AWS Interview Questions and Answers
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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 24×7 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. 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.
5. 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.
6. 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.
7. 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.
8. 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.
9. How many EC2 instances can be used in a VPC?
There is a limit of running up to a total of 20 on-demand instances across the instance family, you can purchase 20 reserved instances and request spot instances as per your dynamic spot limit region.
10. What should be the instance’s tenancy attribute for running it on single-tenant hardware?
The instance tenancy attribute must be set to a dedicated instance and other values might not be appropriate for this operation.
11. 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.
12. 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.
13. Will you use encryption for S3?
It is better to consider encryption for sensitive data on S3 as it is a proprietary technology.
14. How can you send a request to Amazon S3?
Using the REST API or the AWS SDK wrapper libraries which wrap the underlying Amazon S3 REST API.
15. How will you bind the user session with a specific instance in ELB (Elastic Load Balancer)?
This can be achieved by enabling the Sticky Session.
16. 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.
17. What happens when you reboot an EC2 instance?
Rebooting an instance is just similar to rebooting a PC. You do not return to image’s original state, however, the contents of the hard disk are the same as before the reboot.
18. A content management system running on an EC2 instance is approaching 100% CPU utilization. How will you reduce the load on EC2 instance?
This can be done by attaching a load balancer to an autoscaling group to efficiently distribute load among all instances.
19. 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 centres.
20. 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.
21. You are launching an instance under the free usage tier from AMI having a snapshot size of 50GB. How will you launch the instance under the free usage tier?
It is not possible to launch this instance under the free usage tier.
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