Top AWS Interview questions and Answers in 2018

1.What is Amazon EC2 service?

Amazon Elastic Compute Cloud (Amazon EC2) is a Amazon web service that provides resizable (scalable) computing capacity in the cloud. You can use Amazon EC2 to launch as many virtual servers you need. In Amazon EC2 you can configure security and networking as well as manage storage. Amazon EC2 service also helps in obtaining and configuring capacity using minimal friction.

2. What is Amazon Machine Image (AMI)?

An Amazon Machine Image (AMI) is a template that contains a software configuration (for example, an operating system, an application server, and applications). From an AMI, we launch an instance, which is a copy of the AMI running as a virtual server in the cloud. We can even launch multiple instances of an AMI.

3. What is S3? What is it used for? Should encryption be used?

S3 stands for Simple Storage Service. You can think of it like FTP storage, where you can move files to and from there, but not mount it like a filesystem. AWS automatically puts your snapshots there, as well as AMIs there. Encryption should be considered for sensitive data, as AWS S3 is a proprietary technology developed by Amazon themselves, and as yet unproven vis-a-vis a security standpoint.

4. What automation tools can I use to spin up servers?

The most obvious way is to roll-your-own scripts, and use the AWS API tools. Such scripts could be written in bash, Perl or another language or your choice. The next option is to use a configuration management and provisioning tools like puppet or better it’s successor Opscode Chef. You might also look towards a tool like Scalr. Lastly, you can go with a managed solution such as Right scale.

5. How to use Amazon SQS?

Amazon SQS (Simple Queue Service) is a message passing mechanism that is used for communication between different connectors that are connected with each other. It also acts as a communicator between various components of Amazon. It keeps all the different functional components together. This functionality helps different components to be loosely coupled, and provide an AWS architecture that is more failure resilient system.

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6. Can I vertically scale an Amazon instance? How?

Yes. This is an incredible feature of AWS and cloud virtualization. Spin up a new larger instance than the one you are currently running. Pause that instance and detach the root ebs volume from this server and discard. Then stop your live instance, detach its root volume. Note down the unique device ID and attach that root volume to your new server. And then start it again. Voila, you have scaled vertically in-place!!

7. Explain Stopping, Starting, and Terminating an Amazon EC2 instance?

Stopping and Starting an instance: When an instance is stopped, the instance performs a normal shutdown and then transitions to a stopped state. All of its Amazon EBS volumes remain attached, and you can start the instance again at a later time. You are not charged for additional instance hours while the instance is in a stopped state.

Terminating an instance: When an instance is terminated, the instance performs a normal shutdown, then the attached Amazon EBS volumes are deleted unless the volume’s deleteOnTermination attribute is set to false. The instance itself is also deleted, and you can’t start the instance again at a later time.

8. What are the features of the Amazon EC2 service?

As the Amazon EC2 service is a cloud service so it has all the cloud features. Amazon EC2 provides the following features:

Virtual computing environment (known as instances)
Pre-configured templates for your instances (known as Amazon Machine Images – AMIs)
Amazon Machine Images (AMIs) is a complete package that you need for your server (including the operating system and additional software)
Amazon EC2 provides various configurations of CPU, memory, storage and networking capacity for your instances (known as instance type)
Secure login information for your instances using key pairs (AWS stores the public key and you can store the private key in a secure place)
Storage volumes of temporary data is deleted when you stop or terminate your instance (known as instance store volumes)
Amazon EC2 provides persistent storage volumes (using Amazon Elastic Block Store – EBS)
A firewall that enables you to specify the protocols, ports, and source IP ranges that can reach your instances using security groups
Static IP addresses for dynamic cloud computing (known as Elastic IP address)
Amazon EC2 provides metadata (known as tags)
Amazon EC2 provides virtual networks that are logically isolated from the rest of the AWS cloud, and that you can optionally connect to your own network (known as virtual private clouds – VPCs)

9. What is auto-scaling? How does it work?

Autoscaling is a feature of AWS which allows you to configure and automatically provision and spin up new instances without the need for your intervention. You do this by setting thresholds and metrics to monitor. When those thresholds are crossed, a new instance of your choosing will be spun up, configured, and rolled into the load balancer pool. Voila, you’ve scaled horizontally without any operator intervention!

10. When will you incur costs with an Elastic IP address (EIP)?

You are not charged, if only one Elastic IP address is attached with your running instance. But you do get charged in the following conditions:

When you use more than one Elastic IPs with your instance.
When your Elastic IP is attached to a stopped instance.
When your Elastic IP is not attached to any instance.

Top AWS Interview questions and Answers in 2018