DBS-C01 Monitoring and Troubleshooting Practice Test 17 — 15 Questions

Question 1

Refer to the exhibit. A DBA sees the above error log entries for an Amazon RDS for MySQL DB instance. Which action should the DBA take to resolve the 'Too many connections' error?

Accepted Answer

Modify the DB parameter group to increase max_connections. Option B is correct because increasing the max_connections parameter allows more concurrent connections. Option A is wrong because rebooting does not increase the connection limit. Option C is wrong because modifying the security group does not affect database connections. Option D is wrong because the error is not about authentication.

Answer

Reboot the DB instance

Answer

Modify the DB security group to allow more connections

Answer

Reset the DB instance master user password

Question 2

Refer to the exhibit. A developer is trying to query the ProductCatalog table using the 'Id' attribute. The query returns no results even though the developer knows data was inserted. What is the MOST likely cause?

Accepted Answer

The table contains no items. Option D is correct because the table has no items (ItemCount: 0). Option A is wrong because the table is active. Option B is wrong because provisioned throughput is not exceeded (ItemCount is 0). Option C is wrong because the attribute definition exists.

Answer

The provisioned throughput is exceeded

Answer

The attribute definition is missing the 'Id' attribute

Answer

The table is not in ACTIVE status

Question 3

A company is running a production Amazon RDS for MySQL DB instance. The application team reports intermittent connection timeouts. The DBA notices that the DB instance's CPU utilization spikes to 100% during these times. Which metric should be monitored to determine if the issue is due to a specific query?

Accepted Answer

Queries (engine-specific counter). Option D is correct because the RDS for MySQL engine-specific counter 'Queries' reflects the number of queries executed. Option A is wrong because DatabaseConnections shows connections, not query performance. Option B is wrong because ReadIOPS measures disk I/O, not query volume. Option C is wrong because NetworkThroughput measures network traffic.

Answer

DatabaseConnections

Answer

NetworkThroughput

Answer

ReadIOPS

Question 4

A company uses Amazon DynamoDB with global tables. During a regional failure, the application in the secondary region experiences higher latency and throttling. The DynamoDB table's WriteCapacityUnits are set to 10000 in both regions. Which action should be taken to reduce throttling during failover?

Accepted Answer

Enable DynamoDB auto scaling for write capacity in both regions. Option C is correct because enabling auto scaling allows DynamoDB to adjust capacity based on traffic patterns. Option A is wrong because increasing only the secondary region may not be sufficient without auto scaling. Option B is wrong because turning off global tables would prevent replication. Option D is wrong because switching to on-demand is expensive and not the best practice for predictable workloads.

Answer

Switch the table to on-demand capacity mode

Answer

Disable global tables and use application-level replication

Answer

Increase the write capacity of the secondary region to 20000

Question 5

A developer notices that an Amazon RDS for PostgreSQL DB instance is running low on free storage space. The instance has 100 GB of allocated storage. What is the recommended first step to troubleshoot this issue?

Accepted Answer

Check for unused indexes or table bloat using pg_repack or similar tools. Option B is correct because checking for unused indexes or bloat is a typical starting point for storage issues. Option A is wrong because modifying storage is a solution, not a troubleshooting step. Option C is wrong because deleting logs may not recover much space. Option D is wrong because enabling auto scaling is a preventive measure, not a troubleshooting step.

Answer

Enable storage auto scaling

Answer

Modify the DB instance to increase allocated storage

Answer

Delete the oldest transaction logs

Question 6

A company is running an Amazon Aurora MySQL-Compatible DB cluster. The application is experiencing increased latency during peak hours. The DB cluster's CPU utilization is at 40%, but the ReadReplicaLag metric is high. Which of the following is the most likely cause?

Accepted Answer

The writer instance is experiencing I/O bottlenecks, causing slow replication. Option A is correct because high replica lag indicates the replica is falling behind, often due to insufficient I/O capacity on the writer or replica. Option B is wrong because read replicas handle SELECT queries. Option C is wrong because binary log retention does not affect replica lag directly. Option D is wrong because the DB cluster parameter group is shared.

Answer

The read replica is receiving too many write requests

Answer

The DB cluster parameter group is misconfigured

Answer

The binary log retention period is too long

Question 7

A company is using Amazon DynamoDB Accelerator (DAX) to improve read performance. Recently, the cache hit ratio has dropped significantly. The application uses strongly consistent reads. What is the most likely cause of the low cache hit ratio?

Accepted Answer

The application is using strongly consistent reads, which bypass the DAX cache. Option C is correct because DAX caches eventually consistent reads, not strongly consistent reads. Option A is wrong because TTL affects item expiration but not the consistency model. Option B is wrong because write capacity does not directly affect cache hits. Option D is wrong because the DAX cluster size affects performance but not the consistency mismatch.

Answer

The DynamoDB table's write capacity is too low

Answer

The DAX cluster has too few nodes

Answer

The DAX cluster's TTL is set too low

Question 8

A database administrator is monitoring an Amazon RDS for SQL Server DB instance and notices that the FreeableMemory metric is consistently below 200 MB. Which of the following actions is most appropriate to mitigate performance issues?

