DBS-C01 Deployment and Migration Practice Test 9 — 15 Questions

Question 1

Refer to the exhibit. A company is creating an IAM policy for a migration engineer who needs to perform a database migration from an on-premises SQL Server to Amazon RDS for SQL Server using AWS DMS. The policy is attached to the engineer's IAM user. Which additional permission is required for the engineer to create a DMS replication instance?

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

Accepted Answer

ec2:CreateInstance (or equivalent). To create a DMS replication instance, AWS DMS launches an Amazon EC2 instance in the customer's VPC to run the replication engine. The IAM user must have permission to call ec2:RunInstances (or the equivalent ec2:CreateInstance action) to provision this underlying compute resource. Without this EC2 permission, the DMS service cannot spin up the replication instance, and the migration engineer will receive an authorization error.

Answer

kms:CreateKey

Answer

dms:CreateEndpoint

Answer

s3:PutObject

Question 2

Refer to the exhibit. A company is migrating an on-premises database to Amazon RDS for MySQL. During a test migration, the DMS task fails with the error shown. The source database is 500 GB and the target RDS instance has 500 GB allocated storage. What should be done to resolve this error and complete the migration?

Accepted Answer

Enable storage autoscaling on the RDS instance. The error indicates that the target RDS instance ran out of storage during the migration. Enabling storage autoscaling allows RDS to automatically increase storage when free space is low, preventing the migration from failing due to insufficient disk space. This is the correct resolution because the source database is 500 GB and the target has exactly 500 GB allocated, leaving no room for temporary data or logs during the migration.

Answer

Increase the DB instance class to a larger size

Answer

Increase the DMS task's allocated storage

Answer

Reduce the size of the source database

Question 3

A company is migrating a 2 TB Oracle database from on-premises to Amazon RDS for Oracle using AWS DMS. The migration completes successfully, but the new RDS instance shows higher CPU utilization than the on-premises database for the same workload. Which action is MOST likely to reduce CPU utilization on RDS?

Accepted Answer

Increase the allocated storage to improve IOPS. Increasing allocated storage on Amazon RDS for Oracle directly improves the provisioned IOPS (if using Provisioned IOPS) or baseline IOPS (for gp2/gp3). Higher IOPS reduces I/O wait time, which is a common cause of high CPU utilization when the database is I/O-bound. Query optimization or instance resizing may also help, but increasing storage is a simple, low-risk action that often alleviates I/O-related CPU pressure. Option B is incorrect because Oracle Multitenant (CDB/PDB) architecture adds container management overhead and is not designed to reduce CPU utilization; also, converting an existing non-CDB RDS instance to CDB is not supported.

Answer

Disable automated backups to free resources

Answer

Enable Oracle Multitenant architecture

Answer

Change the RDS instance to a burstable class

Question 4

A company is migrating a PostgreSQL database to Amazon Aurora PostgreSQL. To minimize downtime, they plan to use the AWS DMS with change data capture (CDC). During the full load phase, DMS reports an error: 'Failed to add foreign key constraint'. What is the most likely cause?

Accepted Answer

Referential integrity violations in the source data. The error 'Failed to add foreign key constraint' during the full load phase of AWS DMS indicates that the source data contains referential integrity violations. DMS attempts to apply foreign key constraints on the target Aurora PostgreSQL after loading data, but if parent-child relationships are broken (e.g., orphan rows), the constraint creation fails. This is a common issue when migrating databases with existing data integrity problems, as DMS does not automatically validate or fix source data.

Answer

CDC is incompatible with foreign key constraints

Answer

The target table lacks a primary key

Answer

Data type mismatch between source and target

Question 5

A company is migrating a 1 TB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime and support ongoing replication. Which combination of AWS services should they use?

Accepted Answer

AWS SCT and AWS DMS. AWS DMS (Database Migration Service) can perform a full load of the 1 TB SQL Server database and then continuously replicate ongoing changes using change data capture (CDC) to minimize downtime. AWS SCT (Schema Conversion Tool) is used to assess and convert any incompatible schema objects (e.g., stored procedures, indexes) from the source SQL Server to the target RDS for SQL Server, ensuring a smooth migration. Together, they provide a complete solution for heterogeneous or homogeneous migration with minimal downtime and ongoing replication.

