DBS-C01 Multiple Select — 40 Questions

Question 1

A company is using Amazon DynamoDB with on-demand capacity mode. The application experiences occasional throttling during traffic spikes. The database administrator wants to implement a solution to reduce throttling. Which THREE actions should the administrator take? (Choose THREE.)

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

Accepted Answer

Use DynamoDB Accelerator (DAX) to cache frequently accessed items.. Options A, D, and E are correct. Using DynamoDB Accelerator (DAX) caches frequently accessed items, offloading read capacity from the table and reducing read throttling. Implementing exponential backoff and retry logic in the application (option D) and designing the application to handle throttling by retrying with backoff (option E) both ensure that requests are retried gracefully during spikes, reducing the impact of throttling. Option B is incorrect because auto scaling is not applicable to on-demand capacity mode, which scales automatically. Option C is incorrect because switching to provisioned capacity does not inherently reduce throttling; on-demand already handles sudden spikes, but throttling may still occur if the workload exceeds table limits momentarily.

Answer

Enable auto scaling for the table.

Answer

Switch the table to provisioned capacity mode with auto scaling.

Question 2

Which TWO AWS services can be used together to migrate an on-premises MySQL database to Amazon Aurora MySQL with minimal downtime? (Select TWO.)

Accepted Answer

AWS Schema Conversion Tool (SCT). AWS Database Migration Service (DMS) can perform continuous replication from an on-premises MySQL source to an Amazon Aurora MySQL target using change data capture (CDC), enabling near-zero downtime. The AWS Schema Conversion Tool (SCT) is used to assess and convert the source schema, including any incompatible objects, to ensure the Aurora target is ready for migration. Together, SCT handles schema transformation while DMS handles the ongoing data replication.

Answer

Amazon Route 53

Answer

AWS CloudFormation

Answer

AWS Global Accelerator

Question 3

Which TWO of the following are advantages of using Amazon Aurora over standard RDS for MySQL?

Accepted Answer

Aurora can deliver up to 5x the throughput of standard MySQL on the same hardware.. Amazon Aurora uses a distributed, SSD-backed storage subsystem that separates compute from storage, enabling it to deliver up to 5x the throughput of standard MySQL running on the same hardware. This performance gain comes from the Aurora storage engine's ability to reduce I/O operations and parallelize writes across multiple storage nodes.

Answer

Aurora automatically fails over to a read replica in case of primary failure.

Answer

Aurora is compatible with PostgreSQL, so you can migrate from SQL Server easily.

Answer

Aurora supports up to 15 read replicas, while RDS for MySQL only supports 5.

Question 4

A company runs a web application on Amazon EC2 instances behind an Application Load Balancer. The application uses Amazon RDS for MySQL. Recently, the database CPU utilization spikes to 100% during peak hours. The team observes that the spike is caused by a large number of slow queries. They need to identify and resolve the issue with minimal disruption. Which combination of steps should they take? (Choose two.)

Accepted Answer

Enable RDS Performance Insights to identify the slow queries. The correct combination is A and D. Option A: Enabling RDS Performance Insights quickly identifies slow queries and their resource consumption, pinpointing the cause of CPU spikes. Option D: Creating a read replica and directing reporting queries to it offloads read traffic from the primary instance, reducing CPU load during peak hours. Option B is not an identification step and may not address the root cause, while also incurring unnecessary cost. Option C addresses I/O bottlenecks, not CPU spikes from slow queries. Option E helps with connection management but does not identify or directly resolve the slow query issue.

Answer

Upgrade to a larger instance type

Answer

Increase the DB instance storage to improve I/O

Answer

Implement connection pooling using Amazon RDS Proxy

Question 5

Which THREE design patterns are commonly used to optimize DynamoDB performance for write-heavy workloads?

Accepted Answer

Using DynamoDB adaptive capacity to handle unbalanced access patterns.. DynamoDB adaptive capacity automatically isolates heavily accessed partitions, allowing them to consume more throughput without throttling other partitions. This is critical for write-heavy workloads with uneven access patterns, as it prevents hot partitions from degrading overall performance.

Answer

Using sparse indexes on rarely accessed attributes.

Answer

Using global tables to distribute writes across regions.

Question 6

A company is migrating a 500 GB PostgreSQL database from on-premises to Amazon Aurora PostgreSQL. They need to minimize downtime and ensure that all data changes made during migration are synchronized. Which three components are required for this migration? (Choose THREE.)

Accepted Answer

AWS Database Migration Service (DMS) replication instance. AWS DMS replication instance is required because it orchestrates the continuous replication of data from the source PostgreSQL database to the target Aurora PostgreSQL cluster. It manages the connection, reads changes from the source using logical replication slots, and applies them to the target, enabling near-zero downtime migration.

