Amazon DBS-C01 AWS Certified Database – Specialty (DBS-C01) Free Practice Test — 30 Questions

Question 1

In a multi-region database architecture, a company has implemented a failover mechanism to ensure high availability and disaster recovery. During a simulated failover event, the primary database in Region A becomes unavailable. The failover process is designed to redirect traffic to a standby database in Region B. If the primary database has a read latency of 20 ms and a write latency of 50 ms, while the standby database has a read latency of 30 ms and a write latency of 40 ms, what is the total latency experienced by an application that performs one read and one write operation during the failover process?

Accepted Answer

70 ms

Question 2

A retail company is designing a new database schema to manage its inventory and sales data. The company wants to ensure that the database can efficiently handle queries related to product sales, stock levels, and supplier information. They decide to implement a star schema for their data warehouse. In this context, which of the following best describes the primary advantage of using a star schema over a normalized schema for this scenario?

Accepted Answer

It simplifies complex queries by reducing the number of joins required.

Question 3

A large e-commerce platform is experiencing performance issues due to an increasing volume of user transactions. The database team decides to implement sharding to improve scalability and performance. They plan to shard the user data based on geographical regions. If the total user base is 1,000,000 and they decide to create 10 shards, how many users should ideally be allocated to each shard to maintain an even distribution? Additionally, if one shard experiences a sudden spike in traffic, what would be the best approach to handle this situation without affecting the overall performance of the database?

Accepted Answer

Each shard should ideally handle 100,000 users, and the best approach is to implement dynamic sharding to redistribute users based on real-time traffic patterns.

Question 4

A company is planning to migrate its on-premises Oracle database to Amazon Aurora using the AWS Schema Conversion Tool (SCT). The database contains multiple schemas, each with various tables, stored procedures, and triggers. During the conversion process, the team encounters a stored procedure that uses Oracle-specific PL/SQL features not directly supported in Aurora. What is the best approach for the team to handle this situation while ensuring minimal disruption to the application?

Accepted Answer

Rewrite the stored procedure using Aurora-compatible SQL syntax and test it thoroughly before migration.

Question 5

A company is planning to migrate its on-premises relational database to Amazon RDS for MySQL. They have a requirement to maintain high availability and automatic failover. The database will be used for a critical application that requires minimal downtime. Which configuration should the company implement to meet these requirements while ensuring data durability and performance?

Accepted Answer

Multi-AZ deployment with read replicas

Question 6

A retail company is designing a new application to manage its product inventory. The application needs to store various attributes of products, such as name, price, category, and specifications. The company is considering using a key-value store versus a document database for this purpose. Given the requirements, which data model would be more suitable for handling complex product specifications that may vary significantly between different products, and why?

Accepted Answer

Document database

Question 7

A financial services company is looking to integrate data from multiple sources, including a relational database, a NoSQL database, and a streaming data platform. They want to ensure that the data is harmonized and available for real-time analytics. Which data integration technique would be most effective in this scenario to achieve low-latency data processing while maintaining data consistency across these diverse sources?

Accepted Answer

Change Data Capture (CDC)

Question 8

In a cloud-based database environment, a company is considering implementing a machine learning model to optimize its data retrieval processes. The model will analyze historical query patterns to predict future queries and pre-fetch relevant data. If the model achieves a 30% reduction in average query response time, and the current average response time is 200 milliseconds, what will be the new average response time after implementing the model? Additionally, if the company processes 1,000 queries per minute, how much time will be saved in total per hour due to this optimization?

Accepted Answer

140 milliseconds; 36,000 seconds saved per hour

Question 9

A company is designing a new database to manage its customer orders and inventory. They want to ensure that the database adheres to normalization principles to minimize redundancy and improve data integrity. The database will include tables for Customers, Orders, Products, and OrderDetails. If the company decides to implement third normal form (3NF), which of the following design choices would best support this goal while ensuring efficient data retrieval and maintaining relationships between the tables?

Accepted Answer

Each table should have a primary key, and all non-key attributes must depend only on the primary key, with no transitive dependencies present.

Question 10

A financial institution is implementing a new database system that will store sensitive customer information, including personal identification numbers (PINs) and credit card details. The institution is considering two approaches for securing this data: encrypting the data at rest using AES-256 encryption and encrypting data in transit using TLS 1.2. Which combination of encryption strategies provides the most comprehensive security for the data, considering both storage and transmission?

Accepted Answer

Encrypting data at rest with AES-256 and encrypting data in transit with TLS 1.2

Question 11

A retail company is implementing a new inventory management system that utilizes a key-value store to manage product data. Each product is represented by a unique key, and the associated value contains various attributes such as price, quantity, and description. The company needs to ensure that the system can efficiently handle a high volume of read and write operations, especially during peak shopping seasons. Given this scenario, which of the following strategies would best optimize the performance of the key-value store while maintaining data consistency?

