Amazon AWS Interview Questions

What is AWS?

AWS (Amazon Web Services) is a platform to provide secure cloud services, database storage, offerings to compute power, content delivery, and other services to help business level and develop.

What is the importance of buffer in Amazon Web Services?

Buffer is used by elastic load balancer in order to synchronize the requests among various instances. The components are prone to work in an unstable way of receiving and processing the requests. So, the buffer is used to create equilibrium linking various apparatus and to provide identical rate among rapid services.

What is amazon VPC?

The Amazon Virtual Private Cloud (Amazon VPC) is Amazon's VPC offering that enables the development of virtual private cloud within the publicly available Amazon Web Services (AWS) cloud offerings.

Amazon VPC enables the development of a complete private cloud having its own policies & permissions, range of IP addresses, subnets, routes configuration and manage the entire resources, as they would have been in an in-house data centre.

The Amazon VPC is a private cloud within the AWS infrastructure, isolated logically with the public cloud products hosted on the same infrastructure.

Amazon VPC builds massive computing power through Amazon EC2, scalable storage via S3, and dedicated private IP address via Amazon Elastic IP. Amazon Elastic IP allocates separate IP addresses for each EC2 instance and isolates internet accessible & un-accessible servers so only desired servers are accessed by remote users. Amazon VPC can also be connected with an in-house VPN to create dedicated connection with the physical and cloud data centres.

What is AMI?

Amazon Machine Image is the full form of AMI.It is actually a template that provides the information of the operating system, server, applications etc., required to launch an instance that is the replica of the AMI running in the cloud as a virtual server.

What is Amazon EMR?

It is a survived cluster stage that interprets the working of data structures, before the intimation as Apache Hadoop and Apache Spark on the Amazon Web Services to investigate a large amount of data.We can prepare data for the analytics goals and marketing intellect workloads using Apache Huive and relevant open source designs.

Upon that, Amazon EMR can be used to migrate and convert the big masses of data into other AWS data repositories such as Amazon S3 and Amazon DynamoDB.

What is DynamoDB ?

This is the Amazon NoSQL database in the cloud that provides extremely high latency at any scale. It offers highly reliable service that is fully managed, has built-in security, in-memory caching, backup and restoration.

What is RDS?

This is the Amazon Relational Database Service. The Amazon RDS is a highly scalable relational database service. It offers a simple, cost-efficient database in the cloud that also automatically does database setup, hardware provisioning, backup and patching. Its advantages include high availability, fast performance, security and compatibility.

What is Amazon S3?

This is the Amazon Simple Storage. AWS S3 lets you seamlessly store and retrieve huge amounts of data anytime, anywhere through the web interface. It lets software developers to have access to data fast in an inexpensive, reliable and highly scalable manner. You can store all sorts of folders, files, and documents on the AWS S3.

What is scalabilty and flexibility?

Flexibility: Cloud computing allows your employees to be more flexible – both in and out of the workplace. Employees can access files using web-enabled devices such as smartphones, laptops and notebooks. The ability to simultaneously share documents and other files over the Internet can also help support both internal and external collaboration. Many employers are now implementing “bring your own device (BYOD)” policies. In this way, cloud computing enables the use of mobile technology.

Scalability: One of the key benefits of using cloud computing is its scalability. Cloud computing allows your business to easily upscale or downscale your IT requirements as and when required. For example, most cloud service providers will allow you to increase your existing resources to accommodate increased business needs or changes. This will allow you to support your business growth without expensive changes to your existing IT systems.

Mention the work of an Amazon VPC router?

Enabling of Amazon EC2 instances that is within the subnet so that it can communicate with Amazon EC2 instances on other subnets that are in the same VPC is done by an Amazon VPC router. It also helps in enabling Internet gateways, subnets, and virtual private gateways so that it can communicate with each other. You will not get between usage data from the router. But you are entitled to obtain network usage statistics from the instances which are using Amazon cloud watch.

Mention the process in which instances without public IP addresses access the Internet?

There are two ways in which instances without public addresses can make use of the Internet.

