DBS-C01 Practice Exam 60 — 20 Questions

Question 1

A financial services firm is designing a ledger database that requires ACID transactions across multiple tables, strong consistency, and the ability to scale reads for reporting. The application uses PostgreSQL-compatible SQL and expects unpredictable read traffic. The firm wants a fully managed AWS service that automatically scales storage and provides high availability across three Availability Zones. Which service should they choose?

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

Accepted Answer

Amazon Aurora PostgreSQL with a writer and multiple reader instances. The ledger requires ACID transactions, strong consistency, PostgreSQL compatibility, automatic storage scaling, and high availability across three Availability Zones. Aurora PostgreSQL delivers all of these, with read scaling via multiple reader instances. RDS for PostgreSQL lacks automatic storage scaling and reader scaling in Multi-AZ, while DynamoDB and Redshift do not meet the PostgreSQL-compatible transactional requirements.

Answer

Amazon Redshift with concurrency scaling

Answer

Amazon RDS for PostgreSQL with Multi-AZ deployment

Answer

Amazon DynamoDB with transactions and global secondary indexes

Question 2

A financial services company runs an Amazon Aurora MySQL cluster in us-east-1 that must be replicated to eu-west-1 for disaster recovery. The RPO requirement is under one second and the RTO requirement is under one minute. The database team wants a managed solution that does not require them to administer any replication instances. Which deployment approach meets these requirements?

Accepted Answer

Create an Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in eu-west-1.. Aurora Global Database is purpose-built for cross-Region disaster recovery: it replicates storage at the physical layer with sub-second typical lag and allows promotion of a secondary cluster in under a minute. Because AWS manages the replication, no replication instances need administration, which directly matches the stated RPO and RTO requirements.

Answer

Create a cross-Region read replica of the Aurora cluster in eu-west-1 and promote it during a failover event.

Answer

Enable Aurora Multi-AZ with automatic failover and rely on the standby replica in eu-west-1 for disaster recovery.

Answer

Configure AWS Database Migration Service with change data capture from us-east-1 to an Aurora cluster in eu-west-1.

Question 3

A company is deploying an Amazon DynamoDB table that will be used by an application with unpredictable read traffic. The table must automatically scale read capacity to handle spikes while minimizing cost. Which solution should be used?

Accepted Answer

Use DynamoDB on-demand capacity mode.. DynamoDB on-demand capacity mode automatically scales to handle unpredictable traffic and charges per request, making it cost-effective for variable workloads. Provisioned mode with auto scaling or high RCUs does not provide the same seamless scaling and cost efficiency.

Answer

Use provisioned capacity mode with a high read capacity unit (RCU) setting to handle peaks.

Answer

Use provisioned capacity mode with auto scaling enabled for read capacity.

Answer

Use DynamoDB Accelerator (DAX) to cache reads and reduce the need for scaling.

Question 4

A company is migrating a small on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database is 50 GB and the company can afford a short downtime window. They want to use AWS DMS for the migration. Which DMS task type should they choose to perform the migration with the least complexity?

Accepted Answer

Full load only. For a small database with an acceptable downtime window, a full load task is the simplest DMS option. It copies existing data without the overhead of setting up change data capture or ongoing replication. This minimizes complexity and is sufficient when near-zero downtime is not required.

Answer

Full load and change data capture (CDC)

Answer

Full load with validation only

Answer

Change data capture (CDC) only

Question 5

A company is deploying a new Amazon RDS for MySQL database. They need to ensure that the database can be restored to any point in time within the last 7 days. Which feature should be enabled?

Accepted Answer

Automated backups. Automated backups are required for point-in-time recovery in Amazon RDS. When enabled, RDS continuously backs up the database and transaction logs, allowing restoration to any point within the retention period. This is the only feature that provides the required capability for restoring to any point in time within the last 7 days.

Answer

Manual snapshots

Answer

Multi-AZ deployment

Answer

Read replicas

Question 6

A company is planning to migrate an on-premises Microsoft SQL Server database to Amazon RDS for SQL Server. The database is 2 TB and the company wants to minimize downtime. They intend to use AWS Database Migration Service (AWS DMS) with ongoing replication. Which TWO actions should the company take to ensure that the migration captures ongoing changes efficiently? (Choose two.)

Accepted Answer

Set the AWS DMS task to use 'Full Load and CDC' mode.. To efficiently capture ongoing changes when migrating SQL Server to RDS for SQL Server with AWS DMS, you must enable MS-CDC on the source database and tables, and configure the DMS task to perform both full load and CDC. MS-CDC provides the mechanism for DMS to read changes, while the task mode ensures that changes are replicated after the initial load. These two actions together enable minimal downtime migration.

