ANS-C01 Question 422
Select 3You are designing a VPC for a new application that requires high availability and scalability across multiple Availability Zones (AZs). The application will have public-facing components (e.g., an Application Load Balancer) and private backend services (e.g., EC2 instances and a database). Which of the following design considerations will optimize the VPC subnet configuration for this use case?
- A
Create separate public and private subnets in each Availability Zone to isolate resources.
- B
Use a single large subnet for all resources across all Availability Zones to simplify management.
- C
Allocate the public subnets for resources that require internet access, and associate them with an internet gateway.
- D
Ensure all private subnets are associated with a NAT gateway deployed in only one Availability Zone to reduce costs.
- E
Design subnet CIDR blocks to accommodate future growth and avoid overlapping IP ranges.
Show answer and explanation
Correct answers: A, C, E
Explanation
Optimizing VPC subnet configurations requires careful consideration of resource isolation, high availability, and scalability. By creating separate public and private subnets in each AZ, you ensure resource isolation and fault tolerance. Allocating public subnets for internet-facing resources while using NAT gateways for private subnets ensures secure access to and from the internet. Additionally, planning CIDR blocks for future growth prevents potential IP conflicts as the application scales. Avoiding single points of failure, such as deploying a NAT gateway in only one AZ, is critical for maintaining high availability.
- A. Correct.
Correct: Creating separate public and private subnets in each Availability Zone ensures resource isolation and supports high availability by distributing workloads across multiple AZs.
- B. Incorrect.
Incorrect: Using a single large subnet across all AZs is not recommended because it does not provide resource isolation or high availability, and it can lead to IP conflicts.
- C. Correct.
Correct: Allocating public subnets for internet-facing resources and associating them with an internet gateway ensures that only public resources can access or be accessed from the internet.
- D. Incorrect.
Incorrect: Associating private subnets with a NAT gateway deployed in only one AZ creates a single point of failure. For high availability, NAT gateways should be deployed in multiple AZs.
- E. Correct.
Correct: Designing CIDR blocks to accommodate future growth and avoid overlaps is essential for scalability and to prevent routing issues.