Those instances that are without public IP addresses can route their traffic through a NAT(network address translation) instance or a NAT gateway so that it can access the Internet. In order to traverse the Internet, these instances make use of public IP address of the NAT gateway or the NAT instance. Outbound communication is allowed by the NAT instance or NAT gateway but it do not permit machines on the Internet to start a connection with the addressed instances privately.

For those VPCs that are provided by a hardware VPN connection or direct connect connection, the instances can route the Internet traffic through the virtual private gateway to the existing data centre. It can then access the Internet through the existing egress points and also new tweak security or monitoring devices.

Mention the process in which a hardware VPN connection turns work with Amazon VPC?

The virtual private cloud is connected to the data centre with the help of a hardware VPN connection. Internet protocol security VPN connections are supported by Amazon. In order to intern the integrity and confidentiality of a data which is in transit, this data is transferred between the VPN and the data centres are routed over an encrypted VPN connection. To establish a hardware VPN connection you do not need an Internet gateway.

What is Amazon Simple Queue Service (SQS) ?

Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications. SQS eliminates the complexity and overhead associated with managing and operating message oriented middleware, and empowers developers to focus on differentiating work. Using SQS, you can send, store, and receive messages between software components at any volume, without losing messages or requiring other services to be available.

Differentiate between vertical and horizontal scaling in AWS?

The main difference between vertical and horizontal scaling is the way in which you add compute resources to your infrastructure. In vertical scaling, more power is added to the existing machine while in horizontal scaling additional resources are added into the system with the addition of more machines into the network so that the workload and processing is shared among multiple devices. The best way to understand the difference is imagine that you are retiring your Toyota and buying a Ferrari because you need more horsepower. This is vertical scaling. Another way to get that added horsepower is not to ditch the Toyota for the Ferrari but buy another car. This can be related to horizontal scaling where you drive several cars all at once.

When the users are up to 100, an EC2 instance alone is enough to run the entire web application or the database until the traffic ramps up. Under such circumstances when the traffic ramps up, it is better to scale vertically by increasing the capacity of the EC2 instance to meet the increasing demands of the application. AWS supports instances up to 128 virtual cores or 488GB RAM.

When the users for your application grow up to 1000 or more, vertical cannot handle requests and there is need for horizontal scaling which is achieved through distributed file system, clustering, and load balancing.

What is the total number of buckets that can be created in AWS by default ?

100 buckets can be created in each of the AWS accounts. If additional buckets are required, increase the bucket limit by submitting a service limit increase.

If you have half of the workload on public cloud while the other half is on local storage, what kind of architecture will you use for this ?

Hybrid Cloud Architecture: In cloud computing, hybrid cloud refers to the use of both on-premises resources in addition to public cloud resources. A hybrid cloud enables an organization to migrate applications and data to the cloud, extend their datacenter capacity, utilize new cloud-native capabilities, move applications closer to customers, and create a backup and disaster recovery solution with cost-effective high availability.

Differentiate between Spot Instances. An On-Demand instance or Reserved Instance?

Spot instances give the flexibility for purchasers to get reason capability with no direct commitment, at hourly rates typically less than the On-Demand rate in every region. Spot instances are similar to bidding; the bidding value is termed terms. The terms fluctuate supported provide and demand for instances. However, customers can never pay quite the utmost value they need nominal. If the spot moves on top of a customer’s most prices, the customer’s EC2 instance is going to be clean up mechanically. However, the reverse isn’t true, if the Spot costs come back down once more, your EC2 instance won’t launch mechanically, and one must do this manually.

In Spot and on-demand instance, there’s no commitment for the period from the user aspect, but in reserved instances, one must keep on with the fundamental measure that he has chosen.

What Is Amazon EC2 Auto Scaling?

Amazon EC2 Auto Scaling helps you ensure that you have the correct number of Amazon EC2 instances available to handle the load for your application. You create collections of EC2 instances, called Auto Scaling groups. You can specify the minimum number of instances in each Auto Scaling group, and Amazon EC2 Auto Scaling ensures that your group never goes below this size. You can specify the maximum number of instances in each Auto Scaling group, and Amazon EC2 Auto Scaling ensures that your group never goes above this size. If you specify the desired capacity, either when you create the group or at any time thereafter, Amazon EC2 Auto Scaling ensures that your group has this many instances. If you specify scaling policies, then Amazon EC2 Auto Scaling can launch or terminate instances as demand on your application increases or decreases.