Answer

Create a new AWS DMS replication instance with Multi-AZ enabled.

Answer

Configure the source database to use the 'Simple' recovery model.

Answer

Enable Transparent Data Encryption (TDE) on the source database.

Question 7

A company is migrating an on-premises Microsoft SQL Server database to Amazon RDS for SQL Server. The database uses SQL Server Agent jobs and linked servers. After migration, the jobs and linked servers must continue to function. Which action should be taken to meet these requirements?

Accepted Answer

Use the native backup and restore method to migrate the database, then reconfigure SQL Server Agent jobs and linked servers on the RDS instance.. SQL Server Agent jobs and linked servers are not part of a database backup, so they must be manually recreated on the RDS instance after migration. Native backup and restore is a supported method for migrating the database itself, and then you can script and deploy the jobs and linked servers using T-SQL. Other migration methods do not handle these instance-level objects.

Answer

Use AWS DMS to migrate the database, and DMS will automatically migrate SQL Server Agent jobs and linked servers.

Answer

Use the RDS for SQL Server native backup and restore, and RDS will automatically enable and configure SQL Server Agent and linked servers based on the backup.

Answer

Use the AWS Schema Conversion Tool (AWS SCT) to convert the database, and it will also migrate SQL Server Agent jobs and linked servers.

Question 8

A company is deploying Amazon DynamoDB for a new application that requires a recovery point objective (RPO) of 5 minutes and a recovery time objective (RTO) of 1 hour across two AWS Regions. The application must continue to serve reads and writes in the secondary Region if the primary Region fails. Which deployment strategy should a database specialist recommend?

Accepted Answer

Configure DynamoDB global tables with the primary table in the primary Region and a replica table in the secondary Region.. DynamoDB global tables replicate data across Regions with sub-second to low-second latency, satisfying the 5-minute RPO, and provide an active-active replica that can accept reads and writes during a Regional failure. Because the data already exists in the secondary Region, failover is fast and meets the 1-hour RTO. PITR, custom Streams replication, and DAX do not provide multi-Region active-active replication.

Answer

Set up DynamoDB Streams on the primary table and use an AWS Lambda function to replicate items to a table in the secondary Region.

Answer

Enable DynamoDB point-in-time recovery (PITR) on the table and restore it to a new table in the secondary Region during a failover.

Answer

Create a DynamoDB Accelerator (DAX) cluster in each Region and point the application to the local cluster for reads and writes.

Question 9

A logistics company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database is 4 TB and must be migrated with less than 10 minutes of downtime. The company has set up an AWS Direct Connect connection and wants to use AWS DMS. Which combination of source endpoint settings and AWS DMS task configuration will achieve the required minimal downtime?

Accepted Answer

Use Oracle LogMiner with change data capture (CDC) and a full load plus ongoing replication task.. To achieve minimal downtime, AWS DMS must perform a full load to copy existing data and then use change data capture (CDC) to replicate ongoing changes. Oracle LogMiner is the supported CDC method for Oracle sources. A full load plus ongoing replication task allows the target to stay synchronized until cutover. Other options either lack CDC, use unsupported methods, or introduce manual steps that increase downtime.

Answer

Use Oracle Binary Reader with a full load only task and then manually apply changes after the load.

Answer

Use Oracle LogMiner with a full load only task and then perform a second full load to capture changes.

Answer

Use Oracle Data Pump to export and import the database, then use AWS DMS for ongoing replication.

Question 10

A company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database uses a non-standard block size of 16 KB and the company wants to use Oracle Data Pump for the migration. They have created an RDS for Oracle instance with the default block size. During the import, they encounter errors indicating that the data pump file cannot be imported due to block size mismatch. What should the company do to resolve this issue?

Accepted Answer

Create a new RDS for Oracle instance with a matching 16 KB block size and perform the import there.. Amazon RDS for Oracle requires the database block size to be specified at instance creation and it cannot be changed afterward. When migrating using Data Pump, the export file's block size must match the target database's block size. Therefore, creating a new RDS instance with the same 16 KB block size is necessary to successfully import the Data Pump file.

Answer

Modify the RDS for Oracle instance to change the block size to 16 KB using the MODIFY DATABASE command.

Answer

Use Oracle GoldenGate to replicate the data instead of Data Pump, as it is block size agnostic.

Answer

Convert the Data Pump export file to use the default block size using the DBMS_DATAPUMP package.

Question 11

A company runs an Amazon Aurora MySQL cluster with two Aurora Replicas. The database specialist must ensure that read-only application queries are distributed evenly across the replicas and that a replica failure does not interrupt reads. Which approach should the specialist use?

