DBS-C01 Practice Test 13 — 15 Questions

Question 1

Refer to the exhibit. An application on an EC2 instance is trying to read an object from the S3 bucket 'data-lake-prod'. The instance is in a VPC with an IP address of 10.0.1.5. The application receives an Access Denied error. What is the cause?

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

Accepted Answer

A Deny statement with a source IP condition is blocking access.. The Deny statement applies to the source IP 10.0.1.5 (within 10.0.0.0/8), overriding the Allow. Option A is wrong because the IAM role does allow s3:GetObject on the bucket. Option C is wrong because there is no explicit condition on the Allow statement. Option D is wrong because the policy is attached to the role, not an SCP.

Answer

An SCP is denying S3 access to the account.

Answer

The S3 bucket policy requires a specific VPC endpoint.

Answer

The IAM role does not have permission to read from the bucket.

Question 2

A company is migrating a 3 TB SQL Server database to Amazon RDS for SQL Server. The migration must be completed with less than 15 minutes of downtime. The company has set up AWS DMS with ongoing replication. During the final cutover, the DMS task fails with a 'Target error: Cannot insert duplicate key' error. What is the most likely cause?

Accepted Answer

The target table has an identity column that is not set to allow insert of explicit values.. The error 'Cannot insert duplicate key' during DMS full load or ongoing replication indicates that the target table has an identity column that does not allow explicit value insertion. By default, SQL Server identity columns are set to NOT FOR REPLICATION = OFF, meaning DMS cannot insert rows with explicit identity values, causing duplicate key violations when the source has identity values that conflict with the target's auto-generated sequence. To resolve this, you must set the identity column to allow explicit inserts (e.g., SET IDENTITY_INSERT ON) or configure DMS to use 'Do nothing' for identity handling.

Answer

The DMS task is not set to truncate the target before loading.

Answer

The source database transaction log is full.

Answer

The source database has a primary key violation.

Question 3

A company is using Amazon DynamoDB with provisioned capacity. They notice an increase in throttled write requests. The workload consists of writes to a single partition key. Which TWO actions would help reduce throttling?

Accepted Answer

Increase the provisioned write capacity units.. Options B and C are correct. Increasing provisioned write capacity (B) directly addresses throttling by allowing more writes per second. Enabling DynamoDB auto scaling with adaptive capacity (C) automatically adjusts capacity based on traffic and helps handle uneven access patterns, including hot partitions. Option A (adding a global secondary index with a different partition key) does not reduce throttling on the base table; it only provides an alternative query path. Option D (DAX) is a read cache and does not assist with write throttling. Option E (write sharding) can help distribute writes across partitions, but the question asks for two actions from the given list; B and C are the most direct and effective.

Answer

Add a global secondary index with a different partition key.

Answer

Use DynamoDB Accelerator (DAX) for write caching.

Answer

Implement write sharding by adding a suffix to the partition key.

Question 4

A company wants to run a MongoDB-compatible database on AWS with automated patching and backups. Which service should they choose?

Accepted Answer

Amazon DocumentDB (with MongoDB compatibility). Amazon DocumentDB with MongoDB compatibility is the correct choice because it is a fully managed, MongoDB-compatible database service that provides automated patching and backups. It supports the MongoDB wire protocol and drivers, allowing existing MongoDB applications to migrate with minimal changes while offloading administrative tasks like patching, backup, and replication to AWS.

Answer

Self-managed MongoDB on Amazon EC2

Answer

Amazon DynamoDB

Answer

Amazon RDS for MySQL

Question 5

A company is deploying a new application that requires a MySQL-compatible database with automatic scaling of compute and storage resources. Which AWS service should be used?

Accepted Answer

Amazon Aurora MySQL. Amazon Aurora MySQL is the correct choice because it is a MySQL-compatible relational database that automatically scales compute (up to 128 vCPUs and 244 GiB of memory) and storage (up to 128 TiB in 10 GiB increments) without downtime. Aurora's storage subsystem is distributed and self-healing, scaling as data grows, and its compute can be scaled via Auto Scaling policies or by modifying the instance class with minimal disruption.

