DBS-C01 Practice Test 22 — 15 Questions

Question 1

A company is migrating a 5 TB SQL Server database to Amazon RDS for SQL Server. The migration must be completed within 48 hours with minimal downtime. The network bandwidth between on-premises and AWS is 500 Mbps. What is the MOST efficient migration strategy?

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

Accepted Answer

Use AWS Snowball to transfer the full database to an RDS instance, then use AWS DMS for ongoing replication. A 5 TB database over 500 Mbps would take approximately 23 hours for the initial full load alone (5 TB * 8 / 500 Mbps = 80,000 seconds ≈ 22.2 hours), leaving insufficient time for ongoing replication within the 48-hour window. AWS Snowball provides a physical transfer of the full database, bypassing network constraints, and then AWS DMS can perform ongoing change data capture (CDC) replication to apply incremental changes with minimal downtime.

Answer

Upgrade network bandwidth to 10 Gbps using AWS Direct Connect

Answer

Use AWS Database Migration Service (AWS DMS) with ongoing replication

Answer

Use AWS Schema Conversion Tool (AWS SCT) to migrate the schema, then use bulk insert

Question 2

A company runs a critical PostgreSQL database on Amazon RDS Multi-AZ. They need to perform a major version upgrade (e.g., from 12 to 13) with minimal downtime. Which approach should they take?

Accepted Answer

Create a read replica of the DB instance, perform the major version upgrade on the replica, then promote the replica to a new primary and update the connection string.. It leverages Amazon RDS read replicas to perform a major version upgrade with minimal downtime. By creating a read replica, upgrading it to PostgreSQL 13, and then promoting it to a new primary, you avoid any downtime on the original primary during the upgrade process. The promotion is a fast operation, and traffic is redirected by updating the connection string, resulting in only a brief interruption.

Answer

Take a snapshot, restore as a new instance with the upgraded engine version, and redirect traffic.

Answer

Initiate a major version upgrade directly on the Multi-AZ instance; the upgrade will be applied during the next maintenance window with minimal downtime.

Answer

Modify the DB instance to disable Multi-AZ, perform the upgrade, then re-enable Multi-AZ.

Question 3

A financial services company needs to store trade data with strong consistency, high durability, and the ability to run complex SQL queries on the data. The data volume is 10 TB and grows by 1 GB per day. Queries must return results in less than 5 seconds. Which database solution best meets these requirements?

Accepted Answer

Amazon Aurora. Amazon Aurora is the correct choice because it is a fully relational, ACID-compliant database that provides strong consistency, high durability (6-way replication across 3 AZs), and supports complex SQL queries. With 10 TB of data and 1 GB/day growth, Aurora can scale storage automatically up to 128 TB and, using features like Aurora Serverless or provisioned instances with read replicas, can achieve sub-5-second query performance for complex analytical queries when properly indexed and optimized.

Answer

Amazon DynamoDB

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Amazon DocumentDB

Answer

Amazon Redshift

Question 4

A company is migrating an Oracle database to Amazon RDS for Oracle. Security policy requires that all database connections be encrypted in transit. The security team wants to enforce that clients must use TLS 1.2 or higher. How can this be achieved?

Accepted Answer

Set the rds.force_ssl parameter to 1 in the DB parameter group.. Amazon RDS for Oracle supports SSL/TLS encryption, and setting the rds.force_ssl parameter to 1 in the DB parameter group enforces SSL connections, which ensures all connections use TLS 1.2 or higher (as per Oracle's implementation). Option A is incorrect because modifying the DB subnet group controls network-level access, not encryption requirements. Option B is incorrect because IAM policies cannot enforce encryption in transit at the database level; they can only control authentication and authorization. Option C is incorrect because require_secure_transport is a MySQL parameter, not applicable to Oracle.

Answer

Modify the DB subnet group to only allow traffic from specific IP ranges.

Answer

Create an IAM policy that denies access unless the connection uses TLS.

Answer

Set the require_secure_transport parameter to ON in the DB parameter group.

Question 5

A startup is building a social media application. User profiles, posts, and comments have relationships but the team expects rapid growth and wants to scale horizontally with no single points of failure. They need a database that supports flexible schemas for different content types. Which database service is most appropriate?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the most appropriate choice because it is a fully managed NoSQL key-value and document database that supports flexible schemas, enabling the application to handle user profiles, posts, and comments with varying attributes. It scales horizontally by automatically partitioning data across multiple nodes, and its multi-AZ replication eliminates single points of failure, meeting the startup's requirements for rapid growth and high availability.

