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AWS Interview Questions
Snowball is a transporting option available in AWS to transport the data in and out of AWS. Snowball helps to transfer immense data at low networking cost.
Key Pairs are used to connect to the virtual machines. The secure login credentials used to connect to virtual machines are known as Key pairs.
There are mainly three kinds of cloud service types that AWS products offer. These are:
Computing : Auto-scaling, EC2, Lightsat, Elastic Beanstalk, and Lambda

Storage :
S3, Elastic File System, Elastic Block Storage, and Glacier

Networking :
VPC, Route53, and Amazon CloudFront
Auto Scaling is a feature in aws that automatically scales the capacity to maintain steady and predictable performance. While using auto scaling, you can scale multiple resources across multiple services in minutes. If you are already using Amazon EC2 Auto- scaling, then you can combine Amazon EC2 Auto-Scaling with the Auto-Scaling to scale additional resources for other AWS services.
Benefits of Auto Scaling
Setup Scaling Quickly : It sets the target utilization levels of multiple resources in a single interface. You can see the average utilization level of multiple resources in the same console, i.e., you do not have to move to the different console.

Make Smart Scaling Decisions : It makes the scaling plans that automate how different resources respond to the changes. It optimizes the availability and cost. It automatically creates the scaling policies and sets the targets based on your preference. It also monitors your application and automatically adds or removes the capacity based on the requirements.

Automatically maintain performance : Auto Scaling automatically optimize the application performance and availability even when the workloads are unpredictable. It continuously monitors your application to maintain the desired performance level. When demand rises, then Auto Scaling automatically scales the resources.
Regions : A region is a geographical area which consists of 2 or more availability zones. A region is a collection of data centers which are completely isolated from other regions.
Availability zones : An Availability zone is a data center that can be somewhere in the country or city. Data center can have multiple servers, switches, firewalls, load balancing. The things through which you can interact with the cloud reside inside the Data center.
Geo-targeting in the CloudFront supports the creation of customized content for a  target audience as suggested by demand and the needs of a specific geographical area. This helps businesses showcase their personalized content to the target audience in different geographic locations without changing its URL.
There are four steps involved in CloudFront. These are :
Step 1 : Creating a CloudFormation template in YAML or JSON format

Step 2 :
Saving the code in an S3 bucket so that it serves the repository for the code

Step 3 :
Using the AWS CloudFormation to call the bucket and thereby creating a new stack on the template

Step 4 :
CloudFormation reads the file and thus understands the services required that are called along with their order details, relationships with services and associated provisions
The main differences between ‘horizontal’ and ‘vertical’ scales are :


Horizontal Scale

Vertical Scale

Provides new resources along with new hardware devices to support the infrastructure

You would need to increase power resources by upgrading the current machine

Used in distributed systems

Used in virtualization

Resilient to system failure 

Single point of failure

Utilizes network calls

Interprocess communication

Increases the capacity of existing hardware or software by adding additional resources

Connects multiple system entities, both hardware, and software such that they work as a single logical unit

Difficult to implement 

Easy to implement

Geo-Targeting is a concept where businesses can show personalized content to their audience based on their geographic location without changing the URL. This helps you create customized content for the audience of a specific geographical area, keeping their needs in the forefront.
You can upgrade or downgrade a system with near-zero downtime using the following steps of migration:
* Open EC2 console
* Choose Operating System AMI
* Launch an instance with the new instance type
* Install all the updates
* Install applications
* Test the instance to see if it’s working
* If working, deploy the new instance and replace the older instance
* Once it’s deployed, you can upgrade or downgrade the system with near-zero downtime.