Answer

Amazon RDS for MySQL

Answer

Amazon DynamoDB

Answer

Amazon Redshift

Question 6

A company wants to ensure that only specific IAM users can perform certain operations on an Amazon RDS DB instance, such as creating snapshots or modifying the instance. Which AWS feature should be used to define these permissions?

Accepted Answer

IAM policies. IAM policies are used to grant or deny permissions to AWS resources, including Amazon RDS DB instances. By attaching an IAM policy to a user, group, or role, you can control which actions (e.g., CreateDBSnapshot, ModifyDBInstance) are allowed. Options A, C, and D are incorrect: VPC security groups control network traffic, DB parameter groups manage database engine settings, and DB subnet groups define which subnets the DB instance can use—none of these define permissions for specific operations.

Answer

VPC security groups

Answer

DB parameter groups

Answer

DB subnet groups

Question 7

A company is using Amazon DynamoDB to store IoT sensor data. The application writes a large volume of data and needs to read recent data by timestamp. The table has a partition key of device_id and a sort key of timestamp. The access pattern is to read the latest data for a specific device. Which TWO design patterns will optimize read performance and reduce costs?

Accepted Answer

Use adaptive capacity to evenly distribute traffic across partitions.. Adaptive capacity allows DynamoDB to automatically manage partition traffic distribution, preventing hot partitions when a single device_id receives a high volume of writes. This ensures consistent read performance without manual partition management. Option B is correct because DAX provides an in-memory cache for the most frequently accessed data, reducing read latency and read capacity unit consumption for repeated queries of recent sensor data.

Answer

Enable auto scaling for the table to handle spikes.

Answer

Use DynamoDB Transactions for consistent reads.

Answer

Create a global secondary index (GSI) with device_id as partition key and timestamp as sort key.

Question 8

A company is deploying a new Amazon RDS for Oracle instance and needs to ensure high availability and automatic failover. Which configuration should be used?

Accepted Answer

Multi-AZ deployment. (Multi-AZ deployment) is correct because it provisions a synchronous standby replica in a different Availability Zone, enabling automatic failover without data loss when the primary instance fails. This meets the high availability and automatic failover requirements for Amazon RDS for Oracle. Option D (Automated backups with point-in-time recovery) provides backup and recovery capabilities but does not ensure high availability or automatic failover; it is not a configuration for automatic failover.

Answer

Read Replicas in a different Region

Answer

Enhanced Monitoring

Answer

Automated backups with point-in-time recovery

Answer

Deletion protection

Question 9

A company is using Amazon Redshift and needs to encrypt data at rest with a customer-managed key. Which TWO steps are required to enable encryption with a customer-managed AWS KMS key?

Accepted Answer

Create a customer-managed key in AWS KMS.. Options A and B are correct. To enable encryption with a customer-managed AWS KMS key, you must first create a customer-managed KMS key (A) and then specify that KMS key when creating a new Redshift cluster (B). Option C is incorrect because you cannot modify an existing unencrypted Redshift cluster to enable encryption; encryption must be set at cluster creation or by restoring from an encrypted snapshot. Option D is incorrect because Redshift encryption with KMS does not require an HSM. Option E is incorrect because AWS Support cannot enable encryption; it must be performed by the customer via the AWS Management Console, CLI, or API.

Answer

Use the AWS CLI to modify the cluster to enable encryption.

Answer

Configure the Redshift cluster to use an HSM.

Answer

Request AWS Support to enable encryption.

Question 10

A company is using Amazon DynamoDB with auto scaling enabled. The table's read capacity is set to a minimum of 100 and maximum of 1000 read capacity units (RCUs). The actual consumed read capacity is consistently at 200 RCUs. What should the database specialist do to optimize costs without impacting performance?

Accepted Answer

Lower the minimum read capacity to 200 RCUs.. Lowering the minimum read capacity to 200 RCUs matches the actual consumption, preventing over-provisioning when auto scaling scales down. This reduces costs without affecting performance, as the capacity remains sufficient for the consistent workload. Option A is incorrect because increasing the minimum would raise costs unnecessarily. Option C is incorrect because disabling auto scaling removes the ability to handle traffic spikes automatically. Option D is incorrect because decreasing the maximum could cause throttling during unexpected demand spikes.