Answer

Amazon Neptune

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Amazon Redshift

Answer

Amazon RDS for MySQL

Question 6

A startup needs a cost-effective database for a small application that handles both transactional and analytical workloads. They expect low traffic initially but want the database to automatically scale as the business grows. Which database solution is BEST suited?

Accepted Answer

Amazon Aurora Serverless v2. Amazon Aurora Serverless v2 is the best fit because it automatically scales compute and memory capacity in fine-grained increments (down to 1 ACU) based on actual workload demand, supporting both transactional (OLTP) and analytical (OLAP) queries via the MySQL/PostgreSQL-compatible Aurora engine. It offers a pay-per-ACU model that is cost-effective for low-traffic startups while providing near-instant scaling to handle growth without manual intervention.

Answer

Amazon DynamoDB with on-demand capacity

Answer

Amazon RDS for MySQL with a Single-AZ deployment

Answer

Amazon Redshift Serverless

Question 7

A startup is building a real-time leaderboard for a mobile game using Amazon DynamoDB. The leaderboard must update frequently and support global access with low latency. Which database design approach is most suitable?

Accepted Answer

Use Amazon DynamoDB global tables with appropriate partition key design.. Amazon DynamoDB global tables provide multi-Region, fully managed, multi-master replication, which is ideal for a real-time leaderboard requiring frequent updates and low-latency global access. By designing an appropriate partition key (e.g., game ID or time-based composite key), you can distribute write traffic evenly and avoid hot partitions, ensuring consistent performance under high update frequency.

Answer

Use Amazon ElastiCache for Redis with replication across Regions.

Answer

Use Amazon Aurora Global Database with a single writer and multiple readers.

Answer

Use Amazon S3 with event notifications to update a leaderboard file.

Question 8

A developer accidentally deleted a table in an Amazon RDS for PostgreSQL DB instance. The instance has automated backups enabled with a retention period of 7 days. The deletion occurred 2 hours ago. What is the quickest way to recover the table?

Accepted Answer

Perform a point-in-time recovery to a time just before the deletion.. Point-in-time recovery (PITR) allows restoring the RDS for PostgreSQL DB instance to any time within the 7-day backup retention period. Since the deletion occurred 2 hours ago, you can restore the instance to a time just before the deletion, then connect to the restored instance and extract the deleted table using pg_dump or similar tools. This is the quickest method because it does not require restoring a full snapshot and then applying transaction logs manually. Option B is incorrect because pg_dump cannot export a table that has already been deleted from the current instance. Option C is incorrect because automated backup files are not directly accessible as downloadable files from S3; they are used internally by RDS for PITR. Option D is incorrect because restoring from the latest automated snapshot would not recover the table if the snapshot was taken after the deletion, or if the snapshot includes the deletion state.

Answer

Use PostgreSQL pg_dump to connect and dump the table from the current instance.

Answer

Download the automated backup file from S3 and restore the table.

Answer

Restore the DB instance from the latest automated snapshot.

Question 9

A company uses Amazon ElastiCache for Redis and needs to encrypt data in transit between the application and the cache cluster. Which feature should be enabled?

Accepted Answer

Enable encryption in transit on the replication group.. Amazon ElastiCache for Redis supports encryption in transit using TLS (Transport Layer Security) when enabled on the replication group. This ensures data is encrypted between the application and the cache cluster. Option B is incorrect because encryption at rest protects data stored on disk, not data in transit. Option C is incorrect because AWS KMS customer master keys are used for encryption at rest, not for transit encryption. Option D is incorrect because VPC security groups control network access at the IP/port level, not encryption; allowing HTTPS traffic does not enable encryption for ElastiCache communication.

Answer

Enable encryption at rest.

Answer

Use AWS KMS customer master keys.

Answer

Configure the VPC security group to allow only HTTPS traffic.

Question 10

A security engineer is designing access controls for an Amazon DynamoDB table containing customer data. Which TWO actions enforce least privilege access?