Accepted Answer

Configure the application to connect to the reader endpoint of the Aurora cluster.. The Aurora reader endpoint is designed to load-balance read-only connections across all Aurora Replicas and automatically removes unhealthy replicas from rotation. Using the cluster endpoint sends reads to the writer, while custom load balancing or hardcoded endpoints add unnecessary complexity and do not handle failover gracefully. The reader endpoint directly satisfies both even distribution and fault tolerance.

Answer

Create a Network Load Balancer that targets the Aurora Replicas and point the application to the load balancer.

Answer

Configure the application to connect to the cluster endpoint and rely on Aurora to load-balance reads.

Answer

Manually configure the application with the individual endpoints of each Aurora Replica and implement client-side round-robin.

Question 12

A company is migrating an on-premises MongoDB database to Amazon DocumentDB (with MongoDB compatibility). The database is 2 TB and the migration must be completed with minimal downtime. The company has an AWS Direct Connect connection with 1 Gbps bandwidth. They plan to use AWS Database Migration Service (AWS DMS). Which migration approach will meet these requirements?

Accepted Answer

Use AWS DMS with a change data capture (CDC) task to replicate ongoing changes after an initial full load.. AWS DMS supports MongoDB as a source and Amazon DocumentDB as a target. To achieve minimal downtime, you should use a CDC task that performs a full load and then replicates ongoing changes. This keeps the target synchronized until you are ready to cut over, which only requires a brief pause in writes. The Direct Connect bandwidth is sufficient for the initial load and ongoing replication of a 2 TB database.

Answer

Use AWS Snowball Edge to transfer the data to Amazon S3, then use AWS DMS to load from S3 into Amazon DocumentDB.

Answer

Use AWS DMS with a full load only task and schedule it during a maintenance window.

Answer

Use the mongodump and mongorestore utilities to export and import the data, then enable change streams for ongoing replication.

Question 13

A database specialist is managing an Amazon RDS for SQL Server DB instance with Multi-AZ enabled. The specialist needs to perform a minor version upgrade during a maintenance window. The upgrade requires a failover to the standby instance. What is the expected behavior during this operation?

Accepted Answer

The standby instance is upgraded first, then a failover occurs, and the former primary instance is upgraded.. For a minor version upgrade on an RDS for SQL Server Multi-AZ instance, Amazon RDS upgrades the standby first, then performs a failover to the upgraded standby, and finally upgrades the former primary. This approach minimizes downtime because the primary remains available until the failover, and the failover typically completes within 60-120 seconds.

Answer

The primary instance is upgraded first, causing a brief outage, and then the standby is upgraded without failover.

Answer

The standby instance is upgraded first, then a failover occurs, and the primary instance is upgraded while the standby takes over.

Answer

Both the primary and standby instances are upgraded simultaneously, resulting in a brief outage.

Question 14

A company is deploying a new Amazon RDS for SQL Server database in a Multi-AZ configuration. The database must be encrypted at rest using AWS Key Management Service (AWS KMS). The company wants to automate the deployment using AWS CloudFormation. Which CloudFormation resource property should be used to enable encryption?

Accepted Answer

StorageEncrypted: true. In AWS CloudFormation, the StorageEncrypted property of the AWS::RDS::DBInstance resource is used to enable encryption at rest. Setting it to true encrypts the underlying storage using AWS KMS. If a specific KMS key is required, you can also specify the KmsKeyId property. However, StorageEncrypted is the key property that enables encryption. Encryption must be enabled at instance creation and cannot be added later without recreating the instance.

Answer

Encrypted: true

Answer

EnableEncryption: true

Answer

KmsKeyId: arn:aws:kms:region:account:key/key-id

Question 15

A company is deploying a new Amazon DynamoDB table. The table will store user session data that must be automatically deleted after 30 days. The company wants to minimize costs and administrative overhead. Which feature should be used?

Accepted Answer

Configure a DynamoDB TTL attribute and set it to the session expiration timestamp.. DynamoDB TTL is the ideal feature for automatically deleting expired items. It requires only setting an attribute with an expiration timestamp, and DynamoDB deletes items after that time without additional cost or administrative effort. Other methods involve custom code, scans, or manual restores, which increase complexity and cost. TTL is designed exactly for this use case.

Answer

Use a scheduled Amazon EventBridge rule to invoke a Lambda function that scans and deletes old items.

Answer

Enable point-in-time recovery and restore the table without expired items.

Answer

Enable DynamoDB Streams and use AWS Lambda to delete expired items.

