DBS-C01 Practice Test 31 — 15 Questions

Question 1

A company is planning to migrate its on-premises Oracle database to Amazon RDS for Oracle. The database uses Oracle Data Guard for disaster recovery. Which TWO AWS services can be used to assess the database and plan the migration? (Choose TWO.)

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

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) can migrate the Oracle database to RDS, while the AWS Schema Conversion Tool (SCT) assesses the source database and converts the schema to target format. Option A (AWS Migration Hub) tracks migrations but does not assess databases. Option B (CloudEndure Disaster Recovery) is for server-level disaster recovery, not database assessment. Option C (AWS Snowball) is for offline data transfer, not assessment or migration planning.

Answer

AWS Migration Hub

Answer

CloudEndure Disaster Recovery

Answer

AWS Snowball

Question 2

Which TWO database design considerations are critical when migrating a high-traffic e-commerce website from Oracle to Amazon Aurora MySQL? (Choose 2.)

Accepted Answer

Review and adapt application SQL queries for MySQL compatibility. Oracle and MySQL use different SQL dialects, data types, and functions. Migrating a high-traffic e-commerce application requires reviewing and adapting all SQL queries to ensure compatibility with Aurora MySQL, including handling Oracle-specific features like sequences, hierarchical queries (CONNECT BY), and PL/SQL stored procedures. Failure to do so will cause runtime errors or degraded performance.

Answer

Enable eventual consistency for read replicas to reduce latency

Answer

Use Aurora Multi-Master to distribute write load

Answer

Compress all tables to reduce storage costs

Question 3

A company is using Amazon DynamoDB with a TTL attribute to automatically delete expired items. The security team is concerned that deleted items might still be recoverable from backups. They need to ensure that once an item is deleted by TTL, it is not included in future on-demand backups. Additionally, they want to ensure that the TTL deletion itself is logged for audit purposes. What should they do?

Accepted Answer

Enable DynamoDB Streams on the table and use a Lambda function to log TTL deletion events to CloudWatch Logs.. DynamoDB Streams can capture TTL deletions as 'REMOVE' events. By processing these events with a Lambda function and logging them to CloudWatch Logs, the security team can audit TTL deletions. On-demand backups reflect the current table state, so items deleted by TTL before the backup is taken will not be included. Option A is incorrect because disabling TTL and implementing a custom deletion process adds complexity and may not be as efficient. Option C is incorrect because CloudTrail logs the UpdateTimeToLive API call (control plane), not the actual TTL deletions (data plane). Option D is incorrect because CloudTrail data events for DynamoDB capture GetItem, PutItem, etc., but not TTL deletions.

Answer

Disable TTL and implement a custom deletion process that logs deletions before removing items.

Answer

Use AWS CloudTrail to log the UpdateTimeToLive API call.

Answer

Enable AWS CloudTrail data events for DynamoDB to capture TTL deletions.

Question 4

Which THREE metrics should be monitored in Amazon CloudWatch to detect a potential memory leak in an Amazon RDS for SQL Server instance? (Choose three.)

Accepted Answer

DatabaseConnections. Options A, D, and E are correct. DatabaseConnections can indicate a memory leak if connections are not closed, consuming memory. SwapUsage indicates memory pressure when physical memory is insufficient. FreeableMemory shows available memory; a decreasing trend may suggest a leak. Option B is incorrect because CPUUtilization is not a direct memory metric. Option C is incorrect because ReadIOPS relates to I/O operations, not memory.

Answer

CPUUtilization

Answer

ReadIOPS

Question 5

A database administrator is troubleshooting a performance issue on an Amazon Aurora MySQL cluster. The application is experiencing high latency on write operations. Which TWO CloudWatch metrics should the administrator analyze to identify the root cause?

Accepted Answer

DMLThroughput. The correct metrics to analyze for high write latency are DMLThroughput and CommitLatency. DMLThroughput measures the rate of Data Manipulation Language operations, including INSERT, UPDATE, and DELETE, which are write-intensive. High DMLThroughput may indicate excessive write operations. CommitLatency measures the time taken to commit transactions; high commit latency directly contributes to write latency. The other options are not directly related to write performance.

Answer

ReadLatency

Answer

SelectLatency

Answer

FreeableMemory

Question 6

An administrator is troubleshooting an Amazon RDS for PostgreSQL instance that is experiencing high CPU utilization. The administrator has enabled Performance Insights. Which metric should be examined first to identify the queries consuming the most CPU?

Accepted Answer

db.load.avg. The correct metric to examine first is 'db.load.avg' (Option C). In Amazon RDS Performance Insights, 'db.load.avg' represents the average number of active sessions, which directly correlates with CPU utilization. A high value indicates queries that are consuming significant CPU resources. Option A ('db.sessions') is not a standard Performance Insights metric. Option B ('db.cpu.avg') does not exist in Performance Insights. Option D ('db.bytes_sent') is a network metric unrelated to CPU usage.

