DBS-C01 Practice Test 23 — 15 Questions

Question 1

An administrator is setting up an AWS DMS replication instance and attaches the IAM policy shown in the exhibit. The administrator receives an error that the replication instance cannot be created. Which missing permission is the MOST likely cause?

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

Accepted Answer

ec2:DescribeSecurityGroups. When creating a DMS replication instance, AWS DMS needs to create and manage network interfaces in the customer's VPC. The `ec2:DescribeSecurityGroups` permission is required for DMS to validate and describe the security groups specified during replication instance creation. Without this permission, the service cannot verify the security group IDs, leading to a creation failure.

Answer

ec2:DescribeVpcPeeringConnections

Answer

ec2:CreateNetworkInterfacePermission

Answer

dms:CreateReplicationInstance

Question 2

A developer needs to migrate a 500 GB MongoDB database to Amazon DocumentDB. Which approach will minimize application downtime?

Accepted Answer

Use AWS DMS with ongoing replication from MongoDB to DocumentDB. AWS DMS with ongoing replication (change data capture) allows you to perform a full load of the existing 500 GB MongoDB data into DocumentDB while continuously replicating new changes from the source. This minimizes application downtime because you can cut over to DocumentDB only after the target is fully synchronized, rather than taking the source offline for the entire migration duration.

Answer

Write a custom script to migrate data in batches

Answer

Export data from MongoDB, upload to S3, and import into DocumentDB

Answer

Use AWS DataSync to transfer data files

Question 3

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

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS Database Migration Service (AWS DMS) is the correct choice because it supports both full-load migration of the initial 500 GB Oracle database and ongoing change data capture (CDC) replication to keep the target RDS for Oracle instance synchronized with minimal downtime. DMS uses Oracle LogMiner or binary reader to capture changes from the source redo logs and apply them continuously, enabling a near-zero downtime migration.

Answer

AWS Snowball Edge for offline data transfer

Answer

Amazon S3 to store backup files and restore

Answer

AWS DataSync

Question 4

A company is running an Amazon RDS for MySQL DB instance. The DB instance is experiencing high CPU utilization due to a sudden increase in read traffic. The company needs to reduce the load on the primary DB instance with minimal downtime. Which solution should be used?

Accepted Answer

Create an RDS read replica and redirect read queries to it.. Creating an Amazon RDS read replica allows you to offload read traffic from the primary DB instance to one or more read replicas, which can handle SELECT queries. This reduces CPU utilization on the primary instance with minimal downtime, as read replicas are asynchronous replicas that can be promoted to a primary if needed. Redirecting read queries to the read replica effectively distributes the load without requiring a change to the primary instance's configuration.

Answer

Modify the DB instance to a larger instance class.

Answer

Use an Amazon ElastiCache cluster to cache frequent queries.

Answer

Enable Multi-AZ on the DB instance.

Question 5

A user has the IAM policy shown in the exhibit. When attempting to create a DMS replication task, they receive an authorization error. What is the most likely missing permission?

Accepted Answer

dms:CreateEndpoint permission. The user is attempting to create a DMS replication task, which requires the ability to create the underlying DMS resources. The error indicates a missing permission for the `dms:CreateEndpoint` action, as DMS replication tasks depend on source and target endpoints that must be created first. Without this permission, the API call to create the endpoint fails, resulting in an authorization error.

Answer

ec2:DescribeSecurityGroups to allow network configuration

Answer

s3:PutObject for the S3 bucket

Answer

logs:CreateLogGroup to enable logging

Question 6

A developer accidentally deleted a production RDS for PostgreSQL DB instance. The company has automated backups enabled with a retention period of 7 days. What is the fastest way to restore the database to the state just before the deletion?

Accepted Answer

Create a new DB instance and use point-in-time recovery to the time just before deletion.. When automated backups are enabled, you can perform point-in-time recovery (PITR) to restore the database to any point within the retention period, including just before deletion. RDS retains the automated backups and transaction logs for the retention period even after the instance is deleted. Option A is incorrect because Amazon RDS does not use a Recycle Bin for DB instances. Option B is incorrect because restoring from the latest automated snapshot would not recover transactions after that snapshot; you need PITR to get the state just before deletion. Option C is incorrect because AWS DMS is for migrating data between databases, not for recovering a deleted instance.

Answer

Recover the instance from the Amazon RDS Recycle Bin.

Answer

Restore from the latest automated snapshot that was taken before deletion.

Answer

Use the AWS DMS to migrate the data from the deleted instance to a new one.

Question 7

A financial services company is migrating a 10 TB Oracle data warehouse to Amazon Redshift. The source database uses a combination of partitioned tables, indexes, and materialized views. The migration team plans to use AWS SCT and DMS. Which approach should the team take to optimize query performance after migration?

Accepted Answer

Define appropriate distribution keys and sort keys. Amazon Redshift is a columnar data warehouse that does not support traditional indexes or the PARTITION BY clause used in Oracle. Instead, query performance in Redshift is optimized by defining appropriate distribution keys (to minimize data shuffling across nodes) and sort keys (to enable zone maps and reduce the amount of data scanned). This approach directly addresses the performance needs of the migrated 10 TB data warehouse.