Accepted Answer

Implementing a caching layer to store frequently accessed data in memory, reducing the number of direct database queries.

Question 12

In a scenario where a company is migrating its existing relational database to MongoDB, they need to ensure that their application can handle the differences in data modeling and querying capabilities. The application currently uses SQL for data manipulation and retrieval. Which of the following strategies would best facilitate a smooth transition to MongoDB while maintaining compatibility with the existing application logic?

Accepted Answer

Implement a data access layer that abstracts the database interactions, allowing the application to use a unified API for both SQL and MongoDB queries.

Question 13

A company is experiencing performance issues with its relational database due to an increase in user traffic. The database currently holds 10 million records, and the average query time has increased to 2 seconds. To improve performance, the company is considering implementing sharding. If they decide to shard the database into 5 equal parts, what would be the expected average query time per shard, assuming that the query time is directly proportional to the number of records in each shard?

Accepted Answer

0.4 seconds

Question 14

A company is planning to migrate its existing MySQL database to Amazon Aurora Serverless to handle variable workloads. They expect their database usage to fluctuate significantly, with peak usage reaching 200 connections and a minimum of 20 connections during off-peak hours. The company wants to ensure that they only pay for the resources they use while maintaining performance. Given this scenario, which of the following statements best describes how Amazon Aurora Serverless manages capacity and scaling in response to these workload changes?

Accepted Answer

Amazon Aurora Serverless automatically adjusts the database's capacity based on the current workload, scaling up or down in increments of 0.5 Aurora Capacity Units (ACUs) to accommodate the number of active connections and queries without manual intervention.

Question 15

A database administrator is tasked with optimizing a complex SQL query that retrieves sales data from a large e-commerce database. The query currently performs a full table scan on the `orders` table, which contains millions of records. The administrator considers adding an index on the `order_date` column to improve performance. However, the `orders` table is frequently updated, and the administrator is concerned about the potential impact on write performance. What is the most effective approach to balance read and write performance while optimizing the query?

Accepted Answer

Create a composite index on both `order_date` and `customer_id` to enhance query performance without significantly impacting write operations.

Question 16

A financial services company is migrating its customer transaction database to Amazon Aurora to improve performance and scalability. They need to ensure that their database is optimized for read-heavy workloads while maintaining high availability. Which best practice should they implement to achieve this goal?

Accepted Answer

Use read replicas to offload read traffic from the primary instance.

Question 17

A company is planning to migrate its on-premises relational database to AWS. They are considering using Amazon RDS for PostgreSQL due to its managed service capabilities. The database currently handles an average of 500 transactions per second (TPS) and has a peak load of 1500 TPS during business hours. The company wants to ensure that the new setup can handle the peak load with a buffer for future growth. They are evaluating the use of read replicas to improve read performance and scalability. If they decide to implement one read replica, what would be the expected maximum read throughput they could achieve, assuming the primary instance can handle the peak load effectively and that the read replica can handle the same load as the primary instance?

Accepted Answer

3000 TPS

Question 18

A company is experiencing rapid growth and anticipates a significant increase in user traffic to its online platform. The current database architecture is a single-instance relational database that struggles to handle the load during peak times. To address scalability, the company is considering moving to a distributed database system. Which of the following strategies would best enhance the scalability of their database while ensuring data consistency and availability?

Accepted Answer

Implementing a sharding strategy to distribute data across multiple database instances while using a consensus algorithm for maintaining consistency.

Question 19

A financial services company is evaluating different Database Management Systems (DBMS) to handle its transaction processing needs. The company requires a system that can efficiently manage large volumes of transactions while ensuring data integrity and consistency. They are considering both relational and non-relational databases. Which of the following characteristics is most critical for the DBMS to support high transaction throughput while maintaining ACID properties?

Accepted Answer

Support for multi-version concurrency control (MVCC)

Question 20

A database administrator is tasked with optimizing a complex SQL query that retrieves sales data from multiple tables, including `orders`, `customers`, and `products`. The current query uses multiple nested subqueries and joins, resulting in slow performance. The administrator considers several optimization techniques. Which of the following techniques would most effectively improve the performance of this query while maintaining the integrity of the data retrieval?

Accepted Answer

Refactoring the query to use Common Table Expressions (CTEs) instead of nested subqueries

Question 21

A financial services company operates a critical application that processes transactions in real-time. To ensure high availability and disaster recovery, the company has implemented a multi-region architecture using AWS services. During a recent audit, it was discovered that the application experiences a Recovery Time Objective (RTO) of 4 hours and a Recovery Point Objective (RPO) of 30 minutes. If a disaster occurs in the primary region, what is the maximum acceptable data loss in terms of transactions, assuming the application processes an average of 1,200 transactions per minute?

