AWS EC2 Interview Guide: 20 Key Questions and Expert Answers

1. What is Amazon EC2?
   Amazon Elastic Compute Cloud (EC2) is a web service that provides resizable compute capacity in the cloud. It is designed to make web-scale cloud computing easier for developers.

2. What is an EC2 instance?
   An EC2 instance is a virtual server in Amazon's Elastic Compute Cloud (EC2) for running applications on the AWS infrastructure.

3. What are the different types of EC2 instances?
   There are several types of EC2 instances, including General Purpose, Compute Optimized, Memory Optimized, Storage Optimized, and Accelerated Computing.

4. How is an EC2 instance billed?
   EC2 instances are billed on a per-second basis, with a minimum charge of one minute.

5. How do you launch an EC2 instance?
   You can launch an EC2 instance using the AWS Management Console, AWS CLI, or AWS SDKs.

6. What is an Amazon Machine Image (AMI)?
   An Amazon Machine Image (AMI) is a pre-configured virtual machine image, which is used to create EC2 instances.

7. Can you launch multiple instances from one AMI?
   Yes, you can launch multiple instances from one AMI.

8. What is the security group in EC2?
   A security group is a virtual firewall that controls inbound and outbound traffic to an EC2 instance.

9. What is the difference between Elastic IP and Public IP in EC2
   An Elastic IP is a static, public IP address that can be associated with an EC2 instance, whereas a Public IP is a dynamic IP address that is assigned to an instance at launch.

10. What is the difference between on-demand and spot instances in EC2?
    On-demand instances are charged at a fixed rate per hour, whereas spot instances are charged at a variable rate that fluctuates based on supply and demand.

11. What is Amazon EBS?
    Amazon Elastic Block Store (EBS) is a block-level storage service that is used to store persistent data for EC2 instances.

12. What is the difference between instance-store and EBS-backed instances?
    Instance-store instances use temporary storage that is physically attached to the host computer, whereas EBS-backed instances use EBS volumes for storage.

13. What is the purpose of an Amazon EBS snapshot?
    An Amazon EBS snapshot is a point-in-time copy of an EBS volume that can be used to create new volumes or restore data.

14. What is the Amazon EC2 Auto Scaling service?
    Amazon EC2 Auto Scaling is a service that automatically adjusts the number of EC2 instances in a group based on demand.

15. What is an Elastic Network Interface (ENI)?
    An Elastic Network Interface (ENI) is a virtual network interface that can be attached to an EC2 instance.

16. What is an EC2 Placement Group?
    An EC2 Placement Group is a logical grouping of instances that are placed within a single Availability Zone.

17. How can you monitor EC2 instances?
    You can monitor EC2 instances using Amazon CloudWatch, which provides metrics and logs for EC2 instances.

18. What is the difference between horizontal and vertical scaling
    Horizontal scaling involves adding more instances to a system, whereas vertical scaling involves increasing the size or capacity of an existing instance.

19. What is an Amazon Machine Image (AMI) ID?
    An Amazon Machine Image (AMI) ID is a unique identifier that is used to launch an EC2 instance.

20. What is AWS Elastic Beanstalk?
    AWS Elastic Beanstalk is a service that makes it easy to deploy, manage, and scale web applications in the AWS Cloud.

I hope these answers will help you prepare for your AWS EC2 interview.