Design Considerations for Low Latency in AWS Application

Answer - D.

Options A and C are INCORRECT because these would provide only high availability and not low latency.

Options B is incorrect because using multiple instances would not guarantee low latency.

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To achieve low latency between instances that support the application, you have multiple options:

A. Deploy instances across multiple availability zones: Deploying instances across multiple availability zones is a good approach to achieve high availability and fault tolerance. But deploying instances across multiple availability zones does not guarantee low latency between instances. Instances deployed in different availability zones are physically separated, and the distance between them may result in higher network latency. Therefore, this option may not be the best choice if low latency is a critical requirement.

B. Use multiple instances: Using multiple instances can improve the application's performance and can help to distribute the load across the instances. But using multiple instances alone may not guarantee low latency between the instances. Multiple instances still need to communicate with each other, and the network latency between them can impact the overall latency of the application.

C. Use a Network Load Balancer in front of the instances: Using a Network Load Balancer (NLB) in front of the instances can help to distribute the traffic evenly across the instances and can help to achieve low latency between the instances. The NLB uses intelligent routing algorithms to distribute traffic to the instances based on the traffic type and the instance's load. The NLB can help to reduce the network latency by selecting the closest instance to handle the request.

D. Place the instances in a cluster placement group: A cluster placement group is a logical grouping of instances within a single Availability Zone. When instances are placed in a cluster placement group, they are placed in close proximity to each other, which can help to achieve low latency between the instances. A cluster placement group can help to achieve low latency for applications that require high network throughput, low network latency, or both.

Therefore, the best option to achieve low latency between instances that support the application would be to use a Network Load Balancer in front of the instances or to place the instances in a cluster placement group.