DBS-C01 Practice Exam 65 — 20 Questions

Question 1

A company is migrating a large on-premises MongoDB database to Amazon DocumentDB. The migration must be completed with minimal downtime. The database is 500 GB and has a high write throughput. Which AWS service should be used to perform the migration?

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

Accepted Answer

AWS Database Migration Service (AWS DMS) with ongoing replication. AWS DMS supports MongoDB to Amazon DocumentDB migrations with ongoing replication, enabling minimal downtime. It performs a full load and then continuously replicates changes, so the cutover can be quick. Native tools or offline methods would cause significant downtime and are not suitable for high write throughput.

Answer

AWS Snowball Edge

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AWS DataSync

Answer

MongoDB native tools like mongodump and mongorestore

Question 2

A company is deploying a new Amazon RDS for PostgreSQL database that must support a read-heavy web application. The database will be in a single Availability Zone to reduce cost, but the company requires automated backups and the ability to restore to any point in time within the retention period. Which RDS feature should be enabled?

Accepted Answer

Automated backups with a retention period. Automated backups in Amazon RDS capture daily snapshots and transaction logs, enabling point-in-time recovery to any moment within the retention period. This feature works in single-AZ deployments and is the standard way to achieve PITR without the cost of Multi-AZ.

Answer

Multi-AZ deployment

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RDS Proxy

Answer

Read replicas in multiple Availability Zones

Question 3

A company is deploying a new Amazon Aurora MySQL cluster. They need to ensure that the database can be restored to any point in time within the last 35 days, and that automated backups are retained even if the cluster is deleted. The backup retention period must be set to 35 days. Which combination of actions should a database specialist take?

Accepted Answer

Configure the backup retention period to 35 days and enable the 'Retain automated backups' option when deleting the cluster.. To meet both PITR and post-deletion retention, set the backup retention period to 35 days and select the option to retain automated backups when deleting the cluster. This ensures automated backups are preserved for the retention period even after the cluster is gone.

Answer

Enable automated backups with a retention period of 35 days and enable the 'Copy tags to snapshots' option.

Answer

Set the backup retention period to 35 days and take a manual snapshot before deleting the cluster.

Answer

Enable automated backups with a retention period of 35 days and enable deletion protection on the cluster.

Question 4

A company is deploying a new Amazon DynamoDB table for a high-traffic application. They need to ensure that the table can handle sudden spikes in read and write traffic without manual intervention. Which DynamoDB capacity mode should they choose?

Accepted Answer

On-demand capacity mode. On-demand capacity mode is designed for workloads with unpredictable traffic patterns. It automatically scales to handle sudden spikes without manual intervention, and you pay only for the read and write requests you use. This makes it the best choice for high-traffic applications with variable demand.

Answer

Provisioned capacity mode with auto scaling enabled

Answer

Global tables with provisioned capacity

Answer

Reserved capacity mode

Question 5

A media company is designing a new analytics platform that will ingest millions of time-series metrics per minute from IoT sensors. The data will be queried primarily by timestamp ranges and by sensor ID, with high write throughput and automatic scaling of storage. The team wants a fully managed AWS database that is optimized for time-series workloads and supports built-in time-series functions. Which AWS service should they choose?

Accepted Answer

Amazon Timestream. Amazon Timestream is the only AWS service specifically designed for time-series data, offering automatic scaling, built-in time-series functions, and optimized storage for high-ingest workloads. The other options are general-purpose databases that would require significant custom development and management to meet the same requirements.

Answer

Amazon DynamoDB with a time-based sort key

Answer

Amazon Aurora MySQL with a partitioned table

Answer

Amazon Redshift with sort keys on timestamp

Question 6

A company is migrating a MySQL database to Amazon Aurora MySQL. The current database uses multi-statement transactions with read committed isolation level. The application frequently encounters deadlocks on the source database. Which Aurora MySQL feature can help reduce deadlocks without application changes?

Accepted Answer

Use Amazon RDS Proxy to pool and share database connections.. RDS Proxy helps reduce deadlocks by pooling and reusing database connections, which minimizes the overhead of establishing new connections and reduces contention on database resources. In MySQL, deadlocks often occur when multiple transactions compete for the same resources under high connection churn; by maintaining a stable pool of connections, RDS Proxy lowers the probability of concurrent conflicting locks. Since the proxy is transparent to the application, no code changes are required to benefit from this behavior.

Answer

Use Amazon Aurora Auto Scaling to automatically adjust the number of replicas.

