ANS-C01 Exam Dumps : Amazon AWS Certified Advanced Networking - Specialty

To resolve the issue of intermittent connections for traffic that crosses Availability Zones after configuring routing for traffic inspection between VPCs using a transit gateway and EC2 instances with IDS services in a shared services VPC, a network engineer should modify the transit gateway VPC attachment on the shared services VPC by enabling appliance mode support (Option B). This will ensure that traffic is routed to the same EC2 instance for stateful inspection and prevent intermittent connections.

The most operationally efficient way to restrict inbound traffic to the ALB to come from CloudFront is to use the AWS managed prefix list for CloudFront. A prefix list is a collection of CIDR blocks that can be used to configure security groups and network ACLs. AWS provides a managed prefix list for CloudFront that is automatically updated when CloudFront IP ranges change. By adding an inbound rule to the ALB’s security group to allow the AWS managed prefix list for CloudFront, the network engineer can ensure that only CloudFront can access the ALB at the network layer. This solution does not require any additional configuration or maintenance. Option B is less efficient because network ACLs are stateless and require rules for both inbound and outbound traffic. Option C is not a network layer solution, but an application layer solution that requires the ALB to inspect the HTTP headers and reject requests that do not have the custom header. Option D is also not a network layer solution, but a web layer solution that requires AWS WAF to filter the traffic based on the CloudFront IP set. This solution also requires an AWS Lambda function to update the CloudFront IP set, which adds complexity and cost