For example, the following Auto Scaling group has a minimum size of one instance, a desired capacity of two instances, and a maximum size of four instances. The scaling policies that you define adjust the number of instances, within your minimum and maximum number of instances, based on the criteria that you specify.

Auto Scaling Components

The following table describes the key components of Amazon EC2 Auto Scaling.

Groups

Your EC2 instances are organized in to groups so that they can be treated as a logical unit for the purposes of scaling and management. When you create a group, you can specify its minimum, maximum, and, desired number of EC2 instances. For more information, see Auto Scaling Groups.

Configuration templates

Your group uses a launch template or a launch configuration as a configuration template for its EC2 instances. You can specify information such as the AMI ID, instance type, key pair, security groups, and block device mapping for your instances. For more information, see Launch Templates and Launch Configurations.

Scaling options

Amazon EC2 Auto Scaling provides several ways for you to scale your Auto Scaling groups. For example, you can configure a group to scale based on the occurrence of specified conditions (dynamic scaling) or on a schedule. For more information, see Scaling Options.

What are EBS volumes?

EBS stands for Elastic Block Stores. They are persistent volumes that you can attach to the instances. With EBS volumes, your data will be preserved even when you stop your instances, unlike your instance store volumes where the data is deleted when you stop the instances.

What is an EIP?

An Elastic IP address is a static IPv4 address designed for dynamic cloud computing. An Elastic IP address is associated with your AWS account. With an Elastic IP address, you can mask the failure of an instance or software by rapidly remapping the address to another instance in your account.

An Elastic IP address is a public IPv4 address, which is reachable from the internet. If your instance does not have a public IPv4 address, you can associate an Elastic IP address with your instance to enable communication with the internet; for example, to connect to your instance from your local computer.

What is Cloudwatch?

Cloudwatch is a monitoring tool that you can use to monitor your various AWS resources. Like health check, network, Application, etc.

There are 2 types in cloudwatch. Basic monitoring and detailed monitoring. Basic monitoring is free and detailed monitoring is chargeable.

What are policies and what are the types of policies?

Policies are permissions that you can attach to the users that you create. These policies will contain that access that you have provided to the users that you have created. There are 2 types of policies.

• Managed policies
• Inline policies

An AWS managed policy is a policy(standalone) that is created and administered by AWS.AWS managed policies make it easier for you to assign appropriate permissions to users, groups, and roles. if you had to write the policies yourself. You cannot change the permissions defined in AWS managed policies.

As a administer in your own AWS account you can create standalone policies which we refer to as customer managed policies.

An inline policy is a policy that's embedded in a principal entity (a user, group, or role)—that is, the policy is an inherent part of the principal entity. You can create a policy and embed it in a principal entity, either when you create the principal entity or later.

What are edge locations?

Edge location is the place where the contents will be cached. When a user tries to access some content, the content will be searched in the edge location. If it is not available then the content will be made available from the origin location and a copy will be stored in the edge location.

What are NAT gateways?

NAT stands for Network Address Translation. NAT gateways enables instances in a private subnet to connect to the internet but prevent the internet from initiating a connection with those instances.

What is SNS?

SNS stands for Simple Notification Service. SNS is a web service that makes it easy to notifications from the cloud. You can set up SNS to receive email notification or message notification.

What is and ELB?

ELB stands for Elastic Load balancing. ELB automatically distributes the incoming application traffic or network traffic across multiple targets like EC2, containers, IP addresses.

What is meant by subnet?

A subnet is a logical partition of an IP network into multiple, smaller network segments. It is typically used to subdivide large networks into smaller, more efficient subnetworks.

The internet is composed of many networks that are run by many organizations. In turn, each organization's network can be composed of many smaller networks, or subnets. Each subnet allows its connected devices to communicate with each other, and routers are used to communicate between subnets. The size of a subnet depends on the connectivity requirements and the network technology employed. A point-to-point subnet allows two devices to connect, while a data center subnet might be designed to connect many more devices.

How can you convert a public subnet to private subnet?

Remove IGW (Internet Gateway) & add NAT Gateway, Associate subnet in Private route table