AWS Certified SysOps Administrator - Associate

To make an application highly available, it's essential to distribute the resources across multiple Availability Zones within the same AWS Region. This ensures that the application can continue to operate even if one Availability Zone experiences an outage. Updating the Auto Scaling group to launch new instances in a second Availability Zone in the same AWS Region achieves this goal by providing redundancy and failover capability, thus maintaining high availability. Adjusting the number of instances, as stated in options A and B, only addresses capacity and does not provide the required high availability. Option D is incorrect because Auto Scaling groups are designed to operate within a single AWS Region, and using an Availability Zone in another AWS Region would not be feasible for this purpose.

The most operationally efficient solution for improving performance during predictable peak times is to configure a scheduled scaling action with a recurrence option to change the desired capacity before and after peak times. This allows the system to automatically adjust the number of instances at specific times, ensuring adequate resources are available during peak usage without manual intervention. Scheduled scaling is ideal for scenarios with known patterns of demand.

To resolve the issue of mobile users being served the desktop version of the website, the correct action is to configure the CloudFront distribution behavior to forward the User-Agent header. The User-Agent header contains information about the client's device and browser. By forwarding this header, CloudFront can help the origin (the Application Load Balancer) to distinguish between requests from mobile and desktop users, allowing the application to serve the appropriate version of the website based on the user's device type. This approach ensures that users receive the correct content regardless of the device they use to access the website.

To ensure that CloudTrail is re-enabled automatically without writing custom code, create an AWS Config rule that is triggered when there are changes to CloudTrail's configuration. Then apply the AWS-ConfigureCloudTrailLogging automatic remediation action. This configuration will automatically monitor changes to CloudTrail and re-enable it if it gets disabled, aligning with the requirements of the question.

To point a domain's zone apex to an Amazon EC2 instance behind an Application Load Balancer (ALB) using Route 53, you need to use an alias record. The DNS protocol does not allow the creation of a CNAME record at the zone apex. However, an alias record can be used at the zone apex to point to AWS resources such as an ALB. Address records (A or AAAA) would not be appropriate as they translate domain names to specific IP addresses, not to load balancers or other AWS resources.