DBS-C01 Deployment and Migration Practice Test 1 — 15 Questions

Question 1

A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 2 TB in size and has a high write workload. The company needs to minimize downtime during the migration. Which AWS service or feature should the company use to achieve this?

Accepted Answer

Use AWS Database Migration Service (AWS DMS) with ongoing replication.. AWS DMS with ongoing replication (change data capture, CDC) is the correct choice because it allows continuous synchronization of the source PostgreSQL database with the target RDS for PostgreSQL instance after an initial full load. This minimizes downtime by enabling the target to stay up-to-date with changes until the cutover, which is critical for a 2 TB database with a high write workload.

Answer

Use pg_dump and pg_restore to export and import the database.

Answer

Use the AWS Schema Conversion Tool (AWS SCT) to convert the schema and migrate data.

Answer

Use AWS DataSync to replicate the database files.

Question 2

A company wants to migrate its on-premises Oracle database to Amazon Aurora PostgreSQL. The company needs to automatically convert the Oracle schema to PostgreSQL-compatible format. Which AWS service should the company use?

Accepted Answer

AWS Schema Conversion Tool (AWS SCT). AWS Schema Conversion Tool (AWS SCT) is designed specifically to convert database schemas from one engine to another, including Oracle to Amazon Aurora PostgreSQL. It automatically translates Oracle DDL (tables, indexes, stored procedures, functions, etc.) into PostgreSQL-compatible format, handling data type mappings, PL/SQL to PL/pgSQL conversion, and other schema-level transformations. AWS DMS handles data migration, not schema conversion, making SCT the correct choice for this requirement.

Answer

AWS Database Migration Service (AWS DMS) with the Oracle native dump and load option

Answer

AWS Server Migration Service (AWS SMS)

Answer

AWS Database Migration Service (AWS DMS)

Question 3

A company is using AWS Database Migration Service (AWS DMS) to migrate a 5 TB MySQL database to Amazon RDS for MySQL. The migration is taking longer than expected. The company notices that the source database has a high volume of write operations. Which configuration change would MOST likely improve the migration performance?

Accepted Answer

Increase the number of parallel threads in the DMS task settings.. Increasing the number of parallel threads in the DMS task settings allows AWS DMS to process multiple table partitions or row changes concurrently, which directly addresses the bottleneck caused by a high volume of write operations on the source. By default, DMS uses a single thread per table, but when the source is under heavy write load, parallel threads can capture and apply changes more efficiently, reducing the overall migration time.

Answer

Enable Multi-AZ on the target RDS instance.

Answer

Use a smaller instance class for the replication instance to reduce cost.

Answer

Set the LOB mode to 'Full LOB mode'.

Question 4

A company is migrating an on-premises Microsoft SQL Server database to Amazon RDS for SQL Server. The database uses SQL Server Agent jobs for ETL processes. After migration, the company needs to continue running these jobs. What is the MOST efficient way to manage these jobs in the AWS cloud?

Accepted Answer

Recreate the jobs as AWS Lambda functions and trigger them with Amazon CloudWatch Events.. AWS Lambda functions triggered by Amazon CloudWatch Events (now Amazon EventBridge) provide a serverless, fully managed alternative to SQL Server Agent jobs. This approach eliminates the need to manage any compute infrastructure, as Lambda handles the execution of ETL logic directly against the RDS for SQL Server instance. It is the most efficient because it requires no additional servers, reduces operational overhead, and integrates natively with AWS monitoring and scheduling services.

Answer

Install SQL Server Agent on an Amazon EC2 instance and connect to RDS.

Answer

Use the AWS Schema Conversion Tool (AWS SCT) to convert the jobs to PostgreSQL functions.

Answer

Use AWS Database Migration Service (AWS DMS) tasks to replicate the jobs.

Question 5

A company needs to migrate a 100 GB MongoDB database to Amazon DocumentDB (with MongoDB compatibility). The migration must have minimal impact on the source database performance. Which approach should the company take?

