Free CLF-C02 practice questions: EC2 & S3 fundamentals

Amazon EC2 and Amazon S3 are the two services the CLF-C02 mentions more than any others, and they anchor the Cloud Technology and Services domain — the biggest domain on the exam at 34%. You do not need to configure either one to pass. You need to know what each is, and to keep a few sharp distinctions straight that the exam deliberately blurs.

EC2: a server you control

EC2 gives you a virtual server in the cloud. You pick the instance type — a combination of CPU, memory and network capacity — and you control the operating system: you can install software, open ports and log in. That control is the whole point, and it is also what separates EC2 from everything more managed. If a question describes needing OS-level access or a specific runtime you must install yourself, EC2 is the answer; if it describes wanting to avoid managing servers, EC2 is the wrong answer and something like Lambda or a managed service is right.

Two supporting ideas come up. An AMI (Amazon Machine Image) is the template an instance boots from — the OS plus any baked-in configuration. And EC2 is resizable: you can change instance size, and you can run one or a thousand instances. The exam treats EC2 as the default “I need a computer in the cloud” service.

The storage fork the exam loves: EBS vs instance store

An EC2 instance needs disk. There are two kinds, and telling them apart is a reliable exam point:

• Amazon EBS is a network-attached block volume. Its life is independent of the instance — stop the instance and the data is still there. Use it for anything that must persist: boot volumes, databases, files you cannot lose.
• Instance store is physically attached, fast, and temporary. Stop the instance and the data is gone. It is for scratch data, caches, anything you can rebuild.

The trap is always the same: a scenario where data “must not be lost” paired with an instance store option. If persistence matters, the answer is EBS.

S3: objects, not disks

Amazon S3 is object storage. You create a bucket and put objects (files) in it, and you reach them over the internet. It scales to any amount of data, it is highly durable, and there is no instance in the picture — which is exactly why it is wrong whenever a question needs OS access, and right whenever a question needs to store or serve files cheaply. S3 can even host a static website directly.

Where S3 gets tested is storage classes, and you only need the shape of the spectrum, not the price list:

• S3 Standard — frequently accessed data, highest cost, instant access.
• S3 Standard-Infrequent Access — accessed rarely but instantly when needed, cheaper.
• S3 Glacier / Glacier Deep Archive — archival, lowest cost, retrieval measured in minutes to hours.
• S3 Intelligent-Tiering — moves objects between tiers for you when the access pattern is unknown.

Match the class to how often the data is touched and how fast it must come back. That is the entire question.

How to use the questions below

Answer each one before you open the explanation, and when you are wrong, read past the correct letter to the part that says why the other three fail. On EC2 and S3 the distractors are always real, sensible services — EBS beside instance store, Glacier beside Standard — and the exam is checking whether you can separate them on sight, not whether you have heard the names.