DBS-C01 Practice Test 47 — 15 Questions

Question 1

A database specialist is troubleshooting a performance issue on an Amazon RDS for MySQL DB instance. The CPU utilization is consistently above 90%, but the IOPS and memory metrics are well within limits. Which tool should the specialist use to identify the root cause?

Accepted Answer

Use Amazon RDS Performance Insights to identify the top SQL queries by CPU usage.. Option A is correct. Performance Insights can show the queries that are consuming the most CPU. Option B is wrong because Enhanced Monitoring is for OS-level metrics, not per-query CPU usage. Option C is wrong because RDS Events are for operational events. Option D is wrong because CloudTrail is for API calls.

Answer

Enable AWS CloudTrail to log database queries.

Answer

Use Amazon RDS Enhanced Monitoring to view OS-level metrics.

Answer

Check RDS events in the AWS Management Console.

Question 2

A company wants to automate the creation of a new Amazon RDS for SQL Server instance with specific configurations, including VPC, subnet, and security group settings. Which AWS service should be used to deploy this infrastructure as code?

Accepted Answer

AWS CloudFormation. AWS CloudFormation allows you to define infrastructure as code and automate resource creation.

Answer

AWS CodeDeploy

Answer

AWS Elastic Beanstalk

Answer

AWS OpsWorks

Question 3

A company is running Amazon Redshift for data warehousing. The data warehouse is used for complex analytical queries. Recently, query performance has degraded due to data skew. Which steps should be taken to address this issue?

Accepted Answer

Re-evaluate the distribution style of the tables.. Option B is correct because choosing an appropriate distribution style (e.g., KEY or EVEN) can reduce data skew and improve performance. Option A is wrong while sorting can help query performance, it does not directly address skew. Option C is wrong because adding more nodes may not resolve skew. Option D is wrong because compression reduces storage, not skew.

Answer

Apply sort keys on the skewed columns.

Answer

Apply compression on the skewed columns.

Answer

Increase the number of nodes in the cluster.

Question 4

A company is using Amazon DynamoDB with on-demand capacity. The application performs many small writes that are throttled frequently. The company wants to minimize costs while reducing throttling. What should the company do?

Accepted Answer

Switch to provisioned capacity with auto scaling.. Option A is incorrect because on-demand already scales. Option B is correct because DynamoDB Accelerator (DAX) reduces read/write load. Option C is incorrect because provisioned with auto scaling can be cost-effective. Option D is incorrect because batch writes may not fit small writes.

Answer

Increase the write capacity units manually.

Answer

Use DynamoDB Accelerator (DAX) to cache writes.

Answer

Use batch writes to combine small writes.

Question 5

A company wants to monitor the performance of an Amazon RDS for MySQL instance. Which TWO metrics are available in Amazon CloudWatch by default? (Choose 2.)

Accepted Answer

CPUUtilization. Option A is correct because CPUUtilization is a default metric. Option B is correct because DatabaseConnections is a default metric. Option C is incorrect because it is a metric for DynamoDB. Option D is incorrect because it is for Redshift. Option E is incorrect because it is not a default metric.

Answer

FreeableMemory

Answer

QueryThroughput

Answer

ReadThrottleEvents

Question 6

A database specialist is managing an Amazon RDS for Oracle DB instance. The instance has a large amount of data and the specialist needs to migrate it to a new instance in a different AWS Region. Which method would minimize downtime and be the most efficient?

Accepted Answer

Use AWS Database Migration Service (DMS) with ongoing replication to migrate to the target instance.. Option C is correct. AWS Database Migration Service (DMS) with ongoing replication minimizes downtime and supports cross-region migration. Option A is wrong because exporting to S3 and importing is time-consuming and does not support ongoing replication. Option B is wrong because cross-region read replicas are not available for Oracle. Option D is wrong because RMAN backups are not integrated with AWS for cross-region migration.

Answer

Export the database to Amazon S3 using Oracle Data Pump, then import into the new instance.

Answer

Create a cross-region read replica and promote it.

Answer

Take a full backup using Oracle RMAN, copy the backup files to the target region, and restore.

Question 7

A SysOps administrator is tasked with monitoring the free storage space on all Amazon RDS DB instances. Which AWS service should be used to set up an alarm that sends an email notification when free storage space falls below a threshold?

Accepted Answer

Amazon CloudWatch with an alarm on the FreeStorageSpace metric and an SNS topic.. Option A is correct because Amazon CloudWatch can monitor RDS metrics such as 'FreeStorageSpace' and trigger an alarm that sends a notification via Amazon SNS. Option B is incorrect because AWS CloudTrail is for auditing API calls. Option C is incorrect because AWS Config tracks resource configuration changes. Option D is incorrect because Amazon Inspector is for security assessments.

Answer

AWS CloudTrail to monitor storage events.

Answer

AWS Config to track storage configuration changes.

Answer

Amazon Inspector to check for storage vulnerabilities.

Question 8

A company is migrating its on-premises PostgreSQL database to Amazon Aurora PostgreSQL. The migration must have minimal downtime. Which THREE steps should be taken as part of the migration plan? (Select THREE.)

Accepted Answer

Perform a test migration to validate the process.. Options A, B, and C are correct. Setting up replication from the on-premises database to Aurora using AWS DMS with ongoing replication allows the target to stay up-to-date with minimal downtime. Performing a test migration ensures the process works. After the cutover, the application connection string must be updated. Option D is incorrect because disabling automated backups is not recommended; backups are essential. Option E is incorrect because enabling Multi-AZ is for high availability, not a migration step.

