DBS-C01 Multiple Select — 10 Questions

Question 1

A company is designing a database for an IoT application that ingests sensor data from thousands of devices. Each device sends a reading every minute. The data includes device_id, timestamp, temperature, humidity, and pressure. The application needs to store this data and support queries that retrieve all readings for a specific device within a time range. The company expects high write throughput and moderate read frequency. The data must be stored with high durability. Which TWO database designs are appropriate for this workload? (Choose TWO.)

Accepted Answer

Use Amazon DynamoDB with device_id as partition key and timestamp as sort key.. Option C is correct because DynamoDB's partition key (device_id) and sort key (timestamp) design allows efficient retrieval of all readings for a specific device within a time range using a Query operation with a KeyConditionExpression on the sort key. This schema supports high write throughput by distributing writes across partitions based on device_id, and DynamoDB's multi-AZ replication provides high durability.

Answer

Use Amazon DynamoDB with device_id as partition key and store all readings for a device as a list attribute in a single item, updating the list every minute.

Answer

Use Amazon S3 to store compressed JSON files per device per hour, and query using Amazon Athena.

Answer

Use Amazon RDS for MySQL with a single table and index on device_id and timestamp.

Question 2

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB and has a high number of small transactions. The company needs to minimize downtime during the migration. Which TWO strategies should be used together? (Choose two.)

Accepted Answer

Use AWS Database Migration Service (DMS) to perform a full load and ongoing replication.. AWS DMS with ongoing replication (CDC) is the correct choice because it allows a full load of the 2 TB database followed by continuous replication of changes, minimizing downtime by keeping the target RDS instance nearly synchronized with the source until cutover. This approach is specifically designed for large databases with high transaction volumes, as it reduces the final outage window to seconds or minutes.

Answer

Use Oracle Data Pump to export the database and import into RDS.

Answer

Set up a VPN connection between on-premises and AWS for direct database link.

Answer

Create a manual snapshot of the RDS instance during the migration.

Question 3

A company is running a production Amazon DynamoDB table with on-demand capacity. The table experiences occasional throttling during traffic spikes. The table's partition key is a timestamp, and the workload is write-heavy. The operations team needs to reduce throttling. Which THREE actions should the team take? (Choose three.)

Accepted Answer

Add a random suffix to the partition key to distribute writes evenly.. Option A is correct because adding a random suffix to the timestamp partition key breaks the sequential write pattern, distributing writes evenly across all partitions. This prevents hot partitions, which are the root cause of throttling in a write-heavy workload with a monotonically increasing partition key.

Answer

Increase the read capacity units for the table.

Answer

Enable DynamoDB global tables to distribute write traffic.

Question 4

A company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database specialist needs to monitor the migration process and ensure data consistency. Which TWO AWS services should be used together to continuously monitor the replication lag and data integrity?

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS DMS is the correct service because it is specifically designed for database migrations and provides built-in monitoring of replication lag via the 'CDC latency' metric. Amazon CloudWatch is the correct complementary service because it collects and visualizes DMS metrics, including replication lag and task status, and can trigger alarms if data integrity or latency thresholds are breached.

Answer

Amazon RDS Performance Insights

Answer

AWS Schema Conversion Tool (AWS SCT)

Answer

AWS Glue

Question 5

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The security team requires that all data be encrypted at rest using a customer-managed KMS key. Additionally, the database should be accessible only from a specific VPC. Which THREE steps should the database specialist take to meet these requirements? (Choose three.)

Accepted Answer

Configure the security group for the RDS instance to allow inbound traffic only from the application security group.. Option A is correct because security groups act as a virtual firewall for RDS instances. By configuring the security group to allow inbound traffic only from the application security group, you restrict database access to specific application servers, meeting the requirement that the database be accessible only from a specific VPC.

Answer

Create a VPC endpoint for RDS and associate it with the DB instance.

Answer

Store the encryption key in Amazon S3 and configure RDS to use it.

