Explanation: VPC Flow Logs is the AWS service or feature that is used to troubleshoot network connectivity issues between Amazon EC2 instances. VPC Flow Logs is a feature that enables users to capture information about the IP traffic going to and from network interfaces in their VPC. VPC Flow Logs can help users monitor and diagnose networkrelated issues, such as traffic not reaching an instance, or an instance not responding to requests. VPC Flow Logs can be published to Amazon CloudWatch Logs, Amazon S3, or Amazon Kinesis Data Firehose for analysis and storage.

Explanation: The correct answer is C because Amazon Cognito provides identity federation and user authentication for web and mobile applications. Amazon Cognito allows users to sign in with their social media, email, or online shopping accounts. The other options are incorrect because they do not provide identity federation or user authentication. AWS IAM Identity Center (AWS Single Sign-On) is a service that enables users to access multiple AWS accounts and applications with a single sign-on experience. AWS Config is a service that enables users to assess, audit, and evaluate the configurations of their AWS resources. AWS Identity and Access Management (IAM) is a service that enables users to manage access to AWS resources using users, groups, roles, and policies.

Explanation: The correct answer is B because AWS CloudTrail is an AWS service that a cloud engineer can use to view API calls to AWS services. AWS CloudTrail is a service that enables customers to track user activity and API usage across their AWS account. AWS CloudTrail records the details of every API call made to AWS services, such as the identity of the caller, the time of the call, the source IP address of the caller, the parameters and responses of the call, and more. Customers can use AWS CloudTrail to audit, monitor, and troubleshoot their AWS resources and actions. The other options are incorrect because they are not AWS services that a cloud engineer can use to view API calls to AWS services. Amazon CloudWatch is an AWS service that enables customers to collect, analyze, and visualize metrics, logs, and events from their AWS resources and applications. AWS Config is an AWS service that enables customers to assess, audit, and evaluate the configurations of their AWS resources. AWS Artifact is an AWS service that provides customers with on-demand access to AWS compliance reports and select online agreements.

Explanation: The ability to deploy to AWS on a global scale is a cloud benefit that AWS offers to its users. AWS has a global infrastructure that consists of AWS Regions, Availability Zones, and edge locations. Users can choose from multiple AWS Regions around the world to deploy their applications and data closer to their end users, while also meeting their compliance and regulatory requirements. Users can also leverage AWS services, such as Amazon CloudFront, Amazon Route 53, and AWS Global Accelerator, to improve the performance and availability of their global applications. AWS also provides tools and guidance to help users optimize their global deployments, such as AWS Well- Architected Framework, AWS CloudFormation, and AWS Migration Hub. AWS Global Infrastructure [AWS Cloud Value Framework] AWS Certified Cloud Practitioner - aws.amazon.com

Explanation: Creating an IAM role with the required permissions and attaching the role to the EC2 instance is the most operationally efficient solution to delegate permissions. An IAM role is an entity that defines a set of permissions for making AWS service requests. An IAM role can be assumed by an EC2 instance to access other AWS resources, such as Amazon S3 and Amazon DynamoDB, without having to store any credentials on the instance. This solution is more secure and scalable than using IAM users and their access keys.

Explanation: The correct answers are A and D because network infrastructure and virtualization of infrastructure and physical security of hardware are AWS responsibilities according to the AWS shared responsibility model. The AWS shared responsibility model is a framework that defines the division of responsibilities between AWS and the customer for security and compliance. AWS is responsible for the security of the cloud, which includes the global infrastructure, such as the regions, availability zones, and edge locations; the hardware, software, networking, and facilities that run the AWS services; and the virtualization layer that separates the customer instances and storage. The customer is responsible for the security in the cloud, which includes the customer data, the guest operating systems, the applications, the identity and access management, the firewall configuration, and the encryption. The other options are incorrect because they are not AWS responsibilities according to the AWS shared responsibility model. Security of application data, guest operating systems, and credentials and policies are customer responsibilities according to the AWS shared responsibility model.

Explanation: AWS WAF is the AWS service or feature that offers HTTP attack protection to users running public-facing web applications. AWS WAF is a web application firewall that helps users protect their web applications from common web exploits, such as SQL injection, cross-site scripting, and bot attacks. Users can create custom rules to define the web traffic that they want to allow, block, or count. Users can also use AWS Managed Rules, which are pre-configured rules that are curated and maintained by AWS or AWS Marketplace Sellers. AWS WAF can be integrated with other AWS services, such as Amazon CloudFront, Amazon API Gateway, and Application Load Balancer, to provide comprehensive security for web applications.

Explanation: AWS Config is a service that enables you to assess, audit, and evaluate the configurations of your AWS resources. AWS Config continuously monitors and records your AWS resource configurations and allows you to automate the evaluation of recorded configurations against desired configurations. With AWS Config, you can review changes in configurations and relationships between AWS resources, dive into detailed resource configuration histories, and determine your overall compliance against the configurations specified in your internal guidelines3.

Explanation: AWS Control Tower uses AWS CloudFormation to create resources in your landing zone. AWS CloudFormation is a service that helps you model and set up your AWS resources using templates. AWS Control Tower supports creating AWS::ControlTower::EnabledControl resources in AWS CloudFormation. Therefore, the correct answer is A. You can learn more about AWS Control Tower and AWS CloudFormation.

Explanation: The correct answer is A because an Availability Zone consists of one or more data centers in a single location. An Availability Zone is an isolated location within an AWS Region that has independent power, cooling, and networking. Each Availability Zone has one or more data centers that host the physical servers and storage devices that run the AWS services. The other options are incorrect because they are not accurate descriptions of an Availability Zone. Two or more data centers in multiple locations are not an Availability Zone, but rather multiple Availability Zones within an AWS Region. One or more physical hosts in a single data center are not an Availability Zone, but rather the components of a data center within an Availability Zone. Two or more physical hosts in multiple data centers are not an Availability Zone, but rather the components of multiple data centers within one or more Availability Zones.

Explanation: The correct answer is C because AWS Cloud computing allows customers to trade fixed expenses for variable expenses. This means that customers only pay for the resources they use, and can scale up or down as needed. The other options are incorrect because they are not advantages of AWS Cloud computing. Trade security for elasticity means that customers have to compromise on the protection of their data and applications in order to adjust their capacity quickly. Trade operational excellence for agility means that customers have to sacrifice the quality and reliability of their operations in order to respond to changing needs faster. Trade elasticity for performance means that customers have to limit their ability to scale up or down in order to achieve higher speed and efficiency.

Explanation: Amazon RDS supports six database engines: Amazon Aurora, MySQL, MariaDB, PostgreSQL, Oracle, and SQL Server. Apache Cassandra, MongoDB, and Neo4j are not compatible with Amazon RDS. Therefore, the correct answer is D. You can learn more about Amazon RDS and its supported database engines.