Answer

Increase the minimum read capacity to 500 RCUs.

Answer

Disable auto scaling and set the read capacity to 200 RCUs.

Answer

Decrease the maximum read capacity to 500 RCUs.

Question 11

A company is migrating their on-premises Oracle database to Amazon RDS for Oracle. They need to ensure minimal downtime. During the migration, they observe that the change data capture (CDC) is falling behind. What is the most effective approach to catch up?

Accepted Answer

Increase the instance size of the target RDS instance. Increasing the instance size of the target RDS instance provides more CPU and memory resources for the CDC process, allowing it to process more changes per unit time and catch up on lag. Option A is incorrect because disabling supplemental logging on the source Oracle database would prevent the capture of necessary change data, breaking CDC entirely and preventing any catch-up. Option C is incorrect because pausing the CDC task would stop processing changes, allowing the lag to grow further, not catch up. Option D is incorrect because stopping CDC and performing a full load migration would cause significant downtime, which contradicts the requirement for minimal downtime.

Answer

Disable supplemental logging on the source

Answer

Pause the CDC task and resume later

Answer

Stop the CDC and perform a full load migration

Question 12

A company uses Amazon DynamoDB with on-demand capacity. Users report increased latency during peak hours. The application uses the DynamoDB API. Which monitoring metric should be examined first to identify throttling issues?

Accepted Answer

ThrottledRequests. (ThrottledRequests). ThrottledRequests is a CloudWatch metric that directly indicates the number of requests that were throttled due to exceeding provisioned throughput limits or the instantaneous capacity of on-demand mode. For on-demand capacity, while DynamoDB scales automatically, sudden spikes can still cause throttling. Examining ThrottledRequests first provides the most direct indication of throttling issues. Option B (SuccessfulRequestLatency) is incorrect because it measures latency of successful requests, not throttling. Option C (ReadThrottleEvents) is incorrect because it only counts throttled read events, whereas ThrottledRequests includes both reads and writes. Option D (ConsumedWriteCapacityUnits) is incorrect because it shows the amount of write capacity consumed, not throttled requests.

Answer

SuccessfulRequestLatency

Answer

ReadThrottleEvents

Answer

ConsumedWriteCapacityUnits

Question 13

A company runs a MySQL database on Amazon RDS. They need to export a subset of data to Amazon S3 for analysis using Amazon Athena. The data is stored in multiple tables with complex joins. What is the MOST efficient way to export the data?

Accepted Answer

Use the SELECT INTO OUTFILE S3 extension to export the query results directly to S3.. Amazon RDS for MySQL supports the `SELECT INTO OUTFILE S3` extension, which allows you to export the results of complex queries (including joins) directly to Amazon S3 in a single, efficient operation. This avoids the overhead of intermediate staging or manual file transfers, making it the most efficient method for exporting a subset of data to S3 for Athena analysis.

Answer

Use the COPY command from Amazon Redshift to pull data from RDS.

Answer

Use the AWS Schema Conversion Tool (SCT) to extract the data to S3.

Answer

Use mysqldump to export the tables and then upload the files to S3.

Question 14

Which TWO AWS services can be used to migrate a MongoDB database to Amazon DocumentDB? (Choose 2.)

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS Database Migration Service (AWS DMS) supports MongoDB as a source and Amazon DocumentDB as a target, enabling continuous replication with change data capture (CDC) for minimal downtime. MongoDB native tools (mongodump and mongorestore) are also valid for offline, one-time migrations by exporting the database as BSON files and importing them directly into DocumentDB.

Answer

AWS DataSync

Answer

Amazon S3

Answer

Amazon Kinesis Data Streams

Question 15

A team is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The database is 2 TB and has a 6-hour maintenance window. Which AWS service should the team use to minimize downtime?

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS DMS is the correct choice because it can perform a live migration from Oracle to Aurora PostgreSQL with minimal downtime using ongoing replication (change data capture). It supports heterogeneous migrations, automatically converting the source schema and data types, and can handle a 2 TB database within the 6-hour maintenance window by using multiple parallel tasks and large instance types.

Answer

Amazon S3 Transfer Acceleration

Answer

AWS Snowball Edge

Answer

Amazon EC2 with Oracle installed