Answer

Use Amazon Aurora Global Database to replicate data to multiple regions.

Answer

Use Amazon Aurora Backtrack to quickly revert transactions.

Question 7

A startup runs a small internal reporting tool on Amazon RDS for PostgreSQL. The workload is predictable, runs only during business hours, and the team wants to minimize cost while retaining the ability to scale storage automatically. Which configuration best fits these requirements?

Accepted Answer

A Single-AZ deployment with General Purpose SSD storage and storage autoscaling enabled.. A Single-AZ RDS for PostgreSQL instance with General Purpose SSD and storage autoscaling aligns cost with a small, predictable, business-hours reporting workload. It avoids paying for Multi-AZ redundancy, Provisioned IOPS, or a serverless minimum capacity floor, while autoscaling prevents storage-full outages without manual intervention.

Answer

An Amazon RDS for PostgreSQL instance using magnetic storage with automated backups disabled.

Answer

An Amazon Aurora Serverless v2 cluster with a minimum capacity of 8 ACUs.

Answer

A Multi-AZ deployment with Provisioned IOPS storage and a read replica.

Question 8

A gaming company uses Amazon DynamoDB to store player state. The table has a partition key of PlayerID and no sort key. The game experiences sudden spikes in write traffic during special events, causing ProvisionedThroughputExceededException errors. The team wants to avoid throttling while minimizing cost. Which action should a database specialist take?

Accepted Answer

Switch the table to on-demand capacity mode.. On-demand capacity mode is designed for unpredictable workloads and automatically scales to handle sudden spikes in write traffic without throttling. It charges per request, so the company pays only for what it uses, minimizing cost during low-traffic periods while ensuring availability during special events.

Answer

Enable auto scaling with a high maximum WCU limit.

Answer

Increase the provisioned write capacity units (WCUs) significantly.

Answer

Enable DynamoDB Accelerator (DAX) for the table.

Question 9

A company uses Amazon DynamoDB with a table that has a partition key of 'CustomerID' and a sort key of 'OrderDate'. The table is configured with on-demand capacity mode. During a marketing campaign, the application experiences a sudden increase in write traffic. The operations team notices that some write requests are being throttled with 'ProvisionedThroughputExceededException' errors, even though the table is in on-demand mode. Which of the following is the MOST likely explanation for these throttling errors?

Accepted Answer

The write traffic is concentrated on a few partition key values, causing a hot partition that exceeds the per-partition throughput limit.. In DynamoDB on-demand mode, throttling can still occur if a single partition exceeds its throughput limit. This happens when write traffic is concentrated on a few partition key values, creating a hot partition. The other options are less likely given the scenario.

Answer

The table's sort key 'OrderDate' is causing an uneven distribution of data across partitions, leading to throttling.

Answer

The on-demand capacity mode requires a warm-up period after a sudden traffic increase, during which throttling can occur.

Answer

The table's on-demand capacity mode has a default maximum throughput limit that is being exceeded.

Question 10

A healthcare company needs to store patient records in a database that must support complex transactions with ACID compliance and enforce referential integrity. The database must also be highly available across multiple Availability Zones and support automatic failover. The company wants to minimize administrative overhead. Which AWS service should they use?

Accepted Answer

Amazon Aurora with Multi-AZ deployment. The requirements include ACID compliance, referential integrity, high availability, automatic failover, and minimal administrative overhead. Amazon Aurora with Multi-AZ meets all these: it is a relational database supporting ACID and referential integrity, and Multi-AZ provides automatic failover with minimal management. Other services either lack relational features or are not optimized for transactional workloads.

Answer

Amazon DynamoDB with global tables

Answer

Amazon RDS for SQL Server with Multi-AZ

Answer

Amazon Redshift with concurrency scaling

Question 11

A healthcare company must store patient records in a relational database. Regulations require that the data be encrypted at rest using keys managed by the company, with automatic key rotation and audit trails of key usage. The database must support multi-AZ high availability and automated backups. Which AWS service and configuration should be used?

Accepted Answer

Amazon RDS for PostgreSQL with AWS KMS customer managed keys and Multi-AZ deployment. RDS for PostgreSQL with customer managed KMS keys and Multi-AZ deployment satisfies all stated requirements: relational storage, customer-controlled encryption with rotation and audit trails, high availability, and automated backups. The other options either use AWS managed keys that lack the required control or choose a non-relational service.

