Compute

Correct Answer: R5 instances

R5 instances are the best choice for memory-intensive applications on Amazon EC2. They are optimized for workloads that require high memory per vCPU and offer the lowest cost per GiB of RAM among EC2 instance types. C5 instances are optimized for compute-intensive workloads and do not prioritize memory. M5 instances provide a balance of resources but are not specifically optimized for memory-intensive applications. I3 instances are designed for I/O intensive workloads with high-speed NVMe SSD storage, but not necessarily for memory-intensive applications.

Correct Answer: Significant cost savings for workloads that can tolerate interruptions

The primary benefit of using Amazon EC2 Spot Instances is significant cost savings for workloads that can tolerate interruptions. Spot Instances allow you to bid on unused EC2 capacity at a discounted price, which can result in savings of up to 90% compared to On-Demand instances. However, Spot Instances can be interrupted by AWS with a two-minute notification when the Spot price exceeds your maximum bid price or when the capacity is no longer available. Therefore, they are suitable for fault-tolerant, flexible applications that can handle interruptions, such as batch processing, data analysis, or testing. The other options are incorrect because Spot Instances do not guarantee uninterrupted capacity, do not automatically scale based on metrics, and do not provide dedicated physical servers for exclusive use.

Correct Answer: Elastic Load Balancing

Elastic Load Balancing is the feature of Amazon EC2 that allows you to distribute incoming traffic across multiple instances in different Availability Zones. It automatically distributes incoming application traffic across multiple EC2 instances and can also distribute traffic across instances in multiple Availability Zones for high availability and fault tolerance. Auto Scaling groups can be used to automatically add or remove EC2 instances based on demand, but they do not distribute traffic on their own. Elastic IP addresses provide static IP addresses that can be dynamically remapped to different EC2 instances, but they do not distribute traffic. Virtual Private Cloud subnets allow you to create isolated networks within AWS, but they do not distribute traffic across instances.