The wording on this question makes things ambiguous for C. But, remember well-architected so: A: Not ideal as it is suggesting using existing architecture but with autoscaling EC2. Doesn't leave room for improvement on scaling or reliability on each tier. B: Single RDS, not well-architected D: Again, single RDS E,F are good options and C is only remaining good one.

C-scalable and resilient E-high availability of the application F-Multi-AZ configuration provides high availability

remove singles and remove network ACLs

i would flag this on the test and do it last.

option A cannot be the answer as Security group is at instance level whereas a NACL is at the subnet level. Having said that option C is the right one as the VPC cannot span across the regions and here it is mentioned two AZs for which I am guessing it is a default VPC which is created in each region with a subnet in each AZ.

How can you create a VPC across 2 AZ? i only see EF here.. if they mean 2 separate VPC then that is different but a VPC cannot span two AZ..

I also agree with CEF but chatGPT answer is ACE. A and C is the similar Another Logic F is not True because in the question not mentioned about DB

CEF is best

It's clearly CEF.

B- to control access to database C-scalable and resilient E-high availability of the application

CEF A: application's existing architecture is wrong (single AZ) B: single AZ D: Single AZ

C. This solution follows the recommended architecture pattern of separating the web, application, and database tiers into different subnets. It provides better security, scalability, and fault tolerance. E.By using Elastic Load Balancers (ELBs), you can distribute traffic to multiple instances of the web tier, increasing scalability and availability. Controlling access through security groups allows for fine-grained control and ensures only authorized traffic reaches each layer. F. Deploying an Amazon RDS database in a Multi-AZ configuration provides high availability and automatic failover. Placing the database in private subnets enhances security. Allowing database access only from the application tier security groups limits exposure and follows the principle of least privilege.

Only this valid for best practices and well architected