Answer

Enable Multi-AZ on the Aurora cluster before migration.

Answer

Disable automated backups on the Aurora cluster to improve performance.

Question 9

A company is running a production Amazon RDS for MySQL Multi-AZ DB instance. The database administrator needs to perform a minor version upgrade with minimal downtime. Which TWO actions should be taken? (Choose TWO.)

Accepted Answer

Modify the DB instance to enable automatic minor version upgrade.. Enabling automatic minor version upgrade allows the upgrade to occur during the maintenance window with minimal downtime. Applying the upgrade immediately during the maintenance window also minimizes impact. Stopping the instance causes downtime. Modifying the DB instance to single-AZ increases downtime risk. Creating a read replica does not help upgrade the primary.

Answer

Create a read replica, upgrade the replica, and promote it.

Answer

Modify the DB instance to be a Single-AZ deployment to simplify the upgrade.

Answer

Stop the DB instance before applying the upgrade.

Question 10

A company is using Amazon ElastiCache for Redis as a caching layer for a high-traffic web application. The cache hit ratio has dropped from 95% to 70% after a recent deployment that changed the cache key structure. The application team wants to improve the hit ratio without increasing the cache memory. Which action should they take?

Accepted Answer

Implement a consistent hashing algorithm for key distribution.. Option B is correct because using a consistent hashing algorithm ensures that keys are evenly distributed across nodes, reducing evictions and improving hit ratio. Option A is wrong because increasing TTL may cause stale data but does not directly improve hit ratio. Option C is wrong because Cluster Mode Off would limit scalability but not necessarily improve hit ratio. Option D is wrong because random TTLs can lead to premature evictions and reduce hit ratio.

Answer

Disable Cluster Mode and use a single node.

Answer

Increase the TTL (time-to-live) for all cache keys.

Answer

Use random TTLs to spread out expiration times.

Question 11

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a 100 Mbps internet connection. The migration must be completed within 3 days with minimal downtime. Which approach is MOST suitable?

Accepted Answer

Use AWS Database Migration Service (DMS) with a full load from an AWS Snowball device, then ongoing replication.. Option A is correct because AWS DMS can perform a live migration with minimal downtime, and using an AWS Snowball for the initial load reduces the time over the slow internet connection. Option B is wrong because uploading over the internet would take too long. Option C is wrong because restoring from an on-premises backup over the internet is also slow. Option D is wrong because a VPN does not solve the bandwidth limitation.

Answer

Export the database as a dump file, upload to S3, and restore to RDS.

Answer

Use AWS DMS with full load over the internet, then ongoing replication.

Answer

Create a VPN connection to AWS and use Oracle Data Pump over the VPN.

Question 12

A company has an Amazon RDS for SQL Server DB instance with Multi-AZ deployment. During a recent failover test, the application experienced a longer downtime than expected. The application uses a single connection string. What change should be made to reduce failover downtime?

Accepted Answer

Use a custom DNS CNAME record pointing to the RDS endpoint.. Option C is correct because using a CNAME that points to the RDS endpoint ensures that after failover, the DNS record updates automatically, reducing downtime. Option A is wrong because setting TTL too low may cause DNS propagation delays. Option B is wrong because the RDS endpoint already handles failover. Option D is wrong because Connection pooling does not reduce failover time.

Answer

Implement connection pooling in the application.

Answer

Set the DNS TTL to a higher value.

Answer

Configure the application to use the RDS instance ID instead of endpoint.

Question 13

A database administrator needs to monitor the number of database connections to an Amazon RDS for PostgreSQL instance. Which Amazon CloudWatch metric should the administrator use?

Accepted Answer

DatabaseConnections. Option A is correct because DatabaseConnections is the standard metric. Option B is incorrect because it is not a CloudWatch metric. Option C is incorrect because it is a custom metric, not standard. Option D is incorrect because it is a dimension, not a metric.

Answer

ActiveConnections

Answer

ConnectionsCount

Answer

DBInstanceIdentifier

Question 14

A database administrator runs the above CLI command. The DB instance has pending modifications. Which modification will take effect immediately without requiring a reboot?

Accepted Answer

BackupRetentionPeriod. Option C is correct because changing the backup retention period takes effect immediately without reboot. Option A is incorrect because it requires a reboot. Option B is incorrect because it requires a reboot. Option D is incorrect because it requires a reboot.

Answer

DBInstanceClass

Answer

MasterUserPassword

Answer

AllocatedStorage

Question 15

A company is using Amazon ElastiCache for Redis as a caching layer in front of an Amazon Aurora MySQL database. The application is experiencing higher latency than expected. Which database design pattern should the specialist recommend to improve read performance?

Accepted Answer

Use Aurora Replicas to offload read traffic from the primary instance.. Option B is correct. Adding Aurora Replicas to distribute read traffic improves read performance and reduces load on the primary. Option A is wrong because DAX is for DynamoDB, not Aurora. Option C is wrong because increasing cache size may not help if cache misses are not the issue. Option D is wrong because read replicas in ElastiCache are already used; the issue is the database.

Answer

Increase the ElastiCache cluster size to accommodate more data.

Answer

Enable Multi-AZ on the ElastiCache cluster and use read replicas.

Answer

Implement Amazon DynamoDB Accelerator (DAX) in front of Aurora.