AWS Interview Questions and Answers

Question: What are different http status code?

    [100] => Continue
    [101] => Switching Protocols
    [200] => OK
    [201] => Created
    [202] => Accepted
    [203] => Non-Authoritative Information
    [204] => No Content
    [205] => Reset Content
    [206] => Partial Content
    [300] => Multiple Choices
    [301] => Moved Permanently
    [302] => Found
    [303] => See Other
    [304] => Not Modified
    [305] => Use Proxy
    [307] => Temporary Redirect
    [400] => Bad Request
    [401] => Unauthorized
    [402] => Payment Required
    [403] => Forbidden
    [404] => Not Found
    [405] => Method Not Allowed
    [406] => Not Acceptable
    [407] => Proxy Authentication Required
    [408] => Request Timeout
    [409] => Conflict
    [410] => Gone
    [411] => Length Required
    [412] => Precondition Failed
    [413] => Request Entity Too Large
    [414] => Request-URI Too Long
    [415] => Unsupported Media Type
    [416] => Requested Range Not Satisfiable
    [417] => Expectation Failed
    [500] => Internal Server Error
    [501] => Not Implemented
    [502] => Bad Gateway
    [503] => Service Unavailable
    [504] => Gateway Timeout
    [505] => HTTP Version Not Supported
    [509] => Bandwidth Limit Exceeded

Question: How to safely upgrade an Amazon EC2 instance from t1.micro to large?
Create a snapshot of your current image
Once snopshot done, then new to launch new instance.
Simply launch it as a large instance at that point.



Question: How to get the instance id from within an ec2 instance?
Login to EC2,and execute following command

wget -q -O - http://169.254.169.254/latest/meta-data/instance-id

Question: How to setup up FTP on Amazon Cloud Server?
https://stackoverflow.com/questions/7052875/setting-up-ftp-on-amazon-cloud-server



Question: What data is stored in Ephemeral Storage of Amazon EC2 instance?
When you mount your EBS volume at /myNewWebsite, then anything not in /myNewWebsite will be lost.


Question: Difference between EC2 and Elastic Beanstalk?
EC2
EC2 service that allows you to create a Ec2 instance in the AWS. You pay by the hour. you can create n instance and do the setting for each instance.

Elastic Beanstalk
Elastic Beanstalk is one layer of abstraction away from the EC2 layer.
In Beanstalk will setup an "environment" for you that can contain a number of EC2 instances, an optional database, as well as a few other AWS components such as a Elastic Load Balancer, Auto-Scaling Group, Security Group etc.



Question: What is difference between Lightsail and EC2?
EC2
EC2 service that allows you to create a Ec2 instance in the AWS. You pay by the hour. you can create n instance and do the setting for each instance.

Lightsail
Lightsail is designed to be the easiest way to launch and manage a virtual private server with AWS.
Lightsail plans include everything you need to start for your project – a virtual machine, SSD-based storage, data transfer, DNS management, and a static IP – for a low, predictable price.



Question: How to make clone of EC2?
You make an AMI of an existing instance, and then launch other instances using that AMI.



Question: .htaccess not working apache with my EC2 instance?

1. Login to SSH
2. Configure Apache mod_rewrite a2enmod rewrite
3. add the following code to /etc/apache2/sites-available/default

   AllowOverride All

4. Restart apache

   /etc/init.d/apache2 restart

Question: What happens when I reboot an EC2 instance?
Its similar as we reboot the system. None of data is deleted.
As per cost, no change in cost as they start charging when start instance and stop when terminate the instance.



Question: What is difference between Fixed Performance / Burstable Performance Instances?
AWS EC2 has 2 different type of instances: Fixed Performance Instances(for example M3, C3 etc) and Burstable Performance Instances (For example T2).

Fixed Performance Instances provides a consistent CPU performance whereas Burstable Performance Instances provide a baseline CPU performance under normal workload and when the workload increase on server then increase the CPU performance.



Question: What is CPU Credit?
CPU Credit regulates the amount of "CPU performance" can be increased under workload.
You can spend this CPU Credit to increase the CPU performance during the Burst period.
100% of CPU performance for 5 minutes, you will spend 5(i.e. 5*1.0) CPU Credit.


Question: What is CPU Credit Balance?
is simply the amount of CPU Credit available in your account at any moment.

AWS Tutorial Terminology page 8

Question: What is Amazon Resource Names (ARNs)?
Amazon Resource Names (ARNs) uniquely identify AWS resources across all of AWS resources, such as in IAM policies, Amazon Relational Database Service (Amazon RDS) tags.


Question: Give few sample of ARN Format?

arn:aws:elasticbeanstalk:us-east-1:123456789012:environment/My App/MyEnvironment


arn:aws:iam::123456789012:user/David


arn:aws:rds:eu-west-1:123456789012:db:mysql-db


arn:aws:s3:::my_corporate_bucket/exampleobject.png

Question: Explain syntax of ARN Format?

arn:partition:service:region:account-id:resource

arn:It is static
partition: Standard AWS regions the partition is aws.
service: The service namespace that identifies the AWS product like Amazon S3, IAM, or Amazon RDS.
region: Region of the service like west-1, west-2,
account: Account id from where its generated.
resource: The content of this part of the ARN varies by service. It often includes an indicator of the type of resource.



Question: What is Elastic ip address?
An Elastic IP address is a static IPv4 address designed for dynamic cloud computing.
An Elastic IP address is associated with your AWS account.


Question: What is public hosted zone?
A public hosted zone is a container that holds information about how you want to route traffic on the internet for a domain, such as example.com


Question: What is private hosted zone?
A private hosted zone is a container that holds information about how you want Amazon Route 53 to respond to DNS queries for a domain


Question: What is Amazon RDS Read Replicas?
Amazon RDS Read Replicas provide enhanced performance and durability for database which makes elastically scale out beyond the capacity constraints of a single DB instance for read-heavy database workloads.


You can create one or more replicas and serve high-volume application read traffic from multiple copies of your data.
Read replicas are available in Amazon RDS for MySQL, MariaDB, and PostgreSQL as well as Amazon Aurora.



Question: What is Amazon RDS Multi-AZ Deployments?
Amazon RDS Multi-AZ deployments provide enhanced availability and durability for Database (DB) Instances, making them a natural fit for production database workloads. When you provision a Multi-AZ DB Instance, Amazon RDS automatically creates a primary DB Instance and synchronously replicates the data to a standby instance in a different Availability Zone (AZ). Each AZ runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable.


Question: What AWS Key Management Service (KMS)?
KMS is a managed service where you can create and control the encryption keys used to encrypt your data, and uses FIPS 140-2 validated hardware security modules. KML is integrated with most other AWS services to help you protect the data you store with these services.


Question: What is difference between Amazon S3, EBS and EFS ?
Amazon S3: Amazon S3 stores data as objects. Each object in the storage contains a header with associated sequence of bytes from 0 byte to 5 TB.
EBS: EBS stores data as blocks of the same size and organizes as similar to a traditional file system, you can use it with EC2 instance.
EFS: EBS may be good for setting up a drive for virtual machines and and S3 is good for storage and EFS is good for both.

Amazon S3	Amazon EBS	Amazon EFS
Can be publicly accessible Web interface Object Storage Scalable Slower than EBS and EFS	Accessible only via the given EC2 Machine File System interface Block Storage Hardly scalable Faster than S3 and EFS	Accessible via several EC2 machines and AWS services Web and file system interface Object storage Scalable Faster than S3, slower than EBS
Good for storing backups	Is meant to be EC2 drive	Good for shareable applications and workloads