Top Interview Questions for AWS

1. What is AWS?

AWS stands for Amazon Web Services. It is a complete, secured, emerging cloud computing platform provided by Amazon.

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2. Compare between AWS and OpenStack.

3. What are the different layers of cloud computing?

• PaaS – Platform as a Service
• IaaS – Infrastructure as a Service
• SaaS – Software as a Service

4. How many layers are there in the cloud architecture? Name them.

There are 5 layers in cloud architecture which are listed below

• CC- Cluster Controller
• SC- Storage Controller
• CLC- Cloud Controller
• Walrus
• NC- Node Controller

5. What is the difference between scalability and flexibility?

The aptitude of any scheme to enhance the tasks on hand on its present hardware resources to grip inconsistency in command is known as scalability. The capability of a scheme to augment the tasks on hand on its present and supplementary hardware property is recognized as flexibility, hence enabling the industry to convene command devoid of putting in the infrastructure at all.  AWS has several configuration management solutions for AWS scalability, flexibility, availability, and management.

6. List the components required to build Amazon VPC.

Subnet, Internet Gateway, NAT Gateway, HW VPN Connection, Virtual Private Gateway, Customer Gateway, Router, Peering Connection, VPC Endpoint for S3, Egress-only Internet Gateway.

7. What is the importance of buffer in Amazon Web Services?

An Elastic Load Balancer ensures that the incoming traffic is distributed optimally across various AWS instances.  A buffer will synchronize different components and makes the arrangement additional elastic to a burst of load or traffic. The components are prone to work in an unstable way of receiving and processing the requests. The buffer creates the equilibrium linking various apparatus and crafts their effort at an identical rate to supply more rapid services.

8. How to secure data for carrying in the cloud?

One thing must be ensured that no one should seize the information in the cloud while data is moving from point one to another and also there should not be any leakage with the security key from several storerooms in the cloud. Segregation of information from additional companies’ information and then encrypting it by means of approved methods is one of the options.

9. What is auto-scaling?

Auto-scaling is one of the remarkable features of AWS where it permits you to arrange and robotically stipulate and spin up fresh examples without the requirement for your involvement. This can be achieved by setting brinks and metrics to watch. If those entrances are overcome, a fresh example of your selection will be configured, spun up, and copied into the weight planner collection.

 10. Which automation gears can help with spin-up services?

The API tools can be used for spin-up services and also for the written scripts. Those scripts could be coded in Perl, bash, or other languages of your preference. There is one more option that is patterned administration and stipulating tools such as a dummy or improved descendant. A tool called Scalar can also be used and finally, we can go with a controlled explanation like a Right scale.

11. Is it possible to scale an Amazon instance vertically? How?

Yes, it is possible. Just stop the server and then change its instance type and again start the server.

12. How the processes start, stop, and terminate works?

Starting and stopping of an instance: If an instance gets stopped or ended, the instance functions a usual power cut and then changes over to a clogged position. You can establish the case afterward since all the EBS volumes of Amazon remain attached. If an instance is in a stopping state, then you will not get charged for an additional instance.

Terminating the instance: If an instance gets terminated it tends to perform a typical blackout, so the EBS volumes which are attached will get removed except the volume’s delete on termination characteristic is set to zero. In such cases, the instance will get removed and cannot set it up afterward.

13. What is the relation between an instance and an Amazon Machine image?

Amazon Machine Image is basically a template consisting of software configuration parts. For example, an OS, applications, application server. If you start an instance, a duplicate of the AMI in a row as an unspoken attendant in the cloud.

14. What is DynamoDB?

DynamoDB is the service from AWS. It is used when you require a fast and flexible NoSQL database with a flexible data model and reliable performance.

15. Security elements used at network and server level in AWS?

A network ACL is network security for your Amazon VPC that acts as a firewall for controlling traffic in and out of one or more subnets.

Security Groups are security placed at the server level, which is the first level of defense.

16. How do you safeguard your EC2 instances running in VPC?

Security Groups can be used to protect your EC2 instances in a VPC. We can configure both inbound and outbound traffic in a Security Group, which enables secured access to your EC2 instances. Security Group automatically denies any unauthorized access to your EC2 instances.

17. In a VPC how many EC2 instances, you can use?

Initially, you are limited to launch 20 EC2 Instances at one time. The maximum VPC size is 65,536 instances.

18. Is it possible to establish a peering connection to a VPC in a different region?

IT is not possible. Peering Connection is available only between VPC in the same region

19. 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 an elastic fox or use the snapshot facility through an API call. Also, the performance can be improved by using Linux software raid and striping across four volumes.

