Most popular aws interview questions

AWS most popular interview questions

1. What type of performance can you expect from Elastic Block Storage? How do you back it up and enhance the performance?

Performance of elastic block storage varies i.e. it can go above the SLA performance level and after that drop below it. SLA provides an average disk I/O rate which can at times frustrate performance experts who yearn for reliable and consistent disk throughput on a server. Virtual AWS instances do not behave this way. One can backup EBS volumes through a graphical user interface like elasticfox or use the snapshot facility through an API call. Also, the performance can be improved by using a Linux software raid and striping across four volumes.

2. Imagine that you have an AWS application that requires 24x7 availability and can be down only for a maximum of 15 minutes. How will you ensure that the database hosted on your EBS volume is backed up?

Automated backup is the key processes here as they work in the background without requiring any manual intervention. Whenever there is a need to back up the data, AWS API and AWS CLI play a vital role in automating the process through scripts. The best way is to prepare for a timely backup of EBS of the EC2 instance. The EBS snapshot should be stored on Amazon S3 and can be used for recovery of the database instance in case of any failure or downtime. 

3. You create a Route 53 latency record set from your domain to a system in Singapore and a similar record to a machine in Oregon. When a user located in India visits your domain, to which location will he be routed to?

Assuming that the application is hosted on Amazon EC2 instance and multiple instances of the applications are deployed on different EC2 regions. The request is most likely to go to Singapore because Amazon Route 53 is based on latency and it routes the requests based on the location that is likely to give the fastest response possible.

4. Differentiate between on-demand instance and spot instance.

Spot Instances are spare unused EC2 instances which one can bid for. Once the bid exceeds the existing spot price (which changes in real-time based on demand and supply) the spot instance will be launched. If the spot price becomes more than the bid price then the instance can go away anytime and terminate within 2 minutes of notice. The best way to decide on the optimal bid price for a spot instance is to check the price history of the last 90 days that is available on the AWS console. The advantage of spot instances is that they are cost-effective and the drawback is that they can be terminated anytime. Spot instances are ideal to use when –

• There are optional nice to have tasks.
• You have flexible workloads which can be run when there is enough compute capacity.
• Tasks that require extra computing capacity to improve performance.
On-demand instances are made available whenever you require them and you need to pay for the time you use them on an hourly basis. These instances can be released when they are no longer required and do not require any upfront commitment. The availability fo these instances is guaranteed by AWS unlike spot instances.
The best practice is to launch a couple of on-demand instances which can maintain a minimum level of guaranteed compute resources for the application and add-on few spot instances whenever there is an opportunity.

5. How will you access the data on EBS in AWS ?

Elastic block storage as the name indicates provides persistent, highly available and high-performance block-level storage that can be attached to a running EC2 instance. The storage can be formatted and mounted as a file system or the raw storage can be accessed directly.

DevOps Interview Question Set-1

DevOps Interview Question

1) What Service we should use when want to connect between private instance account A to private instance account B?

Options 
1) VPN 
2) VPC Peering
3) Internet gateway
4) All of Above

How to check python package version using pip

$ pip show <packege>

===========

$pip show boto3

Name: boto3

Version: 1.9.55

Summary: The AWS SDK for Python

Home-page: https://github.com/boto/boto3

Author: Amazon Web Services

Author-email: UNKNOWN

License: Apache License 2.0

Location: /Library/Python/2.7/site-packages

Requires: botocore, s3transfer, jmespath

Required-by: 

Installing and Configuring SSM Agent

AWS Systems Manager Agent (SSM Agent) is Amazon software that runs on your Amazon EC2 instances and your hybrid instances that are configured for Systems Manager (hybrid instances). SSM Agent processes requests from the Systems Manager service in the cloud and configures your machine as specified in the request. SSM Agent sends status and execution information back to the Systems Manager service by using the EC2 Messaging service. If you monitor traffic, you will see your instances communicating with ec2messages.* endpoints. For more information, see Reference: ec2messages, ssmmessages, and Other API Calls.

Starting with version 2.3.50.0 of SSM Agent, the agent creates a local user account called ssm-user and adds it to /etc/sudoers (Linux) or to the Administrators group (Windows) every time the agent starts. This ssm-user is the default OS user when a Session Manager session is started, and the password for this user is reset on every session. You can change the permissions by moving ssm-user to a less-privileged group or by changing the sudoers file. The ssm-user account is not removed from the system when SSM Agent is uninstalled.