Answer

Create indexes on frequently queried columns

Answer

Recreate all materialized views using standard views

Answer

Partition tables by date using the PARTITION BY clause

Question 8

Match each AWS security feature to its purpose for databases.

Accepted Answer

AWS KMS: Encrypts data at rest and manages encryption keys. AWS KMS handles encryption keys, IAM controls access, Security Groups provide network firewall, and Secrets Manager manages credentials. Common confusions include mixing up KMS with IAM for key management vs. access control.

Answer

AWS KMS: Controls user access to resources

Answer

AWS IAM: Encrypts data at rest using keys

Question 9

Match each backup/restore concept to its AWS database feature.

Accepted Answer

Automated Backup: Automatically created daily backups of a DB instance with a retention period (RDS). Correct matches: Automated Backup corresponds to RDS automated backups (daily, retention period), Manual Snapshot corresponds to user-initiated RDS snapshots (stored in S3), and PITR corresponds to DynamoDB's ability to restore to any point in the last 35 days. Common confusions involve swapping the definitions of automated and manual backups.

Answer

Automated Backup: User-initiated backup of a DB instance stored in S3

Answer

Manual Snapshot: Automatically created daily backups with retention period

Question 10

A company wants to migrate an on-premises MySQL database to Amazon RDS for MySQL with minimal downtime. The database is 500 GB and has moderate write activity. Which approach is MOST suitable?

Accepted Answer

Use AWS Database Migration Service (DMS) with a full load and ongoing replication.. AWS DMS with full load and ongoing replication is the most suitable approach because it supports continuous change data capture (CDC) from the on-premises MySQL source to the Amazon RDS target, enabling minimal downtime. The full load transfers the initial 500 GB dataset, while ongoing replication applies incremental changes until cutover, meeting the requirement for minimal downtime with moderate write activity.

Answer

Use mysqldump to export the database, then import into RDS.

Answer

Use AWS Server Migration Service (SMS) to migrate the database server.

Answer

Create a read replica of the on-premises database and promote it to RDS.

Question 11

An IAM policy is attached to an application role that accesses a DynamoDB table named 'Orders'. The table has a global secondary index named 'OrderDateIndex'. The application needs to write new orders and query the index. Based on the exhibit, will the application be able to perform these operations?

Accepted Answer

Yes, the policy allows both writes and querying the index.. The IAM policy grants `dynamodb:PutItem` on the table and `dynamodb:Query` on the index. Since the policy explicitly allows both actions on their respective ARNs, the application can write new orders to the 'Orders' table and query the 'OrderDateIndex' global secondary index. Option B is correct because the policy covers both required operations.

Answer

Yes, but only writes are allowed; index queries are denied.

Answer

No, the policy does not grant access to the index.

Answer

No, the policy denies Query on the index.

Question 12

A company uses Amazon Aurora MySQL-Compatible Edition for its e-commerce platform. During flash sales, the database experiences high write contention on the 'orders' table, causing slow inserts and deadlocks. The development team wants to reduce contention without changing the application code. Which database design strategy is MOST effective?

Accepted Answer

Enable Aurora Multi-Master to allow multiple write nodes. Aurora Multi-Master enables multiple writer nodes to accept write operations concurrently, which directly reduces write contention on the 'orders' table during high-volume flash sales. Unlike single-master Aurora, Multi-Master allows each writer to handle inserts independently, minimizing deadlocks and improving throughput without requiring application code changes.

Answer

Implement manual sharding across multiple Aurora clusters

Answer

Add more read replicas to offload read traffic

Answer

Use a larger instance type with higher IOPS

Question 13

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 14

A company is migrating a 2 TB Oracle database to Amazon Aurora PostgreSQL. They need to minimize downtime. Which AWS service should they use?

Accepted Answer

AWS Database Migration Service (DMS). AWS DMS can perform a live migration from Oracle to Aurora PostgreSQL with minimal downtime by continuously replicating ongoing changes from the source database to the target using Change Data Capture (CDC). For a 2 TB database, DMS supports full-load plus CDC, allowing the source to remain operational during the initial load and then switching over with only a brief outage to apply final changes.

Answer

AWS Schema Conversion Tool (SCT)

Answer

AWS Data Pipeline

Answer

AWS Snowball

Question 15

A financial services company needs a database to store transaction records with strong consistency and the ability to run complex analytical queries. The data volume is in the terabytes and is expected to grow. The company also needs point-in-time recovery. Which AWS database solution meets these requirements?

Accepted Answer

Amazon Redshift with automated snapshots. Amazon Redshift is correct because it is a fully managed, petabyte-scale data warehouse designed for complex analytical queries on large datasets, and it supports automated snapshots for point-in-time recovery within a configurable retention period. The service provides strong consistency for committed transactions and can handle terabytes of data with columnar storage and massively parallel processing, making it ideal for the financial services company's requirements.

Answer

Amazon RDS for MySQL with read replicas

Answer

Amazon ElastiCache for Redis with AOF persistence

Answer

Amazon DynamoDB with on-demand backup