An Availability Zone in a Region has exhausted its IP address allocation and currently uses 10.10.1.0/24. The VPC CIDR is 10.10.0.0/16 and there is available space such that 10.10.1.0/22 would fit within the VPC. Network configurations are managed via CloudFormation. What change will add additional IP addresses to the existing VPC with the least operational overhead?

The correct solution is to add a new AWS::EC2::Subnet resource. You cannot directly modify the CIDR block of an existing subnet (10.10.1.0/24) to a larger block (10.10.1.0/22) without recreating the subnet, which would cause downtime for resources within it. Adding a new subnet (10.10.2.0/24) within the same Availability Zone provides additional IP addresses from the available VPC CIDR space (10.10.0.0/16) with the least operational overhead, as existing resources remain unaffected. Updating the VPC's CIDR block to 10.10.1.0/22 is incorrect because the VPC already has a 10.10.0.0/16 CIDR, and you cannot change the primary CIDR block of an existing VPC. Duplicating the stack is unnecessary and complex.