Question 6

A company runs a production Amazon RDS for PostgreSQL DB instance. The database experiences intermittent high latency during peak hours. The company's monitoring shows that CPU utilization is below 40%, memory is adequate, and network throughput is normal. The DB instance uses General Purpose SSD (gp2) storage with 3,000 Provisioned IOPS. Which TWO actions should a database specialist take to diagnose and resolve the performance issue? (Choose two.)

Accepted Answer

Check the Burst Balance metric in Amazon CloudWatch for the DB instance.. Option A is correct because gp2 storage uses a credit-based burst model, and the Burst Balance metric indicates the remaining I/O credits. If the burst balance is depleted, the instance is throttled to the baseline IOPS (3,000 for this size), causing high latency despite low CPU and adequate memory. Checking this metric directly identifies whether the storage is starved for I/O credits.

Answer

Change the storage type to Provisioned IOPS SSD (io1) with 10,000 IOPS.

Answer

Increase the Read IOPS by modifying the instance to a larger instance class.

Answer

Review the SwapUsage metric for the DB instance to check for memory pressure.

Question 7

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The security team requires that all connections to the database be encrypted in transit. Which TWO steps should be taken to enforce this requirement?

Accepted Answer

Set the rds.force_ssl parameter to 1 in the DB parameter group.. Setting the rds.force_ssl parameter to 1 in the DB parameter group forces all connections to the Oracle RDS instance to use SSL/TLS encryption. This is the direct method to enforce encryption in transit for Amazon RDS for Oracle, as it rejects any non-SSL connections at the database level.

Answer

Enable Oracle native network encryption (NNE) in the sqlnet.ora file.

Answer

Use AWS Secrets Manager to store database credentials and enable Kerberos authentication.

Answer

Use AWS Direct Connect or a VPN to connect to the VPC.

Question 8

A company is running a critical application on Amazon DynamoDB. The table has a partition key of 'user_id' and a sort key of 'timestamp'. The application frequently queries for all items for a given user within a date range. The read capacity is often throttled during peak hours. Which THREE steps should the database specialist take to resolve the throttling?

Accepted Answer

Enable DynamoDB adaptive capacity to automatically adjust throughput. Option A is correct because DynamoDB adaptive capacity automatically manages throughput to accommodate uneven access patterns, such as when a single 'user_id' partition receives more reads than provisioned. It allows the table to absorb throttling by redistributing unused capacity from other partitions, which directly addresses the peak-hour throttling without manual intervention.

Answer

Change the partition key to 'timestamp' to improve read distribution

Answer

Decrease the provisioned write capacity units (WCU) to free up resources for reads

Question 9

A company is designing a multi-tenant SaaS application on Amazon Aurora MySQL. Each tenant has its own database, but some tenants are very large and generate high write traffic. The company wants to isolate tenant workloads to prevent a noisy neighbor from affecting other tenants. Which TWO design strategies should the database specialist recommend?

Accepted Answer

Use Aurora Serverless for tenants with variable workloads. Option A is correct because Aurora Serverless automatically scales compute capacity based on application demand, which is ideal for tenants with variable workloads. This prevents a noisy neighbor scenario by ensuring that a tenant's burst of write traffic does not consume shared resources that would degrade performance for other tenants.

Answer

Use a single Aurora cluster with read replicas for each tenant

Answer

Migrate all tenants to Amazon DynamoDB and use DynamoDB Accelerator (DAX) for caching

Answer

Use Amazon RDS Proxy to pool connections and limit throughput per tenant

Question 10

A company is using Amazon DynamoDB for a shopping cart application. The table has a partition key of `user_id` and a sort key of `item_id`. The application performs frequent updates to the `quantity` attribute. The company notices that write requests are being throttled during peak hours. Which TWO actions would help reduce throttling? (Choose two.)

Accepted Answer

Increase the provisioned write capacity for the table.. Option A is correct because increasing the provisioned write capacity directly raises the number of write capacity units (WCUs) available per second, allowing more write requests to succeed without being throttled. Since the application performs frequent updates to the `quantity` attribute, which consumes write capacity, adding more capacity alleviates throttling during peak hours.

Answer

Use conditional writes to prevent overwrites.

Answer

Enable DynamoDB Streams to process writes asynchronously.

Answer

Enable DynamoDB Accelerator (DAX) for the table.