Accepted Answer

Use AWS Database Migration Service (AWS DMS) with ongoing replication from the MongoDB source.. AWS DMS with ongoing replication is the correct approach because it supports continuous change data capture (CDC) from MongoDB, enabling a live migration with minimal performance impact on the source. DMS reads the MongoDB oplog to capture changes without locking the database, which is critical for a 100 GB production database. This allows the target DocumentDB to stay synchronized until cutover, reducing downtime and avoiding the need for a full export/import that would strain the source.

Answer

Use AWS DataSync to transfer the MongoDB data files.

Answer

Set up a MongoDB replica set on Amazon EC2 and promote it to primary, then migrate to DocumentDB.

Answer

Use mongodump to export the data and mongorestore to import into DocumentDB.

Question 6

A company is migrating a 3 TB on-premises Oracle database to Amazon Aurora PostgreSQL using AWS DMS. The migration task is failing with an error indicating insufficient memory. Which TWO actions should the company take to resolve this issue? (Choose TWO.)

Accepted Answer

Increase the instance class of the DMS replication instance.. Option C is correct because the 'insufficient memory' error during an AWS DMS migration indicates that the replication instance lacks the memory required to handle the data volume, transformation rules, or cache for large transactions. Increasing the instance class (e.g., from dms.c5.large to dms.c5.2xlarge) provides more memory and CPU, directly resolving the resource constraint.

Answer

Change the target database engine to Amazon RDS for MySQL.

Answer

Disable Multi-AZ on the DMS replication instance.

Answer

Use a smaller instance class for the DMS replication instance.

Question 7

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.. Option A is correct because 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 8

A team is setting up a DMS migration task. The IAM policy above is attached to the DMS replication instance's IAM role. The team is unable to modify the target RDS instance's maintenance window during the migration. Which additional permission is missing?

Accepted Answer

Add 'rds:ModifyDBInstance' permission for the source RDS instance.. The correct answer is A because modifying the target RDS instance's maintenance window requires the `rds:ModifyDBInstance` permission. The DMS replication instance's IAM role must have this permission for the target RDS instance to allow the migration task to adjust the maintenance window, which is necessary to prevent conflicts during ongoing replication. Without this permission, the DMS task cannot alter the maintenance window, even if the IAM role has other RDS permissions.

Answer

Add 'rds:ModifyOptionGroup' permission for the target RDS instance.

Answer

Add 'dms:ModifyReplicationInstance' permission for the DMS replication instance.

Answer

Add 'ec2:DescribeVpcs' permission to the policy.

Question 9

A team is migrating an on-premises database to Amazon RDS using AWS DMS. After the full load completed, the task stopped. The team needs to perform ongoing replication to minimize downtime. What change should the team make to the DMS task?

Accepted Answer

Modify the replication task to change the migration type to 'full-load-and-cdc'.. After a full load completes and the task stops, the team needs to enable ongoing replication to capture and apply changes made to the source database during the migration window. Modifying the DMS task to use the 'full-load-and-cdc' migration type allows the task to perform the initial full load and then seamlessly transition to Change Data Capture (CDC) to replicate incremental changes, minimizing downtime. This is the correct approach because DMS supports switching a completed full-load task to include CDC without re-running the full load.

Answer

Restart the replication task with the same settings.

Answer

Create a new replication instance and start a new full-load task.

Answer

Use AWS Schema Conversion Tool to convert the schema again.

Question 10

A company is migrating a 500 GB on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The migration must have minimal downtime and support ongoing replication after the initial load. Which AWS service should be used?

Accepted Answer

AWS Database Migration Service (DMS) with ongoing replication. AWS Database Migration Service (DMS) with ongoing replication (change data capture, CDC) is required because the scenario demands minimal downtime and continuous synchronization after the initial 500 GB load. DMS uses transaction logs (e.g., PostgreSQL WAL) to capture and apply ongoing changes, enabling a near-zero-duration cutover. Full load only (Option B) would cause downtime during the final sync and cannot support ongoing replication.

