Selected SAA-C03 AWS Certified Associate Questions Answers

The company wants to reduce the compute costs and maintain service latency for its Lambda functions that process a constantly increasing number of messages in a message queue. The Lambda functions use CPU intensive code to process the messages. To meet these requirements, a solutions architect should recommend the following solution:

Configure provisioned concurrency for the Lambda functions. Provisioned concurrency is the number of pre-initialized execution environments that are allocated to the Lambda functions. These execution environments are prepared to respond immediately to incoming function requests, reducing the cold start latency. Configuring provisioned concurrency also helps to avoid throttling errors due to reaching the concurrency limit of the Lambda service.

Increase the memory according to AWS Compute Optimizer recommendations. AWS Compute Optimizer is a service that provides recommendations for optimal AWS resource configurations based on your utilization data. By increasing the memory allocated to the Lambda functions, you can also increase the CPU power and improve the performance of your CPU intensive code. AWS Compute Optimizer can help you find the optimal memory size for your Lambda functions based on your workload characteristics and performance goals.

This solution will reduce the compute costs by avoiding unnecessary over-provisioning of memory and CPU resources, and maintain service latency by using provisioned concurrency and optimal memory size for the Lambda functions.

References:

Provisioned Concurrency

AWS Compute Optimizer

The most cost-effective DynamoDB table configuration for the web application is to configure DynamoDB in on-demand mode by using the DynamoDB Standard table class. This configuration will allow the company to scale in response to application traffic and pay only for the read and write requests that the application performs on the table.

On-demand mode is a flexible billing option that can handle thousands of requests per second without capacity planning. On-demand mode automatically adjusts the table’s capacity based on the incoming traffic, and charges only for the read and write requests that are actually performed. On-demand mode is suitable for applications with unpredictable or variable workloads, or applications that prefer the ease of paying for only what they use1.

The DynamoDB Standard table class is the default and recommended table class for most workloads. The DynamoDB Standard table class offers lower throughput costs than the DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA) table class, and is more cost-effective for tables where throughput is the dominant cost. The DynamoDB Standard table class also offers the same performance, durability, and availability as the DynamoDB Standard-IA table class2.

The other options are not correct because they are either not cost-effective or not suitable for the use case. Configuring DynamoDB with provisioned read and write by using the DynamoDB Standard table class, and setting DynamoDB auto scaling to a maximum defined capacity is not correct because this configuration requires manual estimation and management of the table’s capacity, which adds complexity and cost to the solution. Provisioned mode is a billing option that requires users to specify the amount of read and write capacity units for their tables, and charges for the reserved capacity regardless of usage. Provisioned mode is suitable for applications with predictable or stable workloads, or applications that require finer-grained control over their capacity settings1. Configuring DynamoDB with provisioned read and write by using the DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA) table class, and setting DynamoDB auto scaling to a maximum defined capacity is not correct because this configuration is not cost-effective for tables with moderate to high throughput. The DynamoDB Standard-IA table class offers lower storage costs than the DynamoDB Standard table class, but higher throughput costs. The DynamoDB Standard-IA table class is optimized for tables where storage is the dominant cost, such as tables that store infrequently accessed data2. Configuring DynamoDB in on-demand mode by using the DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA) table class is not correct because this configuration is not cost-effective for tables with moderate to high throughput. As mentioned above, the DynamoDB Standard-IA table class has higher throughput costs than the DynamoDB Standard table class, which can offset the savings from lower storage costs.

References:

Table classes - Amazon DynamoDB

Read/write capacity mode - Amazon DynamoDB

The most suitable solution for the company’s requirements is to enable Default Host Configuration Management in Systems Manager to manage the EC2 instances. This solution will allow the company to patch the EC2 instances without disrupting the running applications and without manually creating or modifying IAM roles or users.

Default Host Configuration Management is a feature of AWS Systems Manager that enables Systems Manager to manage EC2 instances automatically as managed instances. A managed instance is an EC2 instance that is configured for use with Systems Manager. The benefits of managing instances with Systems Manager include the following:

Connect to EC2 instances securely using Session Manager.

Perform automated patch scans using Patch Manager.

View detailed information about instances using Systems Manager Inventory.

Track and manage instances using Fleet Manager.

Keep SSM Agent up to date automatically.

Default Host Configuration Management makes it possible to manage EC2 instances without having to manually create an IAM instance profile. Instead, Default Host Configuration Management creates and applies a default IAM role to ensure that Systems Manager has permissions to manage all instances in the Region and account where it is activated. If the permissions provided are not sufficient for the use case, the default IAM role can be modified or replaced with a custom role1.

The other options are not correct because they either have more operational overhead or do not meet the requirements. Creating a new IAM role, attaching the AmazonSSMManagedInstanceCore policy to the new IAM role, and attaching the new IAM role and the existing IAM role to the EC2 instances is not correct because this solution requires manual creation and management of IAM roles, which adds complexity and cost to the solution. The AmazonSSMManagedInstanceCore policy is a managed policy that grants permissions for Systems Manager core functionality2. Creating an IAM user, attaching the AmazonSSMManagedInstanceCore policy to the IAM user, and configuring Systems Manager to use the IAM user to manage the EC2 instances is not correct because this solution requires manual creation and management of IAM users, which adds complexity and cost to the solution. An IAM user is an identity within an AWS account that has specific permissions for a single person or application3. Removing the existing policies from the existing IAM role and adding the AmazonSSMManagedInstanceCore policy to the existing IAM role is not correct because this solution may disrupt the running applications that rely on the existing policies for accessing RDS databases. An IAM role is an identity within an AWS account that has specific permissions for a service or entity4.

References:

AWS managed policy: AmazonSSMManagedInstanceCore

IAM users

IAM roles

Default Host Management Configuration - AWS Systems Manager

This solution meets the requirements most securely because it uses IAM roles and the STS AssumeRole API operation to authenticate and authorize the inventory application to access the DynamoDB tables in different accounts. IAM roles are more secure than IAM users or certificates because they do not require long-term credentials or passwords. Instead, IAM roles provide temporary security credentials that are automatically rotated and can be configured with a limited duration. The STS AssumeRole API operation enables you to request temporary credentials for a role that you are allowed to assume. By using this operation, you can delegate access to resources that are in different AWS accounts that you own or that are owned by third parties. The trust policy of the role defines which entities can assume the role, and the permissions policy of the role defines which actions can be performed on the resources. By using this solution, you can avoid hard-coding credentials or certificates in the inventory application, and you can also avoid storing them in Secrets Manager or ACM. You can also leverage the built-in security features of IAM and STS, such as MFA, access logging, and policy conditions.

References:

IAM Roles

STS AssumeRole

Tutorial: Delegate Access Across AWS Accounts Using IAM Roles