Accepted Answer

600 transactions

Question 22

A company is experiencing intermittent performance issues with its Amazon RDS instance, which is running a PostgreSQL database. The database is configured with a provisioned IOPS storage type, and the team has set up CloudWatch alarms to monitor key metrics. During peak usage hours, the team notices that the CPU utilization is consistently above 80%, and the read/write latency is increasing. What steps should the team take to diagnose and resolve the performance issues effectively?

Accepted Answer

Analyze the CloudWatch metrics for CPU utilization and IOPS, and consider scaling the instance type or increasing the provisioned IOPS.

Question 23

In a multi-region database deployment on AWS, a company has implemented a failover mechanism to ensure high availability. During a simulated failover test, the primary database instance in Region A becomes unavailable. The failover process is designed to promote the read replica in Region B to become the new primary database. If the read replica has a replication lag of 5 seconds at the time of failover, and the application is configured to tolerate a maximum downtime of 10 seconds, what is the maximum amount of data that could potentially be lost during this failover process, assuming the application processes 100 transactions per second?

Accepted Answer

500 transactions

Question 24

A company is evaluating its database architecture for a new application that is expected to experience variable workloads, with peak usage during specific hours of the day. The application will require a database that can automatically scale to handle sudden spikes in traffic without manual intervention. Given these requirements, which database option would best suit the company\'s needs while minimizing costs during off-peak hours?

Accepted Answer

Amazon Aurora Serverless

Question 25

A database administrator is analyzing the execution plan of a complex SQL query that joins multiple tables and includes several filtering conditions. The execution plan indicates that a nested loop join is being used, and the estimated cost of the operation is significantly higher than expected. The administrator notices that one of the tables involved in the join has a large number of rows, and the filtering condition on this table is not selective. What could be the most effective approach to optimize the query execution plan in this scenario?

Accepted Answer

Rewrite the query to use a hash join instead of a nested loop join, especially if the filtering condition can be applied earlier in the query execution.

Question 26

A retail company is analyzing its sales data to improve inventory management and customer satisfaction. They have a data warehouse that aggregates data from various sources, including point-of-sale systems, online sales, and customer feedback. The company wants to implement a star schema for their data warehouse design. Which of the following best describes the advantages of using a star schema in this context?

Accepted Answer

It simplifies complex queries and enhances query performance by reducing the number of joins needed between tables.

Question 27

In the context of AWS compliance programs, a financial services company is preparing for an audit to ensure adherence to the Payment Card Industry Data Security Standard (PCI DSS). The company has implemented various security measures, including encryption, access controls, and regular vulnerability assessments. However, they are unsure about the specific requirements for maintaining compliance with PCI DSS while utilizing AWS services. Which of the following statements best describes the shared responsibility model in relation to PCI DSS compliance on AWS?

Accepted Answer

AWS is responsible for the security of the cloud infrastructure, while the customer is responsible for securing their applications and data, including compliance with PCI DSS requirements.

Question 28

A company is planning to migrate its on-premises relational database to AWS. They have a large volume of data that requires high availability and scalability. The database must support complex queries and transactions while ensuring minimal downtime during the migration process. Which AWS database service would best meet these requirements while also providing the ability to scale read and write operations seamlessly?

Accepted Answer

Amazon Aurora

Question 29

A financial services company is looking to implement a machine learning model to predict customer churn based on various features such as transaction history, customer demographics, and service usage patterns. They have a dataset containing 10,000 records, with 70% of the data allocated for training and 30% for testing. The company decides to use a logistic regression model for this binary classification problem. After training the model, they achieve an accuracy of 85% on the test set. However, they notice that the model\'s precision is significantly lower than its recall. What could be the most effective approach to improve the model\'s performance in terms of precision without sacrificing recall?

Accepted Answer

Implementing a threshold adjustment to increase the classification threshold for positive predictions

Question 30

A financial services company is planning to implement a data lake using Amazon S3 to store various types of data, including structured, semi-structured, and unstructured data. They want to ensure that their data lake is optimized for analytics and machine learning workloads. Given their requirements, which of the following strategies should they prioritize to maximize performance and cost-effectiveness in their data lake architecture?

Accepted Answer

Utilize S3 Intelligent-Tiering to automatically move data between access tiers based on changing access patterns.

Amazon DBS-C01 AWS Certified Database – Specialty (DBS-C01) Free Practice Test — 30 Questions

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