Answer

AWS S3 and AWS Glue

Answer

AWS DMS alone

Answer

Native SQL Server backup and restore to RDS

Question 6

A media company is migrating a 5 TB MongoDB database to Amazon DocumentDB. The migration must have minimal downtime. The source MongoDB uses sharding across 10 shards. Which migration strategy is MOST appropriate?

Accepted Answer

Use AWS DMS with MongoDB as source and DocumentDB as target, enabling CDC. AWS DMS with CDC (Change Data Capture) is the most appropriate strategy because it supports ongoing replication from a sharded MongoDB source to Amazon DocumentDB, enabling near-zero downtime migration. DMS can handle the 5 TB dataset and 10 shards by using the MongoDB oplog to capture changes after the initial full load, ensuring minimal interruption to the media company's operations.

Answer

Use native MongoDB replication to sync to DocumentDB

Answer

Export data to S3 and use AWS Glue to load into DocumentDB

Answer

Use mongoexport to export data and mongoimport to import into DocumentDB

Question 7

A company is migrating an on-premises MySQL database to Amazon RDS for MySQL. The database has a table with 100 million rows. During the migration using AWS DMS, the full load phase is taking too long. What change can speed up the full load?

Accepted Answer

Increase the number of DMS task mappings (parallel threads). Increasing the number of DMS task mappings (parallel threads) allows DMS to partition the source table and load multiple segments concurrently, significantly reducing the full load duration. By default, DMS uses a single thread per table; adding parallel threads leverages the source database's read capacity and the target RDS instance's write throughput more efficiently.

Answer

Reduce the target RDS instance storage to minimize write latency

Answer

Increase the size of the source on-premises database instance

Answer

Disable LOB columns in the task settings

Question 8

A company is migrating a 500 GB database from Amazon RDS for MySQL to Amazon Aurora MySQL. The migration must be completed with minimal downtime and no data loss. The RDS instance is Multi-AZ. Which approach should be used?

Accepted Answer

Create an Aurora MySQL read replica from the RDS MySQL instance, then promote it. Creating an Aurora MySQL read replica from the RDS MySQL instance uses the native MySQL binary log (binlog) replication to keep the Aurora cluster synchronized with minimal downtime. Once the replica lag reaches zero, you promote the Aurora cluster to make it the primary database, ensuring no data loss and a very short cutover window.

Answer

Use AWS DMS with ongoing replication from RDS to Aurora

Answer

Take a snapshot of the RDS instance and restore to Aurora

Answer

Set up native MySQL replication from the RDS Multi-AZ standby to Aurora

Question 9

A company is migrating a 3 TB PostgreSQL database to Amazon Aurora PostgreSQL. The migration must have minimal downtime. Which THREE steps should be taken?

Accepted Answer

Use AWS DMS with ongoing replication from the source PostgreSQL database. Option B is correct because AWS Database Migration Service (DMS) with ongoing (change data capture) replication keeps the target Aurora PostgreSQL continuously synchronized with the source after the initial full load, allowing the cutover to happen during a short window and thus achieving minimal downtime. Option D is correct because creating an Aurora PostgreSQL read replica lets you offload read traffic from the primary during the migration, reducing contention and preserving performance for the migration workload. Option E is correct because increasing the Aurora instance class provides more CPU, memory, and I/O capacity to handle the heavy load of the initial data load and replication, which helps keep the migration fast and downtime low. Option A is not appropriate because disabling autovacuum can lead to table bloat and performance degradation rather than improving migration reliability. Option C is not appropriate because AWS Snowball Edge is an offline physical transfer device, which is unnecessary and would introduce significant delay for a 3 TB database migration that requires minimal downtime.

Answer

Disable autovacuum on the Aurora cluster to improve migration performance

Answer

Use AWS Snowball Edge to transfer the data offline

Question 10

A company is planning to migrate a 1 TB SQL Server database to Amazon RDS for SQL Server. Which TWO factors should be considered when choosing the migration approach?

Accepted Answer

The need to modify the database schema for compatibility. When migrating a SQL Server database to Amazon RDS, certain features like full-text search, CLR assemblies, or deprecated data types may not be supported or require schema modifications. RDS for SQL Server does not support all SQL Server features (e.g., FileStream, Service Broker, or cross-database references), so the schema must be reviewed and potentially altered to ensure compatibility before migration.

