AWS Certified Advanced Networking Specialty Practice Exam

For maintaining high availability, how many subnets should be created for web and database servers in a VPC?

1. 1

2. 2

3. 3

4. 4

The correct answer is: 4

For maintaining high availability in a Virtual Private Cloud (VPC) environment, it is essential to distribute instances across multiple Availability Zones (AZs). Each AZ in a region is designed to be isolated from failures in other AZs, which enhances the resilience of your applications. Creating four subnets, ideally two in each of two different Availability Zones, provides a robust architecture. This setup allows for load balancing between servers and ensures that if one AZ goes down, the instances in the other AZ can continue to serve traffic, minimizing downtime. By utilizing multiple subnets in different AZs for both web and database servers, you can implement redundancy and fault tolerance, which are critical for maintaining high availability in a cloud infrastructure. Additionally, distributing databases across different subnets can also provide improved performance and scalable solutions like read replicas. In contrast, fewer subnets increase the risk of a single point of failure and do not leverage the AWS framework designed for high availability. Thus, having four subnets strategically defined in two separate AZs stands out as the optimal approach for achieving high availability in a VPC.