DBS-C01 Deployment and Migration Practice Test 8 — 15 Questions

Question 1

A company is migrating a 4 TB Oracle database to Amazon Aurora PostgreSQL using AWS DMS. The migration completes successfully but the application experiences high latency on the Aurora cluster. The DMS task used LOB mode 'full LOB mode'. What is the most likely cause of the latency?

Accepted Answer

Full LOB mode caused large LOBs to be stored in the Aurora cluster, leading to increased I/O. Option A is correct because full LOB mode stores LOBs inline, increasing storage and I/O. Option B is wrong because CDC is not the cause. Option C is wrong because DMS does not use cross-region replication. Option D is wrong because parallel load is not the issue.

Answer

The Aurora cluster was underprovisioned for parallel load

Answer

The DMS task was configured with 'ongoing replication' causing continuous write load

Answer

The DMS task replicated data to a different region, causing network latency

Question 2

A company is migrating an on-premises MongoDB database to Amazon DocumentDB. The migration must be online with minimal downtime. Which AWS service should be used?

Accepted Answer

AWS DMS. Option B is correct because AWS DMS supports MongoDB as a source and DocumentDB as a target with ongoing replication. Option A is wrong because Snowball is offline. Option C is wrong because S3 is not a migration tool. Option D is wrong because DataSync is for file storage.

Answer

AWS DataSync

Answer

AWS S3

Answer

AWS Snowball Edge

Question 3

A company uses a self-hosted MySQL database on EC2. They want to migrate to Amazon RDS for MySQL with minimal downtime and automated failover. Which migration strategy should be used?

Accepted Answer

Set up MySQL replication from EC2 to RDS, then cut over. Option D is correct because setting up replication from EC2 to RDS using MySQL native replication allows near-zero downtime cutover. Option A is wrong because dump/restore requires downtime. Option B is wrong because snapshot restore requires downtime. Option C is wrong because DMS might add complexity and is not necessary if native replication works.

Answer

Use mysqldump to export the database and import to RDS

Answer

Take a snapshot of the EC2 instance and restore to RDS

Answer

Use AWS DMS with full load and CDC

Question 4

A company is migrating a 10 TB Oracle database to Amazon Aurora PostgreSQL. The migration uses AWS DMS with CDC. After the full load, the CDC phase is falling behind by several minutes. The source Oracle database generates 500 MB of redo logs per minute. Which action will most likely improve CDC performance?

Accepted Answer

Increase the number of parallel apply threads on the DMS task. Option C is correct because increasing the DMS task's parallel apply threads can speed up the apply phase. Option A is wrong because increasing source redo log size does not affect DMS performance. Option B is wrong because disabling CDC is not a solution. Option D is wrong because reducing batch size would slow down processing.

Answer

Disable CDC and perform a full load only

Answer

Reduce the batch size in the DMS task settings

Answer

Increase the source Oracle redo log size

Question 5

A company needs to migrate a 100 GB on-premises SQL Server database to Amazon RDS for SQL Server. The migration must be completed within a 4-hour maintenance window. The network link has 500 Mbps throughput. Which approach should be used?

Accepted Answer

Use native SQL Server backup to S3, then restore to RDS. Option A is correct because native backup to S3 and restore to RDS is the fastest method for this size, and the network can transfer 100 GB in ~30 minutes. Option B is wrong because DMS with CDC adds complexity and is not needed. Option C is wrong because Snowball is unnecessary. Option D is wrong because EC2 is not needed.

Answer

Use AWS DMS with full load and CDC

Answer

Use AWS Snowball Edge to transfer the backup

Answer

Launch an EC2 instance with SQL Server, copy the database, and then migrate to RDS

Question 6

A company has a 200 GB PostgreSQL database on-premises and wants to migrate to Amazon RDS for PostgreSQL. The company requires encrypted data transfer and wants to minimize downtime. Which combination of services should be used?

Accepted Answer

Use AWS DMS with SSL and ongoing replication. Option B is correct because AWS DMS supports SSL encryption and CDC for minimal downtime. Option A is wrong because S3 does not provide database migration. Option C is wrong because EC2 instance is not needed. Option D is wrong because VPN alone does not migrate data.

Answer

Use native pg_dump to S3, then import to RDS

Answer

Use AWS VPN to connect on-premises to RDS and perform a database dump

Answer

Use an EC2 instance with PostgreSQL replication to RDS

Question 7

A company is migrating a 5 TB Oracle database to Amazon Aurora MySQL using AWS DMS. The full load completes successfully, but the CDC phase is slow and the target Aurora cluster is consuming high CPU. The DMS instance type is dms.c4.2xlarge. Which change will most likely improve CDC performance?

Accepted Answer

Increase the number of parallel apply threads in the DMS task. Option D is correct because increasing the number of parallel apply threads can improve throughput, reducing CPU strain on Aurora. Option A is wrong because increasing max_connections may not help. Option B is wrong because Aurora auto-scales storage. Option C is wrong because DMS uses its own storage, not target storage.

Answer

Increase the Aurora cluster's max_connections parameter

Answer

Increase the DMS task's target storage allocation

Answer

Change the Aurora cluster to a larger instance class

Question 8

Which TWO factors should be considered when selecting a migration method from on-premises Oracle to Amazon RDS for Oracle?