Question 16

A company uses Amazon DynamoDB with a table that has a global secondary index (GSI). The GSI is experiencing throttling events. The database specialist needs to identify the cause. Which action should be taken?

Accepted Answer

Check the GSI's provisioned write capacity and increase it if necessary.. GSIs have their own provisioned throughput, separate from the base table. Throttling on a GSI typically occurs when its write capacity is insufficient for the write workload. The specialist should check the GSI's consumed and provisioned write capacity metrics in CloudWatch and increase the GSI's write capacity if it is the bottleneck. This directly resolves the throttling.

Answer

Enable DynamoDB Streams on the table to capture throttled writes.

Answer

Increase the write capacity of the base table to resolve the GSI throttling.

Answer

Modify the GSI to use on-demand capacity mode.

Question 17

A company runs an Amazon Aurora MySQL cluster with a writer instance and two reader instances. The database specialist needs to ensure that automated backups are retained for 14 days, but the current backup retention period is 7 days. The specialist modifies the retention period to 14 days using the AWS Management Console. What is the immediate effect of this change?

Accepted Answer

The change takes effect immediately, and all existing automated backups will be retained for 14 days from their original creation date.. Increasing the backup retention period for an Aurora MySQL cluster takes effect immediately without requiring a restart. Existing automated backups are retained based on the new retention period, calculated from each backup's creation date. Backups older than the new retention window are eventually deleted. This ensures that the company can retain backups for 14 days as required.

Answer

The change will only affect future automated backups; existing backups will continue to be retained for 7 days.

Answer

The change requires a cluster restart to take effect, and during the restart, automated backups are suspended.

Answer

The existing automated backups will be retained for 14 days from the time of the change, and new backups will also be retained for 14 days.

Question 18

A media company stores metadata in an Amazon DynamoDB table with on-demand capacity mode. Users report sporadic HTTP 500 errors from the application, and CloudWatch shows spikes in `ThrottledRequests` for the table. A database specialist must determine which two factors can cause on-demand tables to throttle requests even though the table is not provisioned with fixed capacity. (Choose two.)

Accepted Answer

A sudden burst of traffic exceeds double the table's previous peak throughput within a short window.. On-demand tables are not immune to throttling: they enforce per-partition throughput limits, and a hot partition from a low-cardinality key can exceed them. They also have a burst absorption limit of roughly double the previous peak, after which requests may be throttled until capacity scales. Both factors can produce sporadic `ThrottledRequests` even without provisioned capacity.

Answer

The table has DynamoDB Streams enabled, and the stream's shard iterator has expired, blocking new writes.

Answer

The table is using strongly consistent reads, which consume twice the read capacity units of eventually consistent reads.

Answer

The table's previous peak traffic was much higher than the current traffic, so DynamoDB has not yet adjusted the baseline throughput downward.

Question 19

A database specialist manages an Amazon Aurora MySQL cluster that contains a writer instance and two reader instances. The team wants read-only connections distributed automatically across the two reader instances and wants unhealthy readers removed from rotation without any application-side changes. Which solution should the specialist implement?

Accepted Answer

Point the application at the Aurora reader endpoint, which load balances connections across the reader instances and removes unhealthy readers.. The Aurora reader endpoint is the built-in mechanism for distributing read-only connections across reader instances and automatically excluding unhealthy readers. It requires no application changes because the endpoint hostname stays constant while Aurora manages the underlying instances. Custom endpoints, load balancers, and DNS weighting all require manual management and do not remove unhealthy readers transparently.

Answer

Create a Route 53 weighted routing policy with one record per reader instance and configure health checks for each record.

Answer

Place an Application Load Balancer in front of the reader instances and register each reader instance's IP address as a target.

Answer

Create an Aurora custom endpoint that includes the two reader instances and point the application at that endpoint.

Question 20

A company runs an Amazon DynamoDB table with provisioned capacity. The table has a global secondary index (GSI) with its own provisioned throughput. The application team reports that write operations to the base table are succeeding, but some queries against the GSI are returning ProvisionedThroughputExceededException errors. The database specialist needs to resolve the issue with minimal application changes. What should the specialist do?

Accepted Answer

Increase the read capacity units (RCUs) of the global secondary index.. A global secondary index in DynamoDB has its own provisioned read and write capacity, independent of the base table. When queries against the GSI are throttled with ProvisionedThroughputExceededException, it indicates that the GSI's read capacity is insufficient. Increasing the GSI's RCUs directly resolves the throttling without requiring application changes. This is the most targeted and minimal change.

Answer

Increase the write capacity units (WCUs) of the base table.

Answer

Enable auto scaling on the base table only.

Answer

Switch the table to on-demand capacity mode.