DBS-C01 Practice Test 6 — 10 Questions

Question 1

A security engineer is designing a VPC with an RDS instance. The database must not be accessible from the internet, but EC2 instances in a private subnet must connect. Which security group configuration is MOST secure?

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

Accepted Answer

Set the RDS security group inbound rule to allow traffic from the EC2 security group on port 3306.. The most secure because it uses a security group reference instead of a CIDR block. By referencing the EC2 security group as the source in the RDS security group inbound rule, only instances associated with that specific security group can communicate with the database on port 3306. This approach adheres to the principle of least privilege and automatically scales as instances are added or removed from the EC2 security group, without needing to update CIDR ranges.

Answer

Set the RDS security group inbound rule to allow traffic from the VPC CIDR on port 3306.

Answer

Set the RDS security group inbound rule to allow traffic from 0.0.0.0/0 on port 3306.

Answer

Set the RDS security group inbound rule to allow traffic from the private subnet CIDR on port 3306.

Question 2

A company needs to migrate a SQL Server database to Amazon RDS for SQL Server. The database uses stored procedures with xp_cmdshell. What should the company do?

Accepted Answer

Rewrite the stored procedures to remove dependency on xp_cmdshell before migration.. Amazon RDS for SQL Server does not support the xp_cmdshell extended stored procedure because it allows execution of operating system commands, which violates the managed service model where AWS controls the host OS. The correct approach is to rewrite the stored procedures to remove dependency on xp_cmdshell before migration, using alternatives such as SQL Server Agent jobs, CLR integration, or external scripting via AWS Lambda or EC2.

Answer

Use RDS Custom for SQL Server to retain full control.

Answer

Enable xp_cmdshell in the RDS parameter group.

Answer

Disable xp_cmdshell in the stored procedures and migrate as-is.

Question 3

A company is migrating an on-premises MongoDB database to AWS. Which AWS database service is most compatible and requires minimal application changes?

Accepted Answer

Amazon DocumentDB (with MongoDB compatibility).. Amazon DocumentDB (with MongoDB compatibility) is the most compatible AWS database service for migrating an on-premises MongoDB database because it is purpose-built to emulate the MongoDB wire protocol and data model, allowing existing MongoDB drivers and tools to connect with minimal or no application code changes. This makes it the ideal choice for a lift-and-shift migration that preserves the document-oriented structure and query patterns of MongoDB.

Answer

Amazon DynamoDB.

Answer

Amazon Neptune.

Answer

Amazon RDS for MySQL.

Question 4

A company is experiencing slow query performance on an Amazon RDS for MySQL database. The DBA wants to identify the most time-consuming queries. Which TWO actions should the DBA take? (Choose two.)

Accepted Answer

Use Amazon RDS Performance Insights.. Amazon RDS Performance Insights (Option D) provides a database performance tuning and monitoring feature that visualizes database load and identifies the most time-consuming queries by breaking down wait events, SQL statements, and hosts. It directly helps the DBA pinpoint the specific queries causing performance degradation without additional configuration or overhead.

Answer

Enable the audit log.

Answer

Enable the general log and review it.

Answer

Use Amazon RDS Enhanced Monitoring.

Question 5

A company is migrating a 5 TB Oracle database to Amazon RDS for Oracle. The database has several large tables with LOB columns. The migration must have minimal downtime. Which approach should be taken?

Accepted Answer

Use AWS DMS with LOB support and ongoing replication from Oracle to RDS.. AWS DMS with LOB support and ongoing replication (change data capture, CDC) is the correct approach because it enables a near-zero downtime migration by continuously replicating changes from the source Oracle database to Amazon RDS for Oracle after an initial full load. DMS handles large LOB columns efficiently using its 'Full LOB mode' or 'Limited LOB mode' settings, which are critical for tables with LOB data. The combination of full load + CDC ensures minimal downtime, as the target remains synchronized until cutover.

Answer

Use Oracle GoldenGate to replicate data to RDS.

Answer

Use Oracle Data Pump to export the database and import into RDS.

Answer

Copy the database files to Amazon S3 and use the rdsadmin.rds_restore_from_s3 procedure.

Question 6

Which TWO factors should you consider when choosing between Amazon RDS and Amazon DynamoDB for a new application?

Accepted Answer

RDS requires a predefined schema, while DynamoDB is schema-less.. Amazon RDS (relational database service) requires a predefined schema with tables, columns, and data types before data can be inserted, enforcing ACID compliance and referential integrity. In contrast, Amazon DynamoDB is a NoSQL key-value and document database that is schema-less, allowing you to store items with varying attributes without upfront schema definition, which is ideal for agile development and unstructured data.

Answer

DynamoDB can only be accessed from within a VPC, while RDS can be public.

Answer

Only RDS supports Multi-AZ deployments for high availability.

Answer

Both services support encryption at rest and in transit.

Question 7

A company is migrating an on-premises MySQL database to Amazon RDS for MySQL. The database has a large table with frequent inserts and updates. To minimize downtime during migration, which AWS service should be used?

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) is the correct choice because it supports ongoing replication (change data capture, CDC) from an on-premises MySQL source to Amazon RDS for MySQL, allowing the source database to remain fully operational during the migration. This minimizes downtime by continuously applying inserts and updates from the source to the target until you perform the final cutover, which can be a brief pause of seconds to minutes.

Answer

Amazon RDS read replica

Answer

AWS Schema Conversion Tool (SCT)

Answer

AWS Glue

Question 8

A company runs a MySQL-compatible database on Amazon RDS for a mission-critical application. The database experiences high write latency due to frequent index updates. The team wants to redesign the database to reduce write amplification and improve insert performance. Which TWO design changes could help?

Accepted Answer

Use batch INSERT statements instead of single-row inserts. Batch INSERT statements reduce the overhead of per-row index updates by combining multiple rows into a single transaction. This minimizes the number of index tree traversals and log flushes, directly lowering write amplification and improving insert throughput in InnoDB.

Answer

Switch the storage engine from InnoDB to MyISAM

Answer

Upgrade to a larger RDS instance class

Answer

Normalize the database schema to reduce data redundancy

Question 9

A company is planning to migrate a 1 TB MySQL database from on-premises to Amazon RDS for MySQL. The migration must have minimal downtime and support ongoing replication. Which THREE steps should the company include in the migration plan? (Choose THREE.)

Accepted Answer

Set up an AWS Direct Connect or VPN connection between on-premises and AWS.. A stable, low-latency network connection (Direct Connect or VPN) is essential for AWS DMS to perform ongoing replication with minimal downtime. Without this, the replication can be interrupted by network issues, causing data loss or extended cutover windows.

Answer

Deploy an Amazon EC2 instance to act as a proxy for the DMS replication.

Answer

Install the AWS Schema Conversion Tool on the source server to convert the schema.

Question 10

A developer is trying to create a FULLTEXT index on a column in an RDS MySQL instance. The error log shows the index creation failed. What is the most likely cause?

Accepted Answer

The column 'description' has a length that exceeds the maximum allowed for FULLTEXT index.. In RDS MySQL, FULLTEXT indexes have a maximum column length limit of 1000 bytes for InnoDB and 1000 characters for MyISAM. If the 'description' column exceeds this limit, the index creation will fail. This is the most likely cause because the error log indicates a failure without other configuration issues.

Answer

The table size is too large for a FULLTEXT index to be created.

Answer

The table uses a character set that is not compatible with FULLTEXT indexes.

Answer

The InnoDB engine does not support FULLTEXT indexes.