Which EC2 purchasing option fits steady, predictable 1-year traffic?
An online gaming company needs to choose a purchasing option to run its Amazon EC2 instances for 1 year. The web traffic is consistent, and any increases in traffic are predictable. The EC2 instances must be online and available without any disruption. Which EC2 instance purchasing option will meet these requirements MOST cost-effectively?
Community Insight
The test is separating "predictable, must-not-be-interrupted, fixed 1-year term" from interruptible bargain hunting — the trap is picking Spot because it is cheapest on paper.
This question tests how to match an Amazon EC2 purchasing option to a steady, predictable workload that must stay online for one year. Reserved Instances are the most cost-effective choice because the one-year commitment earns a large discount without any interruption risk.
The most common wrong answer is Spot Instances (or a Spot Fleet) because they carry the deepest discount, but Spot capacity can be reclaimed with a two-minute warning, which violates the requirement that the gaming servers stay online without disruption.
Community Discussion (19 comments)
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Expert Analysis
Why the Answer Is Correct
Reserved Instances are the right fit because every constraint in the scenario points to them: the web traffic is consistent, any spikes are predictable, and the company already knows it needs the EC2 capacity for one year. Committing to a one-year term converts that certainty into a significant discount versus On-Demand pricing, while the instances remain dedicated to the account and are never interrupted. As Anyio noted, RIs offer "a significant discount (up to 72%) compared to On-Demand pricing" and can also provide a capacity reservation in a specific Availability Zone. Nothing in the requirements demands the flexibility of Savings Plans beyond the instance family, and no interruption is acceptable, so the reservation model is the most cost-effective safe option.Why the Other Options Are Wrong
On-Demand Instances preserve flexibility but are the most expensive way to run a workload the company already knows it will keep for twelve months, so they fail the "MOST cost-effectively" test. Spot Instances and Spot Fleet offer the largest discounts, but Spot capacity is spare Amazon EC2 capacity that can be reclaimed at short notice — unacceptable for a live game backend that must stay online without disruption. A Spot Fleet is simply a collection of Spot and optionally On-Demand instances, so it inherits the same interruption exposure. As lunamuller summarized, the deciding clues are "instance for 1 year", "traffic is predictable" and "available without any disruption".Community Comment Notes
Consensus among commenters is strongly behind Reserved Instances, with Sir_Kay emphasizing that committing to a one-year term can save "up to 75% compared to On-Demand pricing" for predictable traffic, and parrtner73 reducing the logic to "predictable, long term". Ruffyit, TheFivePips and Buda all walk through the same elimination: On-Demand is pay-as-you-go and less cost-effective for consistent workloads, while RIs are suited to consistent, predictable demand. Abhi_2005 raised a side point about Savings Plans versus RIs and their term constraints, which does not change the answer here because Reserved Instances are the option offered that best matches a fixed one-year, non-interruptible commitment.Official Reference
Exam Strategy
Scan the stem for three signals: a fixed term (1 year), predictable/steady demand, and a no-disruption requirement. Those three together map to Reserved Instances; reserve Spot for fault-tolerant, interruptible batch work and On-Demand for short-lived or unpredictable workloads.
Frequently Asked Questions
Why are Spot Instances wrong for a gaming backend that must stay online?
Spot capacity is spare EC2 capacity that AWS can reclaim with a short interruption notice, so it cannot guarantee uninterrupted availability for a live game.
Would On-Demand Instances ever be a better fit than Reserved Instances here?
Only if the workload were short-lived or unpredictable. With a known one-year need and steady traffic, On-Demand costs more than a one-year Reserved Instance commitment.
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