Answer

AWS Schema Conversion Tool (SCT)

Answer

AWS VPN connection between on-premises and AWS

Question 7

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

Accepted Answer

Modify the DB instance to enable automatic minor version upgrade.. Enabling automatic minor version upgrades on an RDS for MySQL Multi-AZ instance allows Amazon RDS to apply the upgrade during the next maintenance window with minimal downtime. During the upgrade, RDS patches the standby first, then performs a failover to make the standby the new primary, resulting in a brief (typically under 60 seconds) interruption rather than a full outage. This approach leverages the Multi-AZ architecture to reduce downtime compared to manual upgrades.

Answer

Create a read replica, upgrade the replica, and promote it.

Answer

Modify the DB instance to be a Single-AZ deployment to simplify the upgrade.

Answer

Stop the DB instance before applying the upgrade.

Question 8

Which TWO of the following are benefits of using Amazon RDS Proxy? (Choose TWO.)

Accepted Answer

Reduces the number of database connections by pooling them.. Amazon RDS Proxy acts as a connection broker between your application and the database, maintaining a pool of established connections. When the application opens a new connection, RDS Proxy reuses an idle connection from the pool, which reduces the total number of database connections and prevents the database from being overwhelmed. This pooling mechanism directly addresses the issue of connection exhaustion, especially in serverless or highly concurrent environments.

Answer

Automatically encrypts all traffic between the application and the database.

Answer

Provides built-in read/write splitting for read replicas.

Answer

Reduces storage costs by compressing data in transit.

Question 9

A company's Amazon Aurora MySQL DB cluster is experiencing a failover event. Which THREE metrics in CloudWatch should be examined to understand the cause of the failover?

Accepted Answer

ACUUtilization. (ACUUtilization) is correct because high ACU utilization can indicate resource exhaustion (CPU/memory pressure) that may trigger a failover in Aurora. Option D (DatabaseConnections) is correct because a sudden spike or drop in connections could signal issues like connection exhaustion or application failures that lead to failover. Option E (FailoverCount) is correct because this metric directly tracks the number of failover events; examining the timestamp of the last increment helps correlate with the incident. Option B (ReadLatency) is wrong because while high read latency can be a symptom, it is not a direct cause of failover; Aurora uses different mechanisms for read scaling. Option C (BinLogDiskUsage) is wrong because it relates to binary log storage for replication, not a direct trigger for failover.

Answer

ReadLatency

Answer

BinLogDiskUsage

Question 10

A company is building a real-time leaderboard for an online game using Amazon DynamoDB. The leaderboard must update scores within seconds and support queries for top 100 players. Which TWO design patterns should be used? (Choose TWO.)

Accepted Answer

Use DynamoDB Streams to trigger a Lambda function that updates a separate leaderboard table.. DynamoDB Streams can capture score updates in near real-time and trigger a Lambda function to maintain a separate leaderboard table optimized for top-100 queries. This decouples the write-heavy game table from the read-heavy leaderboard, ensuring low-latency updates without contention.

Answer

Create a global secondary index on the score attribute for efficient range queries.

Answer

Store the leaderboard in Amazon ElastiCache for Redis for low-latency reads.

Answer

Set the sort key to the score attribute for natural ordering.

Question 11

A company is using Amazon RDS for MySQL and has enabled Enhanced Monitoring. The database administrator wants to identify the top contributors to disk I/O. Which THREE metrics from Enhanced Monitoring should they examine?

Accepted Answer

DirtyBufferFlushRate. (DirtyBufferFlushRate) is correct because it indicates the rate at which dirty (modified) buffers are flushed from memory to disk, directly contributing to disk writes and I/O. Option D (WriteOps) is correct as it measures the number of write operations performed on disk, a direct contributor to disk I/O. Option E (PhysicalReads) is correct because it represents read operations that actually hit the disk (i.e., cache misses), contributing to disk I/O. Options B (NetworkThroughput) and C (LogicalReads) are incorrect: NetworkThroughput relates to network traffic, not disk I/O; LogicalReads are reads satisfied from the buffer pool (memory), not disk.

Answer

NetworkThroughput

Answer

LogicalReads

Question 12

A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. They need to minimize downtime and ensure data consistency. Which TWO methods can be used together to achieve this?

Accepted Answer

Use AWS DMS with full load and CDC. AWS DMS with full load and Change Data Capture (CDC) enables a zero-downtime migration by first copying the existing data (full load) and then continuously replicating ongoing changes from the on-premises PostgreSQL source to the Amazon RDS for PostgreSQL target. This ensures data consistency because CDC captures transactions in near real-time using the PostgreSQL logical replication slot mechanism, allowing the target to stay synchronized until the cutover.

Answer

Take a file system snapshot and copy to Amazon EBS

Answer

Use pg_dump and pg_restore

Answer

Export data to Amazon S3 and import using COPY

Question 13

Which THREE factors should be considered when choosing between a homogeneous migration and a heterogeneous migration to Amazon RDS? (Select THREE.)

