3th of 4 Questions.
What are EC2 capacity reservations?
Understanding EC2 Capacity Reservations
An EC2 Capacity Reservation allows you to reserve compute capacity for your EC2 instances in a specific Availability Zone for any duration. This guarantees that AWS will have the capacity available when you need to launch your instances, regardless of overall region demand.
Key Characteristics
Guarantee: Ensures capacity availability in a specific AZ for a specific instance type.
Usage: Capacity is reserved regardless of whether you have instances running.
Billing: You are charged for the reserved capacity whether you use it or not.
Flexibility: Can be used in conjunction with Savings Plans and Reserved Instances to optimize costs.