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These AWS interview questions will help you prepare for your next Amazon Web Services interview. Whether you are a seasoned software engineer, or just learning the basics of cloud computing, these questions should have you covered. If you are an engineer just beginning to learn about AWS, start with the first question, and try to get through as many as possible before moving on to the next set of questions.

What is AWS?

Amazon Web Services (AWS) is a web-based software service which stores information online. It's an online service where users can deploy, manage, and scale any type of application - without managing any servers themselves. AWS offers three broad categories of service in infrastructure as follows: Compute services, storage services, and content delivery network (CDN) services. 

1) What are the components of AWS? ·

 EC2 – Elastic Compute Cloud · AMI – A virtual machine for use with EC2 that runs Linux. · S3 – Simple Storage Service · RDS – Relational Database Service · EBS – Elastic Block Store · ELB-Elastic Load Balancer · VPC-Virtual Private Cloud 

2) What are Key-pairs? · 

Two sets of keys to access and control data. One set is private and known only to you, while the other set is public but limited in its capabilities so it can be shared among multiple people.

Components of AWS

AWS includes a broad set of services for compute, storage, databases, analytics, deployment and many more. AWS also provides security and developer tools that are required to build applications in the cloud. Key-pairs allow users to securely transfer data from one AWS account to another by using public-private encryption keys. S3 is an object storage service where you can store anything such as web pages, images or videos in buckets that are both highly durable and scalable. Data stored on S3 can be retrieved via RESTful API, Amazon S3 console, command line interface (CLI) or third party software libraries. 

The pricing models vary depending on the type of EC2 instance you purchase. There are three different ways to pay for your instances: On Demand - with this option, customers will be charged hourly based on the amount of CPU time consumed; Reserved Instances - with this option, customers will make a single upfront payment and then receive significant discounts; Spot Instances - with this option customers bid against other spot instance buyers for unused capacity.

Key Pairs

Once you have your account set up, the next step is to create a key-pair. A key-pair is a way of protecting your Amazon Web Services account with two pieces of information that only you should know. This ensures that you are the only person who can access any files or data saved within AWS services.

The first thing to do is generate and download a key-pair from the Amazon Management Console. Make sure it’s named and stored in a place where only you will find it! Next, copy the private key file and save it in another folder that's password protected on your computer to make sure it’s safe from anyone else. Once this has been done, delete this folder from view for good measure, but don't delete the file itself!

S3 (Storage Solution)

Amazon S3 is a cloud storage solution that can be used to store and distribute any type of data, from videos to static web pages. To protect your data, S3 encrypts it on the client before sending it to the Amazon S3 server. In addition, Amazon manages the underlying infrastructure for you so you don't have to worry about up-keeping your own server or software.

 AWS offers many different levels of performance and durability, so customers can select the option that best suits their requirements. Amazon currently stores over 150 billion objects in S3! If each object was printed as an A4 sheet of paper, they would cover an area greater than all of Central Park.

Elastic Compute Cloud(EC2)

EC2 instances come in two major categories, On-Demand and Reserved Instances. Amazon EC2 can be billed per second, hour, day, week or month. For example, if you sign up for a Basic instance (32 GB memory) you'll pay $0.074/hour and this price does not fluctuate with the market price of the service; however, if you are using a High Memory Reserved Instance (1488GB memory), your hourly rate will be significantly higher but also follows hourly fluctuations as seen in AWS's Reserved Instance Price History chart here.

 When signing up for an on-demand instance, you may want to consider buying a prepaid block of hours to reduce your monthly costs since Amazon charges by the hour. If you choose to do so, your cost is calculated by multiplying the total number of hours in a block by the hourly rate for that type of instance. For example, if you purchase 100 hours at $0.074/hour then your cost would be ($7.40).

Pricing Models

The pricing models for EC2 are based on on-demand and reserved instances. Instances are billed hourly, so you pay a fraction of the cost for each hour your instance is running. You can also reduce costs by turning off your instance when it's not in use. AWS provides a service called Elastic Block Storage (EBS) which enables the deployment of ephemeral storage that is provisioned within minutes. Ephemeral storage can be configured to be persistent or non-persistent (i.e., virtual machine snapshots). 

In order to create an Amazon EBS volume that persists beyond the life of its associated EC2 instance, customers must make sure they have enough free space available in their AWS account to store this data - otherwise data may be lost if there isn't enough space available to store it all. 

The pricing model for EBS volumes depends on whether you need block level storage or file level storage.