Answer

Amazon RDS for MySQL with default AWS managed keys and a read replica

Answer

Amazon Aurora MySQL with server-side encryption using an AWS managed key and Aurora Replicas

Answer

Amazon DynamoDB with AWS managed keys and global tables

Question 12

A company is deploying a new Amazon Aurora MySQL database cluster in a production environment. The database must be highly available and able to survive an Availability Zone (AZ) failure with minimal downtime. The company also wants to ensure that read traffic is distributed across multiple reader instances to improve performance. Which configuration should be implemented?

Accepted Answer

Deploy an Aurora MySQL cluster with one writer instance and multiple reader instances across multiple AZs, and use the reader endpoint to distribute read traffic.. Aurora MySQL stores data redundantly across three AZs and allows up to 15 read replicas. The writer endpoint handles write operations, while the reader endpoint automatically load-balances read connections across all reader instances. Placing readers in different AZs ensures that if the writer's AZ fails, Aurora can promote a reader in another AZ to become the new writer, typically within 30 seconds. This design meets both high availability and read scaling requirements.

Answer

Deploy an Aurora MySQL cluster with one writer instance and one reader instance in different AZs, and use a custom endpoint to distribute read traffic.

Answer

Deploy an Aurora MySQL cluster with multiple writer instances across multiple AZs and use a custom endpoint for writes.

Answer

Deploy a single Aurora MySQL instance in one AZ and enable automatic backups.

Question 13

A company uses Amazon Redshift for its data warehouse. The security team wants to ensure that all data in the cluster is encrypted at rest using a customer-managed key (CMK) from AWS KMS. They also need to ensure that the cluster's snapshots are encrypted with the same key. Which action should they take?

Accepted Answer

Create a new Redshift cluster with encryption enabled using the CMK, and migrate the data from the existing cluster.. Redshift encryption at rest must be enabled when the cluster is created. To encrypt an existing unencrypted cluster, you must create a new encrypted cluster with the CMK and migrate data. Snapshots of an encrypted cluster are automatically encrypted with the same key. Modifying an existing cluster to enable encryption is not supported.

Answer

Use AWS KMS to create a CMK, then attach it to the existing Redshift cluster via the AWS Management Console.

Answer

Enable encryption on the existing Redshift cluster using the CMK and set the snapshot encryption to use the same key.

Answer

Modify the existing cluster to use the CMK for encryption and then take a snapshot; the snapshot will automatically be encrypted with the same key.

Question 14

A database specialist is monitoring an Amazon RDS for SQL Server DB instance. The instance is experiencing intermittent connection timeouts. The specialist suspects that the issue is related to the maximum number of worker threads or the number of user connections. Which two metrics should the specialist review in Amazon CloudWatch to confirm the cause? (Choose two.)

Accepted Answer

DatabaseConnections. Connection timeouts in RDS for SQL Server can result from exhausting the maximum user connections or the maximum worker threads. DatabaseConnections shows current client connections, and Threads shows active threads. Together they indicate whether either limit is being approached. CPUUtilization and FreeableMemory are general health metrics, and UserConnections is not a valid RDS metric.

Answer

CPUUtilization

Answer

UserConnections

Answer

FreeableMemory

Question 15

A retail company runs an Amazon RDS for PostgreSQL database for its order management system. The database experiences predictable traffic spikes during flash sales, and the team wants reads to scale horizontally without changing the application's connection string. The application performs many read-only queries for product listings. What should a database specialist recommend?

Accepted Answer

Create one or more RDS read replicas and direct read-only queries to the reader endpoint.. Read replicas are the standard way to scale read-heavy workloads on RDS for PostgreSQL. They receive asynchronous replication from the primary and serve read-only queries, and the reader endpoint load-balances connections across them. Because applications connect to the reader endpoint rather than a specific replica, the connection string stays stable as replicas are added or removed during flash sales.

Answer

Increase the size of the primary RDS instance and enable storage autoscaling.

Answer

Migrate the database to Amazon DynamoDB and use eventually consistent reads for product listings.

Answer

Enable Multi-AZ for the RDS instance and point read-only queries at the standby instance.

Question 16

A company runs an Amazon RDS for SQL Server DB instance. The security team wants to ensure that all connections to the database are encrypted using SSL/TLS. They have already created a custom option group and added the SSL option. Which additional step is required to enforce SSL/TLS for all connections?

