Pass CLF-C02 Exam Guide

 AWS Config is a service that enables users to assess, audit, and evaluate the configurations of AWS resources. It continuously monitors and records the configuration changes of the resources and evaluates them against desired configurations and best practices. It also provides a detailed view of the resource configuration history and relationships, as well as compliance reports and notifications. AWS Config can help users maintain consistent and secure configurations, troubleshoot issues, and simplify compliance auditing. AWS Config OverviewAWS Certified Cloud Practitioner - aws.amazon.com

The correct answer is B because Amazon ElastiCache is a service that provides in-memory data storage. Amazon ElastiCache is a fully managed, scalable, and high-performance service that supports two popular open-source in-memory engines: Redis and Memcached. Amazon ElastiCache allows users to store and retrieve data from fast, low-latency, and high-throughput in-memory systems. Users can use Amazon ElastiCache to improve the performance of their applications by caching frequently accessed data, reducing database load, and enabling real-time data processing. The other options are incorrect because they are not services that provide in-memory data storage. Amazon DynamoDB is a service that provides key-value and document data storage. Amazon RDS is a service that provides relational data storage. Amazon Timestream is a service that provides time series data storage. Reference: Amazon ElastiCache FAQs

 Security groups are the service or feature that meets the requirement of establishing a security layer in a VPC that will act as a firewall to control subnet traffic. Security groups are stateful firewalls that control the inbound and outbound traffic at the instance level. You can assign one or more security groups to each instance in a VPC, and specify the rules that allow or deny traffic based on the protocol, port, and source or destination. Security groups are associated with network interfaces, and therefore apply to all the instances in the subnets that use those network interfaces. Routing tables are used to direct traffic between subnets and gateways, not to filter traffic. Network ACLs are stateless firewalls that control the inbound and outbound traffic at the subnet level, but they are less granular and more cumbersome to manage than security groups. Amazon GuardDuty is a threat detection service that monitors your AWS account and workloads for malicious or unauthorized activity, not a firewall service.

 AWS Lambda is a compute service that lets you run code without provisioning or managing servers. AWS Lambda executes your code only when needed and scales automatically, from a few requests per day to thousands per second. You pay only for the compute time you consume - there is no charge when your code is not running. With AWS Lambda, you can run code for virtually any type of application or backend service - all with zero administration. AWS Lambda runs your code on a high-availability compute infrastructure and performs all of the administration of the compute resources, including server and operating system maintenance, capacity provisioning and automatic scaling, code monitoring and logging