DBS-C01 Management and Operations Practice Test 3 — 15 Questions

Question 1

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 2

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 3

A company is using Amazon DynamoDB and needs to export data to Amazon S3 for analysis. Which AWS service can perform this export without writing custom code?

Accepted Answer

AWS Glue. AWS Glue provides a built-in DynamoDB-to-S3 export feature that requires no custom code. You can create a Glue job using the 'Export DynamoDB table to S3' blueprint, which automatically handles schema inference, data conversion, and partitioning. This is the only option that directly supports the export without writing any code.

Answer

AWS Data Pipeline

Answer

Amazon EMR

Answer

DynamoDB Console

Question 4

Which TWO actions can help reduce the recovery time objective (RTO) for an Amazon RDS for PostgreSQL DB instance in the event of a failure? (Choose 2.)

Accepted Answer

Enable Multi-AZ deployment.. Options B and C are correct because Multi-AZ provides automatic failover, and automated backups with point-in-time recovery enable fast restore. Option A is wrong because Read replicas are for read scaling, not failover. Option D is wrong because manual snapshots are not automated and slower. Option E is wrong because increasing instance size does not reduce RTO.

Answer

Increase the DB instance class size.

Answer

Create a read replica in a different Availability Zone.

Answer

Take manual snapshots every hour.

Question 5

Which THREE factors should be considered when planning a cross-Region disaster recovery strategy for an Amazon Aurora MySQL DB cluster? (Choose 3.)

Accepted Answer

Network latency between source and target Regions.. Options A, C, and E are correct because RPO determines acceptable data loss, network latency affects replication lag, and storage costs vary by region. Option B is wrong because IOPS are not a direct DR consideration. Option D is wrong because failover priority is for local replication, not cross-Region.

Answer

Provisioned IOPS for the primary cluster.

Answer

Failover priority of reader instances.

Question 6

Which TWO methods can be used to encrypt an existing unencrypted Amazon RDS for Oracle DB instance? (Choose 2.)

Accepted Answer

Create a snapshot of the DB instance, copy the snapshot with encryption enabled, and restore the DB instance from the encrypted snapshot.. Options A and D are correct because you can create a snapshot, copy it with encryption, and restore; or use DMS to migrate to an encrypted target. Option B is wrong because you cannot directly enable encryption on an existing instance. Option C is wrong because enabling encryption on a replica requires the source to be encrypted. Option E is wrong because the console does not allow direct modification.

Answer

Use the AWS Management Console to toggle encryption on the DB instance.

Answer

Modify the DB instance and enable encryption in the configuration.

Answer

Create a read replica with encryption enabled.

Question 7

A DBA runs the above AWS CLI command. The DB instance is an Amazon RDS for MySQL instance. The DBA needs to connect to the database from an EC2 instance in the same VPC but cannot connect. Which action should be taken first?

Accepted Answer

Check the inbound rules of the security group for port 3306.. Option D is correct because the VPC security group (sg-0123456789abcdef0) must allow inbound traffic on port 3306 (MySQL) from the EC2 instance's security group. Option A is wrong because the endpoint is correct. Option B is wrong because the instance is available. Option C is wrong because encryption does not affect connectivity.

Answer

Verify that the DB instance endpoint resolves correctly from the EC2 instance.

Answer

Enable encryption on the DB instance.

Answer

Check the DB instance status in the output.

Question 8

A DBA runs the IAM policy simulation above. The DBA can describe the DB instance but cannot modify it. What is the most likely cause?

Accepted Answer

An IAM policy explicitly denies the rds:ModifyDBInstance action.. Option A is correct because an explicit deny overrides any allow. Option B is wrong because the simulation does not check network conditions. Option C is wrong because the DBA can describe, so there is an allow for that action. Option D is wrong because the resource ARN is correct for the DB instance.

Answer

The resource ARN in the simulation is incorrect.

Answer

The DBA's IAM policy does not include an allow for rds:ModifyDBInstance.

Answer

The DBA is not within the VPC where the DB instance resides.

Question 9

A DBA sees the above error log entries for an Amazon RDS for PostgreSQL DB instance. What is the most likely cause?

Accepted Answer

The user 'myuser@mycompany.com' is using an incorrect password.. Option A is correct because the error message indicates authentication failure, likely due to an incorrect password. Option B is wrong because the error says authentication failure, not about the user's existence. Option C is wrong because resource limits cause different errors. Option D is wrong because network issues cause timeout errors, not authentication failures.

Answer

There is a network connectivity issue between the client and the database.

Answer

The database has reached its maximum number of connections.

Answer

The user 'myuser@mycompany.com' does not exist in the database.

Question 10

A company's Amazon RDS for MySQL instance is experiencing high CPU utilization. The company's application is write-heavy. The database administrator wants to reduce the load on the primary instance. Which solution is MOST effective?

Accepted Answer

Use Amazon ElastiCache to cache frequent writes.. Option C is correct because creating a read replica offloads read queries, not writes. Option D is correct because Multi-AZ with standby provides high availability but does not offload reads. Option A is incorrect because increasing instance size addresses symptoms temporarily. Option B is incorrect because adding a read replica does not reduce write load.

Answer

Increase the instance size of the RDS instance.

Answer

Create a read replica and redirect read traffic to it.

Answer

Enable Multi-AZ deployment to distribute writes.

Question 11

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 12

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 13

A team is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The database is 2 TB and has a 6-hour maintenance window. Which AWS service should the team use to minimize downtime?

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS DMS is the correct choice because it can perform a live migration from Oracle to Aurora PostgreSQL with minimal downtime using ongoing replication (change data capture). It supports heterogeneous migrations, automatically converting the source schema and data types, and can handle a 2 TB database within the 6-hour maintenance window by using multiple parallel tasks and large instance types.

Answer

Amazon S3 Transfer Acceleration

Answer

AWS Snowball Edge

Answer

Amazon EC2 with Oracle installed

Question 14

A company uses Amazon RDS for MySQL with Multi-AZ deployment. The primary instance fails and the database administrator notices that the failover did not happen automatically. What is the MOST likely cause?

Accepted Answer

The DB instance is configured as a read replica.. Option A is incorrect because Multi-AZ handles failover automatically. Option B is correct because read replicas do not support automatic failover. Option C is incorrect because it would not prevent failover. Option D is incorrect because monitoring does not affect failover.

Answer

The DB instance is in a public subnet.

Answer

Enhanced Monitoring is disabled.

Answer

The standby instance is in a different VPC.

Question 15

A company wants to encrypt an existing unencrypted Amazon RDS for SQL Server instance. What is the MOST efficient way to achieve this?

Accepted Answer

Create a snapshot of the DB instance and copy it with encryption enabled. Restore the snapshot to a new encrypted instance.. Option A is correct because creating a snapshot and copying with encryption is the standard method. Option B is incorrect because you cannot enable encryption on existing instance. Option C is incorrect because it is not supported. Option D is incorrect because restoring snapshot to encrypted instance works but the process is snapshot copy.

Answer

Create a read replica with encryption enabled.

Answer

Modify the DB instance to enable encryption.

Answer

Use AWS DMS to migrate data to a new encrypted instance.