DBS-C01 Management and Operations Practice Test 9 — 15 Questions

Question 1

A company is using Amazon DynamoDB with on-demand capacity for a serverless web application. The application experiences occasional throttling. The DynamoDB table has a simple primary key (partition key only). The throttled requests are related to a small number of partition keys. What is the MOST likely cause?

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

Accepted Answer

The partition key design leads to uneven access patterns, causing a hot partition.. Throttling on a few partition keys indicates a hot partition. Option A is wrong because on-demand capacity handles overall traffic, but partition-level limits still apply. Option C is wrong because a simple primary key is fine, but the data distribution is the issue. Option D is wrong because on-demand capacity automatically scales, but not per partition beyond the limit.

Answer

On-demand capacity has a per-partition throughput limit that is too low.

Answer

The table uses a composite primary key, which limits throughput.

Answer

The table's read/write capacity mode is set to provisioned instead of on-demand.

Question 2

A company is running an Amazon RDS for MySQL DB instance with Multi-AZ. The company wants to perform a major version upgrade with minimal downtime. Which TWO actions should be taken? (Choose TWO.)

Accepted Answer

Use the AWS Management Console to modify the DB instance and apply the upgrade immediately.. The correct answers are B and D. Option B: Using the AWS Management Console to modify the DB instance and apply the upgrade immediately is a valid method to perform a major version upgrade, though it will cause some downtime. Option D: Creating a read replica, upgrading it first, and promoting it minimizes downtime because the primary remains available during the upgrade. Option A is incorrect because the --allow-major-version-upgrade flag is used with the AWS CLI, but it must be combined with a modification; however, simply using the flag is not sufficient. Option C is incorrect because automatic minor version upgrades do not affect major version upgrades. Option E is incorrect because restoring a snapshot does not upgrade the engine version.

Answer

Use the AWS CLI to modify the DB instance with the --allow-major-version-upgrade flag.

Answer

Enable automatic minor version upgrades on the DB instance.

Answer

Take a snapshot and restore to the new version.

Question 3

A company is using Amazon DynamoDB with on-demand capacity for a serverless web application. The application experiences occasional throttling. The DynamoDB table has a simple primary key (partition key only). The throttled requests are related to a small number of partition keys. What is the MOST likely cause?

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

Accepted Answer

Use DynamoDB Accelerator (DAX) for write caching.. DAX can be used as a write-through cache for DynamoDB, reducing write latency by caching writes locally and asynchronously flushing to the primary table. Option B is correct because writing to the local region (e.g., us-east-1) and allowing global tables replication to eu-west-1 reduces the latency for the local write operation; the replication happens asynchronously. Option C is incorrect because strongly consistent reads do not affect write operations. Option D is incorrect because using a single-region table in eu-west-1 would eliminate the multi-region capability and manual replication adds complexity and potential latency. Option E is incorrect because increasing write capacity does not reduce latency; it increases throughput but not speed.

Answer

Use strongly consistent reads in the application.

Answer

Use a single-region table in eu-west-1 and replicate data manually.

Answer

Increase the write capacity of the table in eu-west-1.

Question 4

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. During the migration, they need to ensure minimal downtime. Which AWS service should be used for the migration?

Accepted Answer

AWS Database Migration Service. AWS Database Migration Service (DMS) is the correct choice because it is specifically designed for migrating databases to AWS with minimal downtime. DMS supports homogeneous migrations (e.g., Oracle to Oracle) and heterogeneous migrations (e.g., Oracle to Amazon Aurora), and it can perform continuous replication using change data capture (CDC) to keep the source and target databases synchronized during the migration, allowing you to cut over with only a brief pause.

Answer

AWS DataSync

Answer

Amazon S3 Transfer Acceleration

Answer

AWS Server Migration Service

Question 5

A database administrator notices that an Amazon Aurora MySQL DB cluster's primary instance is experiencing high CPU utilization due to a long-running analytical query. The application can tolerate eventual consistency. What is the MOST cost-effective solution to reduce CPU load on the primary instance?

