Q32 — AWS SAP-C02 Ch.3

Question 32 of 75 | ← Chapter 3

Q257. A solutions architect has an operational workload deployed on Amazon EC2 instances in an Auto Scaling group. The VPC architecture spans two Availability Zones (AZ) with a subnet in each that the Auto Scaling group is targeting. The VPC is connected to an on-premises environment and connectivity cannot be interrupted. The maximum size of the Auto Scaling group is 20 instances in service. The VPC IPv4 addressing is as follows: VPC CIDR: 10.0.0.0/23 AZ1 subnet CIDR 10.0.0.0/24 AZ2 subnet CIDR: 10.0.1.0/24 Since deployment, a third AZ has become available in the Region. The solutions architect wants to adopt the new AZ without adding additional IPv4 address space and without service downtime. Which solution will meet these requirements?

• A. Update the Auto Scaling group to use the AZ2 subnet only Delete and re-create the AZ1 subnet using half the previous address space. Adjust the Auto Scaling group to also use the new AZ1 subnet. When the instances are healthy, adjust the Auto Scaling group to use the AZ1 subnet only. Remove the current AZ2 subnet. Create a new AZ2 subnet using the second half of the address space from the original AZ1 subnet. Create a new AZ3 subnet using half the original AZ2 subnet address space, then update the Auto Scaling group to target all three new subnets. ✓
• B. Terminate the EC2 instances in the AZ1 subnet. Delete and re-create the AZ1 subnet using half the address space Update the Auto Scaling group to use this new subnet. Repeat this for the second AZ. Define a new subnet in AZ3, then update the Auto Scaling group to target all three new subnets .
• C. Create a new VPC with the same lPv4 address space and define three subnets, with one for each AZ. Update the existing Auto Scaling group to target the new subnets in the new VPC
• D. Update the Auto Scaling group to use the AZ2 subnet only. Update the AZ1 subnet to have half the previous address space. Adjust the Auto Scaling group to also use the AZ1 subnet again. When the instances are healthy, adjust the Auto Scaling group to use the AZ1 subnet only. Update the current AZ2 subnet and assign the second half of the address space from the original AZ1 subnet. Create a new AZ3 subnet using half the original AZ2 subnet address space, then update the Auto Scaling group to target all three new subnets.

Correct Answer: A. Update the Auto Scaling group to use the AZ2 subnet only Delete and re-create the AZ1 subnet using half the previous address space. Adjust the Auto Scaling group to also use the new AZ1 subnet. When the instances are healthy, adjust the Auto Scaling group to use the AZ1 subnet only. Remove the current AZ2 subnet. Create a new AZ2 subnet using the second half of the address space from the original AZ1 subnet. Create a new AZ3 subnet using half the original AZ2 subnet address space, then update the Auto Scaling group to target all three new subnets.

Explanation

In this scenario, a third Availability Zone (AZ) has become available, and the solutions architect wants to adopt it without adding additional IPv4 address space and without service downtime. To meet these requirements, the following steps can be taken: Update the Auto Scaling group to use the AZ2 subnet only. Delete and re-create the AZ1 subnet using half the previous address space. Adjust the Auto Scaling group to also use the new AZ1 subnet. When the instances are healthy, adjust the Auto Scaling group to use the AZ1 subnet only. Remove the current AZ2 subnet. Create a new AZ2 subnet using the second half of the address space from the original AZ1 subnet. Create a new AZ3 subnet using half the original AZ2 subnet address space. Update the Auto Scaling group to target all three new subnets. This approach ensures that existing resources continue to function as expected while also accommodating new resources in a way that doesn't interfere with existing ones. Option B suggests terminating the EC2 instances in the AZ1 subnet, which may cause service downtime. Option C suggests creating a new VPC, which is not necessary in this scenario and will require significant reconfiguration. Option D has a similar approach but deviates by updating the current AZ2 subnet, which is not necessary and may cause service downtime. "It's not possible to modify the IP address range of an existing virtual private cloud (VPC) or subnet. "