← SOA-C02·Amazon Web Services

Question 339 of 1,546

Cost and Performance Optimization →easyMultiple SelectObjective-mapped

EC2 Cost Optimization for Interruptible Batch Jobs with Spot and Scheduled Reserved Instances

This SOA-C02 practice question tests your understanding of cost and performance optimization. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: spot Instances. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Which TWO actions can reduce costs for an Amazon EC2 environment that runs non-critical batch jobs that can be interrupted? (Choose TWO.)

A
Use Scheduled Reserved Instances.
Why wrong: Incorrect. Scheduled Reserved Instances are for predictable, recurring workloads that run on a fixed schedule, not for interruptible batch jobs. They require a 1-year commitment and do not offer interruption tolerance.
B
Associate Elastic IP addresses with the instances.
Why wrong: Incorrect. Elastic IP addresses are static public IPv4 addresses; they do not reduce costs. In fact, they can incur charges if not associated with a running instance.
C
Use Dedicated Hosts.
Why wrong: Incorrect. Dedicated Hosts provide physical servers dedicated for your use, which is more expensive than shared tenancy. They do not provide cost savings for interruptible batch jobs.
D
Use Spot Instances for the batch jobs.
Correct. Spot Instances offer significant cost savings for interruptible workloads, as they can be terminated by AWS when capacity is needed elsewhere. They are ideal for non-critical batch jobs.
E
Use On-Demand Instances.
Why wrong: Incorrect. On-Demand Instances are pay-as-you-go and charge full price without any discount, making them more expensive than Spot Instances for interruptible workloads.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Use Spot Instances for the batch jobs.

Spot Instances are ideal for interruptible workloads because they offer substantial discounts (up to 90%) compared to On-Demand pricing. They can be interrupted with a two-minute notice, making them suitable for non-critical batch jobs that can tolerate interruptions. Scheduled Reserved Instances, on the other hand, are designed for predictable, steady-state workloads that run on a recurring schedule; they do not provide interruption tolerance and are not cost-effective for interruptible workloads.

Key principle: Spot Instances

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Use Scheduled Reserved Instances.
Why it's wrong here
Incorrect. Scheduled Reserved Instances are for predictable, recurring workloads that run on a fixed schedule, not for interruptible batch jobs. They require a 1-year commitment and do not offer interruption tolerance.
✗
Associate Elastic IP addresses with the instances.
Why it's wrong here
Incorrect. Elastic IP addresses are static public IPv4 addresses; they do not reduce costs. In fact, they can incur charges if not associated with a running instance.
✗
Use Dedicated Hosts.
Why it's wrong here
Incorrect. Dedicated Hosts provide physical servers dedicated for your use, which is more expensive than shared tenancy. They do not provide cost savings for interruptible batch jobs.
✓
Use Spot Instances for the batch jobs.
Why this is correct
Correct. Spot Instances offer significant cost savings for interruptible workloads, as they can be terminated by AWS when capacity is needed elsewhere. They are ideal for non-critical batch jobs.
Related concept
Spot Instances
✗
Use On-Demand Instances.
Why it's wrong here
Incorrect. On-Demand Instances are pay-as-you-go and charge full price without any discount, making them more expensive than Spot Instances for interruptible workloads.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap is that candidates may think Scheduled Reserved Instances are appropriate for interruptible batch jobs because they offer a discount, but they are actually intended for predictable, continuous usage. For workloads that can be interrupted, Spot Instances are the correct choice.

Detailed technical explanation

How to think about this question

Spot Instances leverage AWS's spare EC2 capacity and can offer up to 90% discount compared to On-Demand pricing, but they can be terminated with a 2-minute warning when capacity is reclaimed. Scheduled Reserved Instances are purchased for a 1-year term and are ideal for predictable, recurring batch windows; they do not support interruption but provide a fixed discount for those specific time slots. Combining both allows you to run batch jobs at the lowest possible cost while tolerating potential interruptions.

KKey Concepts to Remember

Spot Instances
Interruptible Workloads

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Spot Instances

Real-world example

How this comes up in practice

A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.

What to study next

Got this wrong? Here's your next step.

Review spot Instances, then practise related SOA-C02 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this SOA-C02 question test?

Cost and Performance Optimization — This question tests Cost and Performance Optimization — Spot Instances.

What is the correct answer to this question?

The correct answer is: Use Spot Instances for the batch jobs. — Spot Instances are ideal for interruptible workloads because they offer substantial discounts (up to 90%) compared to On-Demand pricing. They can be interrupted with a two-minute notice, making them suitable for non-critical batch jobs that can tolerate interruptions. Scheduled Reserved Instances, on the other hand, are designed for predictable, steady-state workloads that run on a recurring schedule; they do not provide interruption tolerance and are not cost-effective for interruptible workloads.

What should I do if I get this SOA-C02 question wrong?

Review spot Instances, then practise related SOA-C02 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

Spot Instances

About these practice questions

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Same concept, more angles

1 more ways this is tested on SOA-C02

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A SysOps administrator is managing a fleet of Amazon EC2 instances that run a batch processing job. The job runs for 30 minutes every hour. The administrator wants to optimize costs by using Spot Instances but must ensure that the job completes even if Spot Instances are interrupted. Which configuration should the administrator use?

medium

A.Launch Spot Instances in an Auto Scaling group with a capacity-optimized allocation strategy.
✓ B.Use a mixed instances policy with both On-Demand and Spot Instances, and configure the Spot allocation strategy to 'lowestPrice'.
C.Use a Spot Fleet with a 'persistent' request type.
D.Use only On-Demand Instances to avoid interruptions.

Why B: Option B is correct because a mixed instances policy with both On-Demand and Spot Instances provides a safety net: the On-Demand capacity ensures the job can continue even if Spot Instances are interrupted. The 'lowestPrice' allocation strategy optimizes cost by selecting the cheapest Spot Instances, and since the job runs for only 30 minutes each hour, the risk of interruption is low and any interruption can be absorbed by the On-Demand instances. This configuration balances cost savings with job completion guarantees.

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