Accepted Answer

Configure an Auto Scaling policy for Aurora Replicas and modify the application to use the reader endpoint.. Offloading read queries to Aurora Replicas is cost-effective and reduces primary load without additional infrastructure.

Answer

Create a read replica in a different region and route read traffic there.

Answer

Increase the instance size of the primary instance.

Answer

Enable Aurora Parallel Query on the cluster.

Question 6

A company uses Amazon RDS for PostgreSQL with Multi-AZ deployment. They experience increased write latency during peak hours. The DB instance size is db.r5.large. Which action would MOST effectively reduce write latency?

Accepted Answer

Disable the Multi-AZ feature and use asynchronous replication with a read replica for failover.. Multi-AZ deployments maintain a synchronous standby replica, which adds write latency because the primary must wait for the standby to acknowledge writes. Disabling Multi-AZ and using asynchronous replication to a read replica eliminates this synchronous overhead, allowing writes to complete faster. Option A increases instance size but doesn't address synchronous replication overhead; option C (synchronous_commit off) risks data loss and is not recommended; option D adds another standby, increasing overhead.

Answer

Switch to a db.r5.xlarge instance type.

Answer

Enable the synchronous_commit parameter to 'off'.

Answer

Enable Multi-AZ with two standby replicas.

Question 7

A company wants to automate the creation of a new Amazon RDS for SQL Server instance with specific configurations, including VPC, subnet, and security group settings. Which AWS service should be used to deploy this infrastructure as code?

Accepted Answer

AWS CloudFormation. AWS CloudFormation is the correct service because it allows you to define your entire infrastructure, including Amazon RDS for SQL Server instances, VPCs, subnets, and security groups, as code using a JSON or YAML template. This enables automated, repeatable deployments and version control of your infrastructure, which is the core requirement for infrastructure as code (IaC).

Answer

AWS CodeDeploy

Answer

AWS Elastic Beanstalk

Answer

AWS OpsWorks

Question 8

A company runs an Amazon DynamoDB table with on-demand capacity. They notice that a specific partition key receives a high volume of read requests, causing throttling for that partition. What is the BEST solution to distribute the load evenly?

Accepted Answer

Add a random suffix to the partition key values to increase partition cardinality.. Adding a suffix to the partition key to create multiple partitions distributes read load across partitions.

Answer

Create a global secondary index with a different partition key.

Answer

Use DynamoDB Accelerator (DAX) to cache reads.

Answer

Switch the table to provisioned capacity with auto-scaling.

Question 9

A company uses Amazon RDS for MySQL with read replicas. The application writes to the primary and reads from the replicas. Occasionally, the application reads stale data from the replicas. Which action would ensure read-after-write consistency without impacting write performance?

Accepted Answer

Configure the application to read from the primary instance for critical queries.. Using the primary instance for reads that require consistency ensures the application reads the latest data. Session-level replication checks are not supported in standard MySQL.

Answer

Set the replica_read_consistency parameter to 'session'.

Answer

Use the reader endpoint and increase the replica lag threshold.

Answer

Enable the 'rds_set_replication_status' parameter on the read replicas.

Question 10

Which TWO AWS services can be used to monitor and set alarms on Amazon RDS database performance metrics? (Choose two.)

Accepted Answer

Amazon RDS Enhanced Monitoring. CloudWatch monitors metrics and can set alarms; Enhanced Monitoring provides OS-level metrics. RDS Performance Insights is for performance analysis, not alarms.

Answer

Amazon RDS Performance Insights

Answer

AWS Trusted Advisor

Answer

AWS CloudTrail

Question 11

Which THREE actions can be performed using the AWS CLI for Amazon Aurora? (Choose three.)