SSM Agent is installed, by default, on the following Amazon EC2 Amazon Machine Images (AMIs):

• Windows Server (all SKUs)
• Amazon Linux
• Amazon Linux 2
• Ubuntu Server 16.04
• Ubuntu Server 18.04

You must manually install SSM Agent on Amazon EC2 instances created from other Linux AMIs. You must also manually install SSM Agent on servers or virtual machines in your on-premises environment. For more information, see Setting Up AWS Systems Manager in Hybrid Environments.

REFERENCE:- https://docs.aws.amazon.com/systems-manager/latest/userguide/ssm-agent.html

What is DevSecOps?

What is DevSecOps?

DevSecOps is the philosophy of integrating security practices within the DevOps process. DevSecOps involves creating a ‘Security as Code’ culture with ongoing, flexible collaboration between release DevOps engineers and security teams. The DevSecOps movement, like DevOps itself, is focused on creating new solutions for application development processes within an agile framework.

Now, in the collaborative framework of DevSecOps is a shared responsibility integrated from end to end. It’s a mindset that is so important,  “DevSecOps” to emphasize the need to build a secure foundation into DevOps initiatives.

DevOps isn’t just about development and operations teams. If you want to take full advantage of the agility and responsiveness of a DevOps approach, IT security must also play an integrated role in the full life cycle of your apps.

Why DevSecOps is important?

IT infrastructure has undergone huge changes in recent years. The shift to dynamic provisioning, shared resources, and cloud computing has driven benefits around IT speed, agility, and cost, and all of this has helped to improve application development.

“DevOps has become second nature for agile, high-performing enterprises and a foundation for the success of their online business,” says Pascal Geenens, a security evangelist and researcher at Radware.

“However, application security was most important, and at times perceived as a roadblock to staying ahead of the competition,” says Geenens. “Given the reliance of applications to keep operations running, bypassing security must be considered a high-risk strategy -- a distributed or permanent denial of service attack could easily catch you out.

          KEEP READING THIS SPACE FOR LATEST DEVSECOPS UPDATE

Application Load Balancer

Your Amazon ECS service can optionally be configured to use Elastic Load Balancing to distribute traffic evenly across the tasks in your service.

Elastic Load Balancing supports the following types of load balancers: Application Load Balancers, Network Load Balancers, and Classic Load Balancers, and Amazon ECS services can use either type of load balancer. Application Load Balancers are used to route HTTP/HTTPS (or Layer 7) traffic. Network Load Balancers and Classic Load Balancers are used to route TCP (or Layer 4) traffic. For more information, see Load Balancer Types.

Application Load Balancers offer several features that make them attractive for use with Amazon ECS services:

• Application Load Balancers allow containers to use dynamic host port mapping (so that multiple tasks from the same service are allowed per container instance).
• Application Load Balancers support path-based routing and priority rules (so that multiple services can use the same listener port on a single Application Load Balancer).

We recommend that you use Application Load Balancers for your Amazon ECS services so that you can take advantage of these latest features, unless your service requires a feature that is only available with Network Load Balancers or Classic Load Balancers. For more information about Elastic Load Balancing and the differences between the load balancer types, see the Elastic Load Balancing User Guide.

Reference details : 

https://docs.aws.amazon.com/AmazonECS/latest/developerguide/load-balancer-types.html

https://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-load-balancing.html

https://docs.aws.amazon.com/elasticloadbalancing/latest/userguide/

What is AWS CloudWatch ?

What is AWS CloudWatch?

Amazon CloudWatch is a monitoring service for AWS cloud resources and the applications you run on AWS. You can use Amazon CloudWatch to collect and track metrics, collect and monitor log files, set alarms, and automatically react to changes in your AWS resources. Amazon CloudWatch can monitor AWS resources such as Amazon EC2 instances, Amazon DynamoDB tables, and Amazon RDS DB instances, as well as custom metrics generated by your applications and services, and any log files your applications generate. You can use Amazon CloudWatch to gain system-wide visibility into resource utilization, application performance, and operational health. You can use these insights to react and keep your application running smoothly.