- (Topic 3)
A company has launched an Amazon RDS for MySQL D6 instance Most of the connections to the database come from serverless applications. Application traffic to the database changes significantly at random intervals At limes of high demand, users report that their applications experience database connection rejection errors.
Which solution will resolve this issue with the LEAST operational overhead?

1. A. Create a proxy in RDS Proxy Configure the users' applications to use the DB instance through RDS Proxy
2. B. Deploy Amazon ElastCache for Memcached between the users' application and the DB instance
3. C. Migrate the DB instance to a different instance class that has higher I/O capacit
4. D. Configure the users' applications to use the new DB instance.
5. E. Configure Multi-AZ for the DB instance Configure the users' application to switch between the DB instances.

Correct Answer: A
Many applications, including those built on modern serverless architectures, can have a large number of open connections to the database server and may open and close database connections at a high rate, exhausting database memory and compute resources. Amazon RDS Proxy allows applications to pool and share connections established with the database, improving database efficiency and application scalability. (https://aws.amazon.com/pt/rds/proxy/)

- (Topic 4)
A company wants to experiment with individual AWS accounts for its engineer team. The company wants to be notified as soon as the Amazon EC2 instance usage for a given month exceeds a specific threshold for each account.
What should a solutions architect do to meet this requirement MOST cost-effectively?

1. A. Use Cost Explorer to create a daily report of costs by servic
2. B. Filter the report by EC2instance
3. C. Configure Cost Explorer to send an Amazon Simple Email Service (Amazon SES) notification when a threshold is exceeded.
4. D. Use Cost Explorer to create a monthly report of costs by servic
5. E. Filter the report by EC2 instance
6. F. Configure Cost Explorer to send an Amazon Simple Email Service (Amazon SES) notification when a threshold is exceeded.
7. G. Use AWS Budgets to create a cost budget for each accoun
8. H. Set the period to monthl
9. I. Set the scope to EC2 instance
10. J. Set an alert threshold for the budge
11. K. Configure an Amazon Simple Notification Service (Amazon SNS) topic to receive a notification when a threshold is exceeded.
12. L. Use AWS Cost and Usage Reports to create a report with hourly granularit
13. M. Integrate the report data with Amazon Athen
14. N. Use Amazon EventBridge to schedule an Athena quer
15. O. Configure an Amazon Simple Notification Service (Amazon SNS) topic to receive a notification when a threshold is exceeded.

Correct Answer: C
AWS Budgets allows you to create budgets for your AWS accounts and set alerts when usage exceeds a certain threshold. By creating a budget for each account, specifying the period as monthly and the scope as EC2 instances, you can effectively track the EC2 usage for each account and be notified when a threshold is exceeded. This solution is the most cost-effective option as it does not require additional resources such as Amazon Athena or Amazon EventBridge.

- (Topic 3)
A company collects data from a large number of participants who use wearabledevices.The company stores the data in an Amazon DynamoDB table and uses applications to analyze the data. The data workload is constant and predictable. The company wants to stay at or below its forecasted budget for DynamoDB.
Whihc solution will meet these requirements MOST cost-effectively?

1. A. Use provisioned mode and DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA). Reserve capacity for the forecasted workload.
2. B. Use provisioned mode Specify the read capacity units (RCUs) and write capacity units (WCUs).
3. C. Use on-demand mod
4. D. Set the read capacity unite (RCUs) and write capacity units (WCUs) high enough to accommodate changes in the workload.
5. E. Use on-demand mod
6. F. Specify the read capacity units (RCUs) and write capacity units (WCUs) with reserved capacity.

Correct Answer: B
This option is the most efficient because it uses provisioned mode, which is a read/write capacity mode for processing reads and writes on your tables that lets you specify how much read and write throughput you expect your application to perform1. It also specifies the read capacity units (RCUs) and write capacity units (WCUs), which are the amount of data your application needs to read or write per second. It also meets the requirement of staying at or below its forecasted budget for DynamoDB, as provisioned mode has lower costs than on-demand mode for predictable workloads. This solution meets the requirement of collecting data from a large number of participants who use wearable devices with a constant and predictable data workload. Option A is less efficient because it uses provisioned mode and DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA), which is a storage class for infrequently accessed items that require milliseconds latency2. However, this does not meet the requirement of collecting data from a large number of participants who use wearable devices with a constant and predictable data workload, as DynamoDB Standard-IA is more suitable for items that are accessed less frequently than once every 30 days. Option C is less efficient because it uses on- demand mode, which is a read/write capacity mode that lets you pay only for what you use by automatically adjusting your table’s capacity in response to changing demand3. However, this does not meet the requirement of staying at or below its forecasted budget
for DynamoDB, as on-demand mode has higher costs than provisioned mode for predictable workloads. Option D is less efficient because it uses on-demand mode and specifies the RCUs and WCUs with reserved capacity, which is a way to reserve read and write capacity for your tables in exchange for discounted hourly rates. However, this does not meet the requirement of staying at or below its forecasted budget for DynamoDB, as on-demand mode has higher costs than provisioned mode for predictable workloads. Also, specifying RCUs and WCUs with reserved capacity is not possible with on-demand mode, as it only applies to provisioned mode.

- (Topic 4)
A company hosts a database that runs on an Amazon RDS instance that is deployed to multiple Availability Zones. The company periodically runs a script against the database to report new entries that are added to the database. The script that runs against the database negatively affects the performance of a critical application. The company needs to improve application performance with minimal costs.
Which solution will meet these requirements with the LEAST operational overhead?

1. A. Add functionality to the script to identify the instance that has the fewest active connection
2. B. Configure the script to read from that instance to report the total new entries.
3. C. Create a read replica of the databas
4. D. Configure the script to query only the read replica to report the total new entries.
5. E. Instruct the development team to manually export the new entries for the day in the database at the end of each day.
6. F. Use Amazon ElastiCache to cache the common queries that the script runs against the database.

Correct Answer: B
A read replica is a copy of the primary database that supports read-only queries. By creating a read replica, you can offload the read workload from the primary database and improve its performance. The script can query the read replica without affecting the critical application that uses the primary database. This solution also has the least operational overhead, as you do not need to modify the script, export the data manually, or manage a cache cluster. References:
✑ Working with PostgreSQL, MySQL, and MariaDB Read Replicas
✑ Amazon RDS Performance Insights

- (Topic 2)
A company runs a stateless web application in production on a group of Amazon EC2 On- Demand Instances behind an Application Load Balancer. The application experiences heavy usage during an 8-hour period each business day. Application usage is moderate and steady overnight Application usage is low during weekends.
The company wants to minimize its EC2 costs without affecting the availability of the application.
Which solution will meet these requirements?

1. A. Use Spot Instances for the entire workload.
2. B. Use Reserved instances for the baseline level of usage Use Spot Instances for any additional capacity that the application needs.
3. C. Use On-Demand Instances for the baseline level of usag
4. D. Use Spot Instances for any additional capacity that the application needs
5. E. Use Dedicated Instances for the baseline level of usag
6. F. Use On-Demand Instances for any additional capacity that the application needs

Correct Answer: B
Reserved is cheaper than on demand the company has. And it's meet the availabilty (HA) requirement as to spot instance that can be disrupted at any time. PRICING BELOW. On- Demand: 0% There’s no commitment from you. You pay the most with this option. Reserved : 40%-60%1-year or 3-year commitment from you. You save money from that commitment. Spot 50%-90% Ridiculously inexpensive because there’s no commitment from the AWS side.