Accepted Answer

Modify the DB instance to set the Force SSL option to true in the SSL option settings.. For RDS for SQL Server, SSL/TLS encryption is enabled by adding the SSL option to the option group. To enforce that all connections use SSL, you must configure the option to set Force SSL to true. This setting makes the server reject unencrypted connections. Other parameters like rds.force_ssl are for different engines, and SQLNET parameters are for Oracle. Simply restarting the instance does not enforce SSL; the option must be configured correctly.

Answer

Create a new parameter group and set the SQLNET.SSL_VERSION parameter to 1.2.

Answer

Set the rds.force_ssl parameter to 1 in the parameter group associated with the DB instance.

Answer

Restart the DB instance to apply the SSL option.

Question 17

A media company stores user-uploaded video metadata in an Amazon DynamoDB table. Each item has a partition key of videoId and no sort key. The team needs to retrieve all videos uploaded by a specific user, ordered by upload timestamp, with a single query operation. Which design change should a database specialist make?

Accepted Answer

Add a global secondary index with userId as the partition key and uploadTimestamp as the sort key.. DynamoDB Query operations require the partition key and return items ordered by the sort key, so the access pattern is best served by a global secondary index keyed on userId with uploadTimestamp as the sort key. This preserves the base table's videoId key for point lookups while enabling efficient, sorted retrieval per user.

Answer

Create a local secondary index with userId as the sort key on the base table.

Answer

Change the base table's partition key to userId and add uploadTimestamp as the sort key.

Answer

Enable DynamoDB Streams and maintain a separate table keyed by userId.

Question 18

A financial services company is designing an Amazon DynamoDB table to store transaction records. The table must support efficient queries by customer ID and by transaction date, and the company wants to minimize the number of tables and avoid full table scans. The access patterns are: (1) retrieve all transactions for a given customer, sorted by date descending; (2) retrieve all transactions for a given date across all customers. Which TWO design choices should a database specialist make? (Choose two.)

Accepted Answer

Create a global secondary index (GSI) with partition key transaction_date and sort key customer_id.. To support retrieval of a customer's transactions sorted by date, the base table should use a composite key with customer_id as the partition key and transaction_date as the sort key. To support retrieval of all transactions for a given date, a global secondary index with transaction_date as the partition key and customer_id as the sort key provides an efficient, sorted query path. Together they cover both access patterns without full table scans.

Answer

Use a simple primary key with partition key transaction_id and create a GSI on customer_id.

Answer

Enable DynamoDB Streams to capture transaction records and query the stream for date-based access.

Answer

Create a local secondary index (LSI) with partition key customer_id and sort key transaction_date.

Question 19

A financial analytics team is designing an Amazon Redshift cluster for a data warehouse that ingests large volumes of structured data daily. The team wants to optimize query performance for complex joins and aggregations. Which TWO design choices should the team make to improve performance? (Choose two.)

Accepted Answer

Use a sort key on columns frequently used in WHERE clauses and range filters.. For Amazon Redshift, distribution keys and sort keys are primary design levers for query performance. A distribution key that aligns with join columns enables collocated joins, reducing network traffic. A sort key on filter columns allows zone map pruning, reducing I/O. Together, they optimize complex joins and aggregations. Concurrency scaling addresses concurrency, not single-query speed. Overly broad sort keys and ALL distribution for large tables introduce overhead and are not recommended.

Answer

Use a compound sort key with all columns in the table to maximize filtering.

Answer

Set the distribution style to ALL for large dimension tables to avoid joins.

Answer

Enable concurrency scaling to automatically add cluster capacity for read queries.

Question 20

An IoT company writes sensor readings to an Amazon Timestream table and also needs to run complex SQL joins between those readings and a relational asset registry hosted in Amazon Aurora PostgreSQL. The team wants to query both datasets from a single SQL endpoint without copying data into Aurora. Which AWS service should a database specialist recommend?

Accepted Answer

Amazon Athena with a federated connector to Timestream and a connector to Aurora PostgreSQL.. Amazon Athena federated query uses connectors to read from sources such as Timestream and Aurora PostgreSQL, allowing a single SQL query to join live data across them without ingestion. Glue ETL, Redshift Spectrum, and OpenSearch either copy data or lack the required cross-source SQL capability for this pattern.

Answer

Amazon OpenSearch Service with a Timestream integration and a JDBC plugin for Aurora.

Answer

Amazon Redshift Spectrum with external tables pointing at Aurora.

Answer

AWS Glue with a nightly extract, transform, and load job into Aurora.