Amazon Web Services Updated SAA-C03 Exam Questions and Answers by alaia

 Security groups are virtual firewalls that protect AWS instances and can be applied to EC2, ELB and RDS1. Security groups have rules for inbound and outbound traffic and are stateful, meaning that responses to allowed inbound traffic are allowed to flow out of the instance2. Network ACLs are different from security groups in several ways. They cover entire subnets, not individual instances, and are stateless, meaning that they require rules for both inbound and outbound traffic2. Network ACLs also support deny rules, while security groups only support allow rules2.

To meet the requirements of the scenario, the solutions architect should create two security groups: one for the DB instance and one for the web servers in the public subnet. The security group for the DB instance should allow traffic from the public subnet CIDR block on port 3306, which is the default port for MySQL3. This way, only the web servers in the public subnet can access the DB instance on that port. The security group for the web servers should allow traffic from 0 0 0 O’O on port 443, which is the default port forHTTPS4. This way, the web servers can accept secure connections from the internet on that port.

https://docs.aws.amazon.com/sns/latest/dg/sns-server-side-encryption.htmlhttps://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-server-side-encryption.html

This option is the most efficient because it uses aMulti-AZ deployment for the DB instance, which provides enhanced availability and durability for RDS database instances by automatically replicating the data to a standby instance in a different AvailabilityZone1. It also provides a recovery point objective (RPO) of less than 1 second for all its production databases, as the standby instance is kept in sync with the primary instanceusing synchronous physical replication2. This solution meets the requirement of requiring a RPO of less than 1 second for all its production databases. Option B is less efficientbecause it uses auto scaling for the DB instance in one Availability Zone, which is a way to automatically adjust the compute capacity of your DB instance based on load or a schedule3. However, this does not provide a RPO of lessthan 1 second for all its production databases, as it does not replicate the data to another Availability Zone. Option C is less efficient because it uses read replicas in a separate Availability Zone, which are read-only copies of your primary database that can serve read traffic and support scaling. However, this does not provide a RPO of less than 1 second for all its production databases, as read replicas use asynchronous replication and can lag behind the primary database. Option D is less efficient because it uses AWS Database Migration Service (AWS DMS) change data capture (CDC) tasks, which are tasks that capture changes made to source data and apply them to target data. However, this does not provide a RPO of less than 1 second for all its production databases, as AWS DMS uses asynchronous replication and can lag behind the source database.

https://docs.aws.amazon.com/autoscaling/application/userguide/what-is-application-auto-scaling.html