Answer

The number of concurrent users accessing the database

Answer

Whether the database uses SQL Server Agent jobs

Answer

The version of the source SQL Server instance

Question 11

A company is deploying a new multi-AZ application that requires a relational database. The database must be highly available and must automatically failover to a standby in another Availability Zone within minutes. The database size is 500 GB and the workload is read-heavy. Which AWS RDS configuration meets these requirements?

Accepted Answer

Deploy Amazon RDS for MySQL with Multi-AZ and a read replica in a different AZ. Deploying Amazon RDS for MySQL with Multi-AZ provides automatic failover to a standby in a different Availability Zone within minutes, meeting the high availability requirement. Adding a read replica in a different AZ offloads read traffic, which is ideal for the read-heavy workload, without affecting the primary database's performance.

Answer

Deploy Amazon Aurora with Multi-AZ

Answer

Deploy Amazon RDS for PostgreSQL with a cross-Region read replica

Answer

Deploy Amazon RDS for Oracle with RDS Proxy

Question 12

A developer is deploying an application that uses Amazon DynamoDB as its database. The application experiences sudden spikes in traffic. Which DynamoDB feature should the developer use to handle the spikes without manual intervention?

Accepted Answer

DynamoDB auto scaling. DynamoDB auto scaling (option C) is the correct choice because it automatically adjusts the provisioned read and write capacity based on actual traffic patterns using the AWS Application Auto Scaling service. This allows the application to handle sudden spikes in traffic without manual intervention by increasing capacity when utilization rises and decreasing it when traffic subsides, all while maintaining a target utilization percentage.

Answer

DynamoDB Accelerator (DAX)

Answer

DynamoDB on-demand capacity mode

Answer

DynamoDB global tables

Question 13

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 1 TB and has a large number of stored procedures and triggers. The migration must minimize application changes. Which migration approach should be used?

Accepted Answer

Use AWS Database Migration Service (AWS DMS) with full load and ongoing replication. AWS DMS with full load and ongoing replication minimizes application changes by supporting heterogeneous migrations with minimal downtime, and it can handle stored procedures and triggers by replicating data changes in near real-time without requiring schema conversion. AWS DMS directly supports Oracle as a source and Amazon RDS for Oracle as a target, preserving the existing schema and procedural logic, which avoids the need for application rewrites.

Answer

Use AWS Schema Conversion Tool (AWS SCT) to convert the schema and AWS DMS for data migration

Answer

Use Oracle Data Pump (expdp/impdp) to export and import the database

Answer

Use AWS S3 to store the data and AWS Glue to transform and load into RDS

Question 14

A company is deploying a new web application on AWS. The application uses Amazon RDS for MySQL with a Multi-AZ deployment. The application team wants to reduce latency for read-heavy workloads. Which action should be taken?

Accepted Answer

Add a read replica in the same Region. Adding a read replica in the same Region offloads read-heavy workloads from the primary RDS instance, reducing latency for read queries because replicas serve read traffic directly. Amazon RDS for MySQL read replicas use asynchronous replication and can be promoted to a primary instance if needed, making this the most effective and cost-efficient solution for read scaling.

Answer

Enable Multi-AZ on the existing RDS instance

Answer

Increase the instance size of the primary RDS instance

Answer

Switch from RDS to Amazon DynamoDB with DAX

Question 15

A company needs to migrate a 5 TB Oracle database to Amazon Aurora PostgreSQL. The company has a limited maintenance window and requires the migration to be completed within a few hours. Which approach should be used?

Accepted Answer

Use AWS Database Migration Service (AWS DMS) to migrate the data. AWS Database Migration Service (AWS DMS) can migrate data directly from Oracle to Aurora PostgreSQL, including both schema conversion and data migration. DMS supports automatic schema conversion for many source/target pairs, including Oracle to PostgreSQL, so a separate schema conversion tool like AWS SCT is not required. With parallel load and change data capture (CDC), DMS can complete a 5 TB migration within a few hours while minimizing downtime.

Answer

Use AWS Schema Conversion Tool (AWS SCT) to convert the schema and AWS DMS for data migration

Answer

Use pg_dump to export the Oracle database and pg_restore to import into Aurora

Answer

Use AWS S3 to store the data and AWS Glue to transform and load into Aurora