Purchasing Options

Question 1

On-Demand Instances

Answer 1

Pay for what you use:
- Linux or Windows - billing per second, after the first minute
- All other operating systems - billing per hour

Has the highest cost but no upfront payment

No long-term commitment

Recommended for short-term and un-interrupted workloads, where you can’t predict how the application will behave

Question 2

Reserved

Answer 2

• Reservation Period - 1 year or 3 years
• Payment Options - No Upfront, Partial Upfront, All Upfront
• Reserved Instance’s Scope - Regional or Zonal
• Recommended for steady-state usage applications (think database)
• You can buy and sell in the Reserved Instance Marketplace

Convertible Reserved Instance:
- Can change the EC2 instance type, instance family, OS, scope and tenancy

Question 3

Savings Plans

Answer 3

• Get a discount based on long-term usage
• Commit to a certain type of usage ($10/hour for 1 or 3 years)
• Usage beyond EC2 Savings Plan is billed at the On-Demand price
• Locked to a specific instance family & AWS region

Flexible across:
- Instance Size
- OS
- Tenancy

Question 4

Spot Instances

Answer 4

Instances can lose at any point of time if your max price is less than the current spot price

The most cost-efficient instances in AWS

Useful for workloads that are resilient to failure
- Batch jobs
- Data analysis
- Image processing
- Any distributed workloads
- Workloads with a flexible start and end time

Not suitable for critical jobs or databases

Question 5

Dedicated Hosts

Answer 5

Physical server with EC2 instance capacity fully dedicated to your use

Allows you address compliance requirements and use your existing server-bound software licenses (per-socket, per-core, per-VM software licenses)

Purchasing Options:
- On-demand - pay per second for active Dedicated Host
0 Reserved - 1 or 3 years (No Upfront, Partial Upfront, All Upfront)

The most expensive option

Useful for software that have complicated licensing model (BYOL - Bring Your Own License)

Or for companies that have strong regulatory or compliance needs

Question 6

Dedicated Instances

Answer 6

Instances run on hardware that’s dedicated to you

May share hardware with other instances in same account

No control over instance placement (can move hardware after Stop / Start)

No other customers will share your hardware

Question 7

Capacity Reservations

Answer 7

Reserve On-Demand instances capacity in a specific AZ for any duration

You always have access to EC2 capacity when you need it

No time commitment (create/cancel anytime), no billing discounts

Combine with Regional Reserved Instances and Savings Plans to benefit from billing discounts

You’re charged at On-Demand rate whether you run instances or not

Suitable for short-term, uninterrupted workloads that need to be in a specific AZ