Amazon Web Services Updated CLF-C02 Exam Questions and Answers by jorge

S3 Versioning is a feature that allows you to keep multiple versions of an object in the same bucket. You can use S3 Versioning to protect your data from accidental deletion or overwriting by enabling it on a bucket or a specific object. S3 Versioning also allows you to restore previous versions of an object if needed. S3 Lifecycle rules are used to automate the transition of objects between storage classes or to expire objects after a certain period of time. S3 bucket policies are used to control access to the objects in a bucket. S3 server-side encryption is used to encrypt the data at rest in S3. References: S3 Versioning, S3 Lifecycle rules, S3 bucket policies, S3 server-side encryption

 These are two scenarios that represent the concept of elasticity on AWS. Elasticity means the ability to adjust the resources and capacity of the system in response to changes in demand or environment. Scaling the number of Amazon EC2 instances based on traffic means using services such as AWS Auto Scaling or Elastic Load Balancing to add or remove instances as the traffic increases or decreases. Resizing Amazon RDS instances as business needs change means using the Amazon RDS console or API to modify the instance type, storage type, or storage size of the database as the workload grows or shrinks. You can learn more about the concept of elasticity on AWS from [this webpage] or [this digital course].

"The Reliability pillar encompasses the ability of a workload to perform its intended function correctly and consistently when it’s expected to. This includes the ability to operate and test the workload through its total lifecycle. " https://docs.aws.amazon.com/wellarchitected/latest/framework/reliability.html

A network ACL (NACL) is an optional layer of security for your VPC that acts as a firewall for controlling traffic in and out of one or more subnets. You can create a network ACL and associate it with a subnet to apply rules that allow or deny traffic to or from the subnet. Network ACLs are stateless, meaning that they evaluate the source and destination IP addresses for both inbound and outbound traffic. You can also use network ACLs to block IP address ranges that are known to be malicious12.

The other options are not AWS services or tools that can be used to set up a firewall to control traffic going into and coming out of an Amazon VPC subnet. Security groups are another layer of security for your VPC that act as a firewall for your EC2 instances. Security groups are stateful, meaning that they automatically allow return traffic for allowed inbound traffic. Security groups can only filter traffic based on protocols, ports, and source or destination IP addresses, not on IP ranges3. AWS WAF is a web application firewall that helps protect your web applications from common web exploits. AWS WAF can filter web requests based on rules that you define, such as IP addresses, HTTP headers, HTTP body, or URI strings. AWS WAF does not apply to non-web traffic or to traffic within a VPC4. AWS Firewall Manager is a service that helps you centrally configure and manage firewall rules across your accounts and resources in AWS Organizations. You can use Firewall Manager to apply AWS WAF rules, AWS Network Firewall policies, and Amazon VPC security groups across your AWS accounts. AWS Firewall Manager does not provide a firewall service itself, but rather helps you manage other firewall services