Accepted Answer

The size of the database and available network bandwidth. Correct: B (database size and network bandwidth determine the best approach) and D (downtime tolerance affects choice between online and offline migration). A is not a factor because RDS supports Oracle features; C is irrelevant; E is not a primary factor.

Answer

The version of the Oracle client used by applications

Answer

The number of stored procedures in the database

Answer

The number of indexes on the source database

Question 9

Which THREE actions should be taken to prepare for a migration of an on-premises MySQL database to Amazon RDS for MySQL with minimal downtime using AWS DMS?

Accepted Answer

Enable binary logging on the source MySQL database. Correct: A (enable binary logging for CDC), B (create a user with replication privileges), and E (set up an SSH tunnel for secure connection). C is not required; D is not necessary for DMS.

Answer

Disable foreign key checks on the source database

Answer

Take a full backup of the source database

Question 10

Which TWO AWS services can be used to migrate an on-premises SQL Server database to Amazon RDS for SQL Server?

Accepted Answer

AWS DMS. Correct: A (AWS DMS) and C (native backup/restore to S3). B is for NoSQL; D is for file storage; E is for data transfer between on-premises and S3, not database migration.

Answer

AWS DataSync

Answer

AWS Storage Gateway

Answer

AWS DynamoDB

Question 11

Refer to the exhibit. A company is migrating from an on-premises MySQL database to Amazon RDS for MySQL. The DBA wants to connect to the RDS instance using the endpoint shown. What additional step is required to allow the DBA's client to connect?

Accepted Answer

Modify the security group to allow inbound traffic on port 3306 from the client IP. Option C is correct because by default, RDS instances do not allow inbound traffic; a security group must allow traffic on port 3306. Option A is wrong because the endpoint is already public if the instance is public. Option B is wrong because the user already exists. Option D is wrong because the DNS endpoint is already provided.

Answer

Create a Route 53 record for the endpoint

Answer

Create a MySQL user that matches the client's IP

Answer

Change the RDS instance to be publicly accessible

Question 12

Refer to the exhibit. An IAM policy is attached to a user who will manage AWS DMS tasks. When the user tries to start a replication task, they receive an access denied error. What is the most likely cause?

Accepted Answer

The policy is missing permissions to describe endpoints and connections. Option A is correct because the policy does not include dms:StartReplicationTask, only dms:StartReplicationTask is not present (the action is StartReplicationTask, not StartReplicationTask? Actually the policy has StartReplicationTask, so that should be fine. Wait, the policy does include dms:StartReplicationTask. So the error might be due to missing DescribeEndpoints. Option D is plausible. Let's re-evaluate. The policy includes StartReplicationTask, so A is not correct. The user might need dms:DescribeEndpoints to start a task. So D is correct.

Answer

The policy does not allow rds:DescribeDBInstances

Answer

The policy does not allow the dms:StartReplicationTask action

Answer

The policy does not allow dms:CreateReplicationTask

Question 13

Refer to the exhibit. A DBA is monitoring a DMS migration task from on-premises Oracle to Amazon RDS for Oracle. The full load completed successfully with 50 tables. However, the DBA notices that the CDC phase has not started. What is the most likely reason?

Accepted Answer

The replication task was stopped after the full load completed. Option B is correct because if the task is stopped after full load, CDC will not start. The stop date is 1 hour after start, indicating the task stopped. Option A is wrong because tables loaded shows 50, not errored. Option C is wrong because DMS does not require manual CDC enable. Option D is wrong because the task might be stopped, not pending.

Answer

The task was not configured with CDC enabled

Answer

The full load encountered errors on some tables

Answer

The source Oracle database is not generating redo logs

Question 14

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 5 TB in size and has a daily change rate of 2%. The migration must have minimal downtime. Which migration strategy should be used?

Accepted Answer

Use AWS Database Migration Service (DMS) with ongoing replication from the source database.. AWS DMS with ongoing replication allows continuous data sync with minimal downtime. Option A (AWS SCT + DMS) is not ideal because SCT is for schema conversion, not needed here. Option C (export/import) causes downtime. Option D (RDS read replica) is for within AWS, not on-premises to RDS.

Answer

Use AWS Schema Conversion Tool (SCT) to convert the schema, then use AWS DMS for full load only.

Answer

Create an RDS read replica in the same region and promote it.

Answer

Export the database to a dump file using Oracle Data Pump, upload to S3, and restore to RDS.

Question 15

A company wants to migrate a 2 TB Amazon RDS for MySQL DB instance to Amazon Aurora MySQL. The migration must have zero downtime and must be reversible for 48 hours. Which strategy meets these requirements?

Accepted Answer

Create an Aurora MySQL Read Replica from the RDS MySQL instance, then promote the replica to a standalone Aurora cluster.. Creating an Aurora read replica from the RDS MySQL instance and then promoting it provides zero downtime and allows fallback by deleting the Aurora cluster. Option A (DMS with CDC) has potential downtime. Option C (snapshot restore) is irreversible. Option D (mysqldump) causes downtime.

Answer

Take a snapshot of the RDS MySQL instance, restore it to Aurora MySQL, and update the DNS.

Answer

Export the database using mysqldump, import into Aurora, and switch DNS.

Answer

Use AWS DMS with ongoing change data capture (CDC) to migrate to Aurora.