Accepted Answer

Performance requirements of the target database.. A homogeneous migration (e.g., MySQL to RDS MySQL) typically requires minimal schema changes, preserves performance characteristics, and maintains existing licensing costs. A heterogeneous migration (e.g., Oracle to RDS PostgreSQL) requires schema conversion (validating schema compatibility), may require re-architecting to meet performance requirements due to different query optimizers, and can change licensing costs (e.g., eliminating Oracle licenses). Therefore, factors B, D, and E directly influence the choice between homogeneous and heterogeneous migrations.

Answer

Network latency between source and target.

Answer

Amount of application code changes needed.

Question 14

Which TWO of the following are recommended best practices for designing a relational database on Amazon RDS? (Select TWO.)

Accepted Answer

Use read replicas to scale read-heavy workloads. Amazon RDS read replicas offload read traffic from the primary DB instance, improving performance for read-heavy workloads by providing additional read-only endpoints. This is a core best practice for scaling read capacity without increasing load on the source instance.

Answer

Use LOB data types to store large text fields

Answer

Use non-EBS-optimized instances to reduce costs

Answer

Store large binary objects (BLOBs) in the database

Question 15

A company uses Amazon RDS for PostgreSQL with Multi-AZ. The primary instance fails and a failover occurs. After failover, the application reports elevated write latency. Which TWO are possible causes?

Accepted Answer

The buffer pool is not warm on the new primary. After a Multi-AZ failover, the new primary instance starts with a cold buffer pool (no cached data blocks). PostgreSQL relies on shared buffers to cache frequently accessed data; without a warm cache, every read request must fetch data from disk, which increases I/O and write latency because writes often require reading the affected pages first. This is a known behavior in RDS for PostgreSQL after failover, and it resolves as the buffer pool warms up over time.

Answer

A read replica is now promoting to primary

Answer

The new primary has a smaller instance size

Answer

Automated backups are running on the new primary

Question 16

Which TWO database services are most suitable for workloads that require ACID transactions?

Accepted Answer

Amazon Aurora. Amazon Aurora is correct because it is a MySQL- and PostgreSQL-compatible relational database engine that provides full ACID (Atomicity, Consistency, Isolation, Durability) transaction support, including multi-statement transactions with commit and rollback. Aurora uses a distributed, fault-tolerant storage subsystem that replicates data across three Availability Zones, ensuring durability and consistency for transactional workloads.

Answer

Amazon Neptune

Answer

Amazon Timestream

Answer

Amazon DynamoDB

Question 17

A company is experiencing slow query performance on an Amazon RDS for MySQL database. The DBA wants to identify the most time-consuming queries. Which TWO actions should the DBA take? (Choose two.)

Accepted Answer

Use Amazon RDS Performance Insights.. Amazon RDS Performance Insights (Option D) provides a database performance tuning and monitoring feature that visualizes database load and identifies the most time-consuming queries by breaking down wait events, SQL statements, and hosts. It directly helps the DBA pinpoint the specific queries causing performance degradation without additional configuration or overhead.

Answer

Enable the audit log.

Answer

Enable the general log and review it.

Answer

Use Amazon RDS Enhanced Monitoring.

Question 18

Which TWO factors should you consider when choosing between Amazon RDS and Amazon DynamoDB for a new application?

Accepted Answer

RDS requires a predefined schema, while DynamoDB is schema-less.. Amazon RDS (relational database service) requires a predefined schema with tables, columns, and data types before data can be inserted, enforcing ACID compliance and referential integrity. In contrast, Amazon DynamoDB is a NoSQL key-value and document database that is schema-less, allowing you to store items with varying attributes without upfront schema definition, which is ideal for agile development and unstructured data.

Answer

DynamoDB can only be accessed from within a VPC, while RDS can be public.

Answer

Only RDS supports Multi-AZ deployments for high availability.

Answer

Both services support encryption at rest and in transit.

Question 19

A company runs a MySQL-compatible database on Amazon RDS for a mission-critical application. The database experiences high write latency due to frequent index updates. The team wants to redesign the database to reduce write amplification and improve insert performance. Which TWO design changes could help?

Accepted Answer

Use batch INSERT statements instead of single-row inserts. Batch INSERT statements reduce the overhead of per-row index updates by combining multiple rows into a single transaction. This minimizes the number of index tree traversals and log flushes, directly lowering write amplification and improving insert throughput in InnoDB.

Answer

Switch the storage engine from InnoDB to MyISAM

Answer

Upgrade to a larger RDS instance class

Answer

Normalize the database schema to reduce data redundancy

Question 20

A company is planning to migrate a 1 TB MySQL database from on-premises to Amazon RDS for MySQL. The migration must have minimal downtime and support ongoing replication. Which THREE steps should the company include in the migration plan? (Choose THREE.)

Accepted Answer

Set up an AWS Direct Connect or VPN connection between on-premises and AWS.. A stable, low-latency network connection (Direct Connect or VPN) is essential for AWS DMS to perform ongoing replication with minimal downtime. Without this, the replication can be interrupted by network issues, causing data loss or extended cutover windows.

Answer

Deploy an Amazon EC2 instance to act as a proxy for the DMS replication.

Answer

Install the AWS Schema Conversion Tool on the source server to convert the schema.