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Difficulty: MediumAWS Pricing Models

An e-commerce company is launching a three-day promotional campaign. The web application, hosted on Amazon EC2, is expected to experience sudden, unpredictable traffic spikes during this period. The company requires that any newly launched instances to handle the peak traffic remain continuously active without interruption to ensure a seamless customer experience. Which Amazon EC2 pricing model is the most appropriate and cost-effective for these temporary scaling instances?

  1. On-Demand InstancesAnswer
  2. B
    Spot Instances
  3. C
    Reserved Instances
  4. D
    Dedicated Hosts

Answer

On-Demand Instances
On-Demand Instances are the most appropriate choice because they require no upfront payment or long-term commitment, can scale dynamically to handle unpredictable spikes, and guarantee that the instances will not be interrupted by AWS. This makes them ideal for short-term, spiky, and critical workloads.

Step-by-Step Solution

1
Analyze the workload requirements
The workload is short-term (three days), unpredictable (spiky traffic), and requires uninterrupted availability (no interruptions allowed).
Understanding the timeline and tolerance for interruption determines which EC2 pricing models are viable.
2
Evaluate the suitability of Spot Instances
Spot Instances can be interrupted with a two-minute warning, which violates the requirement for uninterrupted availability.
AWS can reclaim Spot capacity at any time, making them unsuitable for critical user-facing web applications.
3
Evaluate the suitability of Reserved Instances or Savings Plans
These models require a minimum of a one-year commitment, which is highly inefficient for a three-day event.
Long-term commitments are not cost-effective for extremely short-term scaling needs.
4
Determine the most cost-effective and appropriate option
On-Demand Instances provide uninterrupted capacity with a pay-as-you-go model and no long-term commitment, matching all requirements.
On-Demand matches the requirement for continuous availability and zero long-term commitment for temporary scaling.

Key Concept

Selecting the optimal Amazon EC2 pricing model based on workload duration, predictability, and fault tolerance.
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Topics

AWS Pricing Models

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