnostic. Option D is wrong because creating a snapshot is not a diagnostic step.

Answer

Reboot the DB instance

Answer

Modify the DB instance's parameter group

Answer

Create a DB snapshot

Question 12

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

Accepted Answer

Amazon CloudWatch Logs. Options A and B are correct. CloudWatch provides metrics like ConsumedReadCapacityUnits and can trigger alarms. CloudWatch Logs can capture log events but is not directly used for capacity alarms. CloudTrail records API calls, not capacity metrics. DynamoDB Auto Scaling adjusts capacity but does not monitor. AWS Config tracks configuration changes, not capacity.

Answer

Amazon DynamoDB Auto Scaling

Answer

AWS CloudTrail

Answer

AWS Config

Question 13

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 A, C, and D are correct. Using AWS Direct Connect provides a dedicated network connection, reducing latency. Compressing data reduces the amount of data transferred, mitigating latency impact. Using multiple threads parallelizes the data transfer, improving throughput. B is wrong because increasing the instance size does not reduce network latency. E is wrong because using a VPN may introduce additional overhead.

Answer

Increase the size of the RDS instance

Answer

Use AWS Site-to-Site VPN

Question 14

A company is using Amazon Redshift and has a query that is running slowly. The DBA wants to identify if the query is I/O-bound. Which TWO metrics from Amazon CloudWatch can indicate I/O-bound queries?

Accepted Answer

ReadIOPS. Options A and D are correct. ReadIOPS measures read operations per second, and ReadLatency measures the time for read operations; both are I/O metrics. WriteIOPS and WriteLatency are also I/O metrics but given the question, the correct ones are ReadIOPS and ReadLatency. Option C is wrong because CPUUtilization indicates CPU-bound, not I/O-bound. Option E is wrong because NetworkReceiveThroughput measures network throughput.

Answer

NetworkReceiveThroughput

Answer

CPUUtilization

Answer

WriteIOPS

Question 15

Refer to the exhibit. A DBA is troubleshooting an issue where an IAM user cannot view CloudWatch metrics for an RDS DB instance. The IAM policy attached to the user is shown above. What is the MOST likely reason the user cannot view the metrics?

Accepted Answer

The policy does not include cloudwatch:DescribeAlarms. Option D is correct because the policy is missing the 'rds:DescribeDBInstances' action for the specific DB instance resource, but the issue is about CloudWatch metrics. However, the policy includes 'cloudwatch:GetMetricStatistics' and 'cloudwatch:ListMetrics' with Resource '*', which should allow viewing metrics. But the user cannot view metrics, so the problem might be that the user lacks permission to describe the DB instance to get its identifier. Actually, the question is tricky: the policy allows describing DB instances, so the issue is likely that the user does not have permission to write to CloudWatch Logs? No. The exhibit shows an IAM policy that allows rds:DescribeDBInstances and cloudwatch:GetMetricStatistics and ListMetrics. The user should be able to view metrics. However, the DBA cannot view metrics; the most likely reason is that the policy does not include permission to view CloudWatch alarms or dashboards. But the question says "cannot view CloudWatch metrics", so the policy includes GetMetricStatistics. Option A is wrong because the policy includes that action. Option B is wrong because the resource is '*', so it's not restricted. Option C is wrong because the policy includes rds:DescribeDBInstances. Option D is correct because the user might need additional permissions like cloudwatch:DescribeAlarms or cloudwatch:GetMetricWidgetImage? Actually, the policy seems sufficient for viewing metrics via the console or API. But a common issue is that the console requires additional permissions like cloudwatch:DescribeAlarms for the Metrics page to load. So D is plausible.

Answer

The policy does not include rds:DescribeDBInstances

Answer

The policy uses a Resource element of '*' which is not allowed for CloudWatch

Answer

The policy does not include cloudwatch:GetMetricStatistics