Answer

db.sessions

Answer

db.cpu.avg

Answer

db.bytes_sent

Question 7

A company is using Amazon Neptune and notices that some queries are slow. The DBA wants to identify which queries consume the most time. Which feature should be used?

Accepted Answer

Query profiler. Neptune's query profiler provides detailed information about query execution time. The slow query log only logs queries that exceed a threshold. The audit log is for security events. The performance insights is for RDS, not Neptune.

Answer

Database audit log

Answer

Slow query log

Answer

Performance Insights

Question 8

A database administrator notices that an Amazon RDS for MySQL instance is using 100% of its allocated storage. Which action should be taken first to prevent the instance from becoming inaccessible?

Accepted Answer

Modify the DB instance to increase allocated storage.. When an Amazon RDS for MySQL instance reaches 100% storage utilization, the most immediate action to prevent it from becoming inaccessible is to modify the DB instance to increase allocated storage. This adds storage capacity and allows normal operations to continue. Option B (snapshot and archive to S3) does not free up storage on the instance. Option C (deleting old binary logs) can free space but is not guaranteed to free enough and may not be a long-term solution; also, binary logs are needed for replication and point-in-time recovery. Option D (reboot) does not resolve the storage shortage.

Answer

Create a snapshot and archive it to Amazon S3.

Answer

Delete old binary logs to free up space.

Answer

Reboot the DB instance.

Question 9

A team is using Amazon RDS for Oracle with an option group that includes the Oracle Enterprise Manager (OEM) option. After modifying the option group to add a new option, the DB instance is stuck in the 'modifying' state for an extended period. What should the team do?

Accepted Answer

Reboot the DB instance to complete the modification.. Adding certain options may require a reboot. Option B is incorrect because the option group modification is likely valid; the issue is that it requires a reboot. Option C is incorrect because modifying the DB instance again would not help. Option D is incorrect because the DB instance is not in a failed state.

Answer

Contact AWS Support to force the modification.

Answer

Create a new DB instance with the desired options and migrate the data.

Answer

Modify the DB instance again to reset the state.

Question 10

A company is monitoring an Amazon Aurora MySQL DB cluster. They observe that the AuroraReplicaLagMaximum metric is consistently above 10 seconds. Which action would best reduce the replica lag?

Accepted Answer

Increase the instance size of the reader.. Increasing the instance size of the reader can improve its ability to apply changes faster. Option A is wrong because increasing the writer size may not help if the reader is the bottleneck. Option C is wrong because reducing transaction size helps but may not be feasible. Option D is wrong because Multi-AZ is always enabled for Aurora.

Answer

Increase the instance size of the writer.

Answer

Reduce the number of transactions per second.

Answer

Enable Multi-AZ on the cluster.

Question 11

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 12

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?

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 13

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 14

A company is using Amazon ElastiCache for Redis and notices that the cache hit ratio is low. The application is frequently reading data that is not in the cache. Which action would be most effective in improving the cache hit ratio?

Accepted Answer

Pre-warm the cache by loading frequently accessed data from the database.. Pre-warming the cache (option C) by loading frequently accessed data from the database into the ElastiCache cluster before it is requested increases the likelihood that subsequent reads will hit the cache. This directly improves the cache hit ratio. Increasing replicas (option A) does not add more cache capacity, it only provides read replicas for high availability. Decreasing TTL (option B) causes items to expire sooner, potentially reducing the hit ratio. Enabling Multi-AZ (option D) provides failover but does not affect hit ratio. Therefore, option C is the most effective action.

Answer

Increase the number of replicas in the replication group.

Answer

Decrease the TTL of cached items to ensure freshness.

Answer

Enable Multi-AZ for automatic failover.

Question 15

An Amazon RDS for MySQL instance is running out of storage. Which TWO actions can be taken to resolve this issue without downtime?

Accepted Answer

Enable storage auto scaling to automatically add storage.. Amazon RDS for MySQL supports modifying storage to increase allocated storage without downtime (option C). You can also enable storage auto scaling to automatically increase storage when thresholds are met (option A). Deleting unnecessary data (option B) might free space but is not a reliable proactive measure and could involve manual effort. Taking a snapshot and restoring to a larger instance (option D) requires downtime. Converting to Amazon Aurora (option E) is a migration process, not a direct fix for running out of storage.

Answer

Delete unnecessary data from the instance.

Answer

Take a snapshot and restore to a larger instance.

Answer

Convert the instance to Amazon Aurora.