Accepted Answer

Scale up the DB instance to a larger instance class with more memory. Option B is correct because low freeable memory can cause performance degradation; increasing allocated memory (by scaling up) helps. Option A is wrong because enabling automatic backups does not affect memory. Option C is wrong because modifying the maintenance window does not help. Option D is wrong because disabling logging is not a standard practice.

Answer

Modify the DB instance's maintenance window to off-peak hours

Answer

Disable the SQL Server Agent and error logging

Answer

Enable automatic backups with a shorter retention period

Question 9

A company is using Amazon Redshift for data warehousing. The query performance has degraded over time. The DBA suspects that the distribution style of large tables is suboptimal. Which Redshift system view should be queried to identify distribution skew?

Accepted Answer

SVV_DISKUSAGE. Option C is correct because SVV_DISKUSAGE provides information about disk usage per slice, which helps identify skew. Option A is wrong because STL_SCAN is for scan operations. Option B is wrong because STV_TBL_PERM shows permissions. Option D is wrong because PG_TABLE_DEF shows table definitions.

Answer

STL_SCAN

Answer

PG_TABLE_DEF

Answer

STV_TBL_PERM

Question 10

An application using Amazon DynamoDB is experiencing higher than expected read costs. The table uses on-demand capacity mode. The read pattern is mostly fetching small items (1 KB) using GetItem. Which of the following is the most cost-effective optimization?

Accepted Answer

Switch to eventually consistent reads for GetItem operations. Option A is correct because DynamoDB charges for read capacity units based on item size, and using GetItem with strongly consistent reads consumes 1 RCU for items up to 4 KB. Option B is wrong because changing to provisioned capacity may not be cost-effective with unpredictable traffic. Option C is wrong because compression is not natively supported. Option D is wrong because DAX adds cost and may not reduce RCU consumption if reads are strongly consistent.

Answer

Change the table to provisioned capacity mode with auto scaling

Answer

Compress the items using application-level compression

Answer

Use DAX to cache the read results

Question 11

A database administrator is troubleshooting a slow-running query on an Amazon RDS for MySQL DB instance. Which CloudWatch metric should be monitored to determine if the query is experiencing storage I/O bottlenecks?

Accepted Answer

ReadLatency and WriteLatency. Option A is correct because ReadLatency and WriteLatency indicate I/O performance. Option B is wrong because CPUUtilization measures processor usage. Option C is wrong because DatabaseConnections measures connections. Option D is wrong because NetworkThroughput measures network traffic.

Answer

CPUUtilization

Answer

NetworkThroughput

Answer

DatabaseConnections

Question 12

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

Accepted Answer

FreeableMemory. Options A and D are correct because FreeableMemory shows available memory, and SwapUsage indicates swapping, which occurs when memory is exhausted. Option B (NetworkThroughput) is not memory-related. Option C (ReadIOPS) is I/O-related. Option E (DatabaseConnections) is connection-related.

Answer

ReadIOPS

Answer

DatabaseConnections

Answer

NetworkThroughput

Question 13

Which THREE steps should be taken to troubleshoot high replica lag in an Amazon Aurora MySQL DB cluster? (Choose THREE.)

Accepted Answer

Review network latency between the writer and replica. Options B, D, and E are correct. Checking the replica's load (B), examining replication threads (D), and reviewing network latency (E) are common troubleshooting steps. Option A (increasing instance size) is a solution, not a troubleshooting step. Option C (disabling binary logging) would break replication.

Answer

Increase the instance size of the replica

Answer

Disable binary logging on the writer

Question 14

Which TWO CloudWatch Logs features can be used to monitor and troubleshoot Amazon RDS for SQL Server error logs? (Choose TWO.)

Accepted Answer

Setting metric filters to count error occurrences. Options A and C are correct because CloudWatch Logs can monitor error logs in real time and set metric filters for specific error patterns. Option B (S3 export) is for archiving, not real-time monitoring. Option D (CloudTrail) is for API activity, not database logs. Option E (X-Ray) is for tracing, not log monitoring.

Answer

Integrating with AWS X-Ray for trace analysis

Answer

Exporting logs to Amazon S3

Answer

Using AWS CloudTrail to capture log events

Question 15

A company uses Amazon RDS for MySQL with Multi-AZ deployment. The database experiences intermittent write latency spikes. CloudWatch shows elevated 'WriteLatency' and 'WriteIOPS' but normal 'CPUUtilization'. Which is the MOST likely cause?

Accepted Answer

The instance is exceeding the provisioned IOPS burst balance. Option D is correct because write spikes with high IOPS but low CPU often indicate storage performance issues like exceeding EBS burst balance. Option A is wrong because Multi-AZ replication does not cause write latency. Option B is wrong because read replica lag affects read, not write. Option C is wrong because parameter group changes require reboot and affect all operations, not intermittent.

Answer

A parameter group change was applied without rebooting

Answer

A read replica is being used for write operations

Answer

Multi-AZ replication is causing synchronous writes to the standby

DBS-C01 Monitoring and Troubleshooting Practice Test 17 — 15 Questions

Exhibit

DBS-C01 Monitoring and Troubleshooting Practice Test 17 — 15 Questions

Exhibit