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CLF-018
Which of the following is the most appropriate description of Amazon EC2?
Choices
Explanation and answer
Read the explanation and correct answer (spoiler — try answering first)
Correct answer: B. A service that lets you launch virtual servers on AWS.
Explanation
Amazon EC2 is a service that lets you launch virtual servers on AWS, and configure the operating system and middleware to use them.
Per-choice explanations
A. An object storage service.
Incorrect. Object storage is Amazon S3.
B. A service that lets you launch virtual servers on AWS.
Correct. EC2 is a virtual server service.
C. A DNS service.
Incorrect. DNS is Amazon Route 53.
D. A service that sends cost budget notifications only.
Incorrect. Budget notifications are handled by AWS Budgets.
Practical Use
Amazon EC2 (Elastic Compute Cloud) is an IaaS (Infrastructure as a Service) virtual server service provided by AWS. The user is responsible for installing, configuring, and managing the operating system, middleware, runtime, and application, while AWS handles the hardware and the virtualization layer (the hypervisor). Under the AWS Shared Responsibility Model, security in the cloud (the OS and above) is the responsibility of the user. The main ways EC2 is used include lift-and-shift migrations of existing on-premises servers to the cloud, building web servers, application servers, and database servers, batch processing servers, and training machine learning models. Billing is based on instance running time, measured by the second. While an instance is stopped, the EC2 instance charge does not apply, but attached Amazon EBS volumes (storage) continue to incur charges even when the instance is stopped. There are several purchase options that you choose based on your usage. On-Demand is the basic form where you use the instance by the hour for as long as you need it. Reserved Instances offer significant discounts in exchange for a one-year or three-year commitment. Savings Plans are an integrated discount option that applies commitment discounts similar to Reserved Instances flexibly across instance types. Spot Instances let you use spare AWS capacity at a market price for up to 90% off, but they can be interrupted at the discretion of AWS. Dedicated Hosts give you a physical server for your own use, and are used for bring-your-own-license (BYOL) support. On CLF-C02, this content is asked as a question that requests what service EC2 is, or which option is the virtual server. Distractors often include Amazon S3 (object storage), Amazon Route 53 (DNS), and AWS Budgets (budget management). From SAA-C03 onward, the combination with Auto Scaling Groups and Elastic Load Balancing, the AMI mechanism, the differences between security groups and Network ACLs, and the selection among purchase options are asked in depth.