Answer

AWS Schema Conversion Tool (SCT)

Answer

AWS Database Migration Service (DMS) with full load only

Answer

AWS Glue

Question 11

A company is migrating a self-managed Oracle database to Amazon Aurora PostgreSQL using AWS DMS. The source database has a large number of tables with foreign key constraints. During the full load phase, some tables fail to load due to foreign key violations. What is the most efficient way to resolve this?

Accepted Answer

Disable foreign key constraints on the target before migration and re-enable after. Option C is correct because disabling foreign key constraints on the target Aurora PostgreSQL database before the migration allows DMS to load tables in any order without violating referential integrity. After the full load completes, re-enabling the constraints ensures data consistency. This approach is the most efficient as it avoids complex dependency ordering and reduces migration failures.

Answer

Increase the DMS task memory and parallel load threads

Answer

Use the table preparation mode 'Do nothing' and load tables in dependency order

Answer

Pre-create all target tables with the same constraints and use 'Truncate' mode

Question 12

A company wants to migrate an on-premises MySQL database to Amazon RDS for MySQL with minimal downtime. They plan to use AWS DMS. Which source database configuration is required to enable ongoing replication (CDC)?

Accepted Answer

Enable binary logging (binlog) on the source database. AWS DMS requires binary logging (binlog) enabled on the source MySQL database to capture ongoing changes for continuous replication (CDC). The binlog records all data modifications (INSERT, UPDATE, DELETE) in a sequential log, which DMS reads to apply those changes to the target RDS instance with minimal downtime. Without binlog enabled, DMS can only perform a full load migration and cannot support ongoing replication.

Answer

Set auto_increment_increment to 1

Answer

Enable the slow query log

Answer

Enable the query cache

Question 13

A company is migrating a 2 TB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime and are using AWS DMS with CDC. The migration is taking longer than expected during the full load phase. Which change would most likely improve the full load performance?

Accepted Answer

Increase the number of parallel load tasks in the DMS task settings. Increasing the number of parallel load tasks in the DMS task settings allows the full load to be split into multiple concurrent threads, each handling a subset of tables or partitions. This directly improves throughput by utilizing more of the available source and target resources, which is the most effective way to accelerate a slow full load phase when using AWS DMS with CDC.

Answer

Disable CDC to focus on full load only

Answer

Use AWS Schema Conversion Tool to optimize schema

Answer

Use a larger RDS instance class for the target

Question 14

A company is migrating an on-premises MongoDB database to Amazon DocumentDB (with MongoDB compatibility). They want to validate that the data is consistent after migration. Which tool should they use?

Accepted Answer

AWS DMS data validation. AWS DMS data validation is the correct tool because it provides built-in, row-level checksum-based validation that compares source and target data after a full load or ongoing replication. For DocumentDB migrations, DMS can compute and compare checksums on the fly, ensuring consistency without requiring manual scripting or external tools. This is the recommended AWS approach for validating data integrity during and after a migration to DocumentDB.

Answer

mongoexport and mongoimport

Answer

dbHash command on both databases

Answer

DocumentDB native consistency check tool

Question 15

A company is migrating a 1 TB Oracle database to Amazon Aurora PostgreSQL using AWS DMS. They need to ensure minimal downtime and data consistency. Which TWO actions should the company take?

Accepted Answer

Enable change data capture (CDC) on the source Oracle database. Option B is correct because enabling Change Data Capture (CDC) on the source Oracle database allows AWS DMS to capture ongoing changes after the full load, enabling a near-zero downtime migration by continuously replicating transactions to the target Aurora PostgreSQL. Option C is correct because enabling data validation on the DMS task ensures that the data migrated is consistent between the source and target, verifying that no data loss or corruption occurred during the migration process.

Answer

Increase the target Aurora storage to 2 TB to avoid storage issues

Answer

Disable foreign key constraints on the target during migration

Answer

Use AWS Schema Conversion Tool to convert the schema