Accepted Answer

Create a DB cluster from a snapshot using 'aws rds restore-db-cluster-from-snapshot'. All three are valid AWS CLI actions for Aurora. RestoreDBClusterFromS3 is for MySQL, but it exists.

Answer

Change the storage type of an Aurora cluster using 'aws rds modify-db-instance'

Answer

Enable auto-scaling for Aurora Replicas using 'aws rds enable-autoscaling'

Question 12

Which THREE factors should be considered when choosing between Amazon DynamoDB and Amazon RDS for a new application? (Choose three.)

Accepted Answer

Need for ACID transactions across multiple rows. Amazon RDS supports ACID transactions across multiple rows using traditional SQL databases like MySQL or PostgreSQL, which is essential for applications requiring strict consistency (e.g., financial systems). Amazon DynamoDB, while supporting ACID transactions via the TransactGetItems and TransactWriteItems APIs, is optimized for single-item or limited multi-item operations and may not perform as well for complex multi-row transactional workloads. The need for ACID across multiple rows is a key differentiator favoring RDS.

Answer

Need for automatic failover in multiple AWS Regions

Answer

Data size exceeding 10 TB

Question 13

A company wants to ensure that their Amazon RDS for PostgreSQL database is automatically backed up every day and retains backups for 30 days. Which configuration should they use?

Accepted Answer

Enable automated backups with a retention period of 30 days.. Automated backups are enabled by default with a retention period of 1-35 days. Setting backup retention period to 30 days meets the requirement.

Answer

Set the backup retention period to 0 to disable automated backups and use manual snapshots.

Answer

Create a manual snapshot daily using AWS Backup.

Answer

Enable Multi-AZ deployment for automatic failover.

Question 14

A company is running a production Amazon RDS for MySQL Multi-AZ DB instance. The database experiences intermittent high latency and the CloudWatch 'ReadLatency' metric spikes during periods of heavy read traffic. The application uses a single database endpoint. What is the MOST effective way to reduce read latency without changing the application code?

Accepted Answer

Enable a Multi-AZ deployment with one or more readable standby replicas.. Enabling a Multi-AZ deployment with one or more readable standby replicas allows you to offload read traffic to the standby instances using the Read Replica endpoint, reducing load on the primary and lowering ReadLatency. Since the application uses a single database endpoint, you can use Amazon RDS's built-in reader endpoint (for a Multi-AZ DB cluster) or configure a custom DNS to distribute reads, without modifying application code. This directly addresses the intermittent high latency during heavy read traffic by scaling read capacity horizontally.

Answer

Implement database sharding across multiple RDS instances.

Answer

Enable Multi-AZ on the existing DB instance to provide a standby for failover.

Answer

Increase the DB instance class to a larger size.

Question 15

A company uses Amazon DynamoDB with on-demand capacity for a gaming leaderboard. During a promotional event, write traffic spikes 10x, causing occasional 'ProvisionedThroughputExceededException' errors. The application retries with exponential backoff, but latency increases. The team notices that the 'ThrottledWriteRequests' metric spikes. What is the MOST cost-effective solution to handle these unpredictable spikes?

Accepted Answer

Switch to provisioned capacity with auto scaling configured for the expected peak.. The scenario describes a DynamoDB table using on-demand capacity but experiencing 'ProvisionedThroughputExceededException', which is an error specific to provisioned capacity. This inconsistency suggests the table is actually using provisioned capacity. Therefore, the best solution is to switch to provisioned capacity with auto scaling properly configured to handle the peak traffic, ensuring cost-effectiveness by scaling only when needed. Option A is invalid because on-demand tables do not throw this error. Option B (DAX) addresses read latency, not write throttling. Option D (SQS) adds complexity and latency and is not the most cost-effective for unpredictable write spikes.

Answer

Continue using on-demand capacity but ensure the table has no throttling.

Answer

Implement DynamoDB Accelerator (DAX) to reduce read load.

Answer

Use an Amazon SQS queue to buffer write requests before DynamoDB.