20. 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.

21. What is the boot time for an instance store-backed instance?

The boot time for an Amazon Instance Store -Backed AMI is usually less than 5 minutes.

22. Is it possible to vertically scale on an Amazon Instance?  If yes, how?

Following are the steps to scale an Amazon Instance vertically –

• Spin up a larger Amazon instance than the existing one.
• Pause the existing instance to remove the root ebs volume from the server and discard it.
• Stop the live running instance and detach its root volume.
• Make a note of the unique device ID and attach that root volume to the new server.
• Start the instance again.

23. 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.

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

Hybrid Cloud Architecture

25. Is it possible to cast off S3 with EC2 instances? If yes, how?

It is possible to cast off S3 with EC2 instances using root approaches backed by native occurrence storage.

26. How will you configure an instance with the application and its dependencies, and make it ready to serve traffic?

You can achieve this with the use of lifecycle hooks. They are powerful as they let you pause the creation or termination of an instance so that you can sneak peek in and perform custom actions like configuring the instance, downloading the required files, and any other steps that are required to make the instance ready. Every auto-scaling group can have multiple lifecycle hooks.

27. What are some of the key best practices for security in Amazon EC2?

Create individual IAM (Identity and Access Management) users to control access to your AWS recourses. Creating separate IAM users provides separate credentials for every user, making it possible to assign different permissions to each user based on the access requirements.

• Secure the AWS Root account and its access keys.
• Harden EC2  instances by disabling unnecessary services and applications by installing only necessary software and tools on EC2 instances.
• Grant least privileges by opening up permissions that are required to perform a specific task and not more than that. Additional permissions can be granted as required.
• Define and review the security group rules on a regular basis.
• Have a well-defined strong password policy for all the users.
• Deploy anti-virus software on the AWS network to protect it from Trojans, Viruses, etc.

28. What should be the instance’s tenancy attribute for running it on single-tenant hardware?

The instance tenancy attributes must be set to a dedicated instance and other values might not be appropriate for this operation.

 29. What are the important features of a classic load balancer in EC2?

• The high availability feature ensures that the traffic is distributed among EC2 instances in single or multiple availability zones. This ensures a high scale of availability for incoming traffic.
• The classic load balancer can decide whether to route the traffic or not based on the results of the health check.
• You can implement secure load balancing within a network by creating security groups in a VPC.
• Classic load balancer supports sticky sessions which ensure that the traffic from a user is always routed to the same instance for a seamless experience.

30. What parameters will you take into consideration when choosing the availability zone?

Performance, pricing, latency, and response time are some of the factors to consider when selecting the availability zone.

31. Which instance will you use for deploying a 4-node Hadoop cluster in AWS?

We can use a c4. 8x large instance or i2.large for this, but using a c4.8x will require a better configuration on PC.

32. Will you use encryption for S3?

It is better to consider encryption for sensitive data on S3 as it is a proprietary technology.

33. How can you send the request to Amazon S3?

Using the REST API or the AWS SDK wrapper libraries which wrap the underlying Amazon S3 REST API.

34. How will you bind the user session with a specific instance in ELB (Elastic Load Balancer)?

This can be achieved by enabling Sticky Session.

35. What are the possible connection issues you encounter when connecting to an EC2 instance?

• Unprotected private key file
• Server refused key
• Connection timed out
• No supported authentication method available
• Host key not found, permission denied.
• User key not recognized by the server, permission denied.

36. Can you run multiple websites on an EC2 server using a single IP address?

More than one elastic IP is required to run multiple websites on EC2.

37. What happens when you reboot an EC2 instance?

Rebooting an instance is just similar to rebooting a PC. You do not return to the image’s original state, however, the contents of the hard disk are the same as before the reboot.

38. A content management system running on an EC2 instance is approaching 100% CPU utilization. How will you reduce the load on the EC2 instance

This can be done by attaching a load balancer to an autoscaling group to efficiently distribute load among all instances.

39. What happens when you launch instances in Amazon VPC?

Each instance has a default IP address when the instance is launched in Amazon VPC. This approach is considered ideal when you need to connect cloud resources with the data centers.

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40. Can you modify the private IP address of an EC2 instance while it is running in a VPC?

It is not possible to change the primary private IP addresses. However, secondary IP addresses can be assigned, unassigned, or moved between instances at any given point.

41. Which load balancer will you use to make routing decisions at the application layer or the transport layer that supports either VPC or EC2?

Classic Load Balancer