Accepted Answer

Use IAM conditions to restrict access to specific attributes.. Options A and C are correct. Using IAM conditions to restrict access to specific attributes (A) and implementing fine-grained access control using IAM policy conditions (C) both enforce least privilege by limiting the data and actions a user can access. Option B violates least privilege by granting all actions to all users. Option D is incorrect because Amazon DynamoDB does not support resource-based policies; access is controlled via identity-based IAM policies. Option E is incorrect because a VPC endpoint policy allowing all actions does not restrict access.

Answer

Grant dynamodb:* action to all users.

Answer

Use a resource-based policy on the DynamoDB table.

Answer

Attach a VPC endpoint policy that allows all actions.

Question 11

Refer to the exhibit. A database administrator is trying to use AWS DMS to migrate data from an on-premises Oracle database to Amazon RDS for Oracle. The DMS replication instance is in the same VPC as the RDS instance. The administrator receives an access denied error when starting the replication task. The IAM policy attached to the DMS replication instance is shown. What is the MOST likely cause of the error?

Accepted Answer

The IAM policy does not include permissions for the source database endpoint. The error occurs because the IAM policy attached to the DMS replication instance does not include the necessary permissions to access the source Oracle database endpoint. Specifically, the policy lacks actions like `dms:TestConnection` and `dms:DescribeEndpoints` that are required for DMS to validate and connect to the source endpoint. Without these permissions, DMS cannot establish the connection to the on-premises Oracle database, resulting in an access denied error when starting the replication task.

Answer

The IAM policy does not allow the dms:CreateReplicationInstance action

Answer

The RDS instance is not in the same VPC as the DMS replication instance

Answer

The DMS replication instance is not associated with the IAM role

Question 12

A company wants to deploy a highly available Amazon RDS for MySQL database across two Availability Zones. Which feature should be enabled?

Accepted Answer

Multi-AZ deployment. Multi-AZ deployment synchronously replicates data to a standby instance in a different Availability Zone, providing automatic failover in case of an AZ outage. This is the correct feature for achieving high availability across two Availability Zones, as it ensures minimal downtime without manual intervention.

Answer

Read replicas in a different AZ

Answer

Automated backups with retention

Answer

Enhanced Monitoring

Question 13

A company is designing a database for a mobile application that requires offline synchronization. Users should be able to read and write data while offline, and changes should sync when connectivity is restored. Which AWS service supports this pattern?

Accepted Answer

AWS AppSync with Amazon DynamoDB. AWS AppSync with Amazon DynamoDB is correct because AppSync provides managed GraphQL APIs that support offline data synchronization via its client SDKs. When a mobile app is offline, mutations are queued locally and automatically replayed against DynamoDB once connectivity is restored, using a conflict resolution mechanism (e.g., last-writer-wins or custom resolvers) to merge changes.

Answer

Amazon RDS Proxy

Answer

Amazon S3 Transfer Acceleration

Answer

Amazon Cognito

Question 14

A company is migrating a 10 GB MySQL database to Amazon RDS for MySQL. They have a 1 Gbps connection to AWS. The migration must be completed in the least amount of time with minimal manual effort. Which tool should be used?

Accepted Answer

AWS Database Migration Service (DMS).. AWS Database Migration Service (DMS) is the correct choice because it can perform a live, continuous migration of a 10 GB MySQL database to Amazon RDS for MySQL with minimal downtime and manual effort. DMS handles schema conversion (if needed), data replication, and ongoing changes via Change Data Capture (CDC), allowing the migration to complete in the least amount of time while automatically managing the full load and sync process over the 1 Gbps connection.

Answer

AWS Schema Conversion Tool (SCT).

Answer

AWS Snowball Edge.

Answer

mysqldump and mysql command-line tools.

Question 15

A company is implementing fine-grained access control for a DynamoDB table named UserSessions. The table has a partition key of 'user_id'. The above IAM policy is attached to an IAM role assumed by the application. What does this policy achieve?

Accepted Answer

Restricts the application to access only items where the partition key matches the user's AWS user ID. The IAM policy uses a condition key `dynamodb:LeadingKeys` with a value of `${aws:userid}`. This restricts access to items in the DynamoDB table where the partition key (`user_id`) matches the unique identifier of the IAM user or role that is making the request. This implements fine-grained access control, ensuring the application can only read or write items belonging to the authenticated user.

Answer

Allows the application to perform all operations on the UserSessions table without restrictions

Answer

Allows the application to read but not write items in the UserSessions table

Answer

Allows the application to access only the UserSessions table but not other tables