Showing posts with label spot. Show all posts
Showing posts with label spot. Show all posts

November 22, 2021

Top 20 AWS Solution Architect Interview Questions & Answers


Ques: 1). I have a few private servers, and I also use the public cloud to share some workloads. What kind of structure is this?


The hybrid cloud is created when both private and public cloud services are combined. When private and public clouds are virtually housed on the same network, it is easy to comprehend a hybrid architecture.


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Ques: 2). What's the difference between stopping and terminating an instance?


Stopping an Instance: When you stop an instance, it goes through a standard shutdown process. Its Amazon EBS volume, on the other hand, remains attached, and you may restart the instance whenever you want. The advantage of stopping an instance is that you will not be charged for that instance once it has been terminated.

Terminating an Instance: When an instance is terminated, it goes through a normal shutdown and any Amazon EBS volumes attached to the instance are destroyed at the same time. You cannot restart an instance once it has been terminated.

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Ques: 3). What distinguishes a Spot Instance from a Reserved or On-Demand Instance?


Pricing models include Spot instances, Reserved instances, and On-demand instances. Users can buy compute power without making an upfront investment using a spot instance, however they must pay hourly, which is lower than the on-demand instance fee in each area.

Spot instances are analogous to bidding, and the Spot Price is the bidding price for these instances. The price may fluctuate due to availability and demand, but you will never pay more than the maximum amount mentioned. In the event that spot prices rise above the maximum price, the EC2 instances will automatically shut down. The opposite is not true: if spot prices fall, EC2 Instances are not instantly launched. It's possible to do it manually.

There is no obligation on the part of the user for Spot and On-demand instances. In the case of Reserved Instances, however, one must keep to the time period that was previously selected.

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Ques: 4). In AWS, which instance type should you use to deploy a 4-node Hadoop cluster?


Each Hadoop cluster is built on a master-slave model, in which the master system processes the data and the slave machine acts as a data node. Because all of the processing is done on the master system, it requires a high-capacity CPU and RAM, and because all of the storage is done on the slave machine, a large hard disc is required.

You have complete control over the machine's setup based on the workload. If you don't want to configure the computer manually, you can immediately launch an Amazon EMR instance that will do it for you. You dump the data to be processed in S3, EMR picks the data from there, processes it, and dumps it back to the S3.

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Ques: 5). Is a single Elastic IP address sufficient for all running instances?


Each instance has its own public and private addresses. When an instance is stopped or terminated, it returns a private address that is unique to that instance. Similarly, until the instance is halted or terminated, a public address is connected only with it. However, an EIP (Elastic IP address) can be assigned to an instance that will remain active until the user detaches it manually. In the event that you are hosting multiple websites on your EC2 server, you will require different EIP numbers.

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Ques: 6). Is it possible to use an S3 bucket with EC2 Instances as well?


Yes, it's possible to utilise it with root devices that are backed up by local instances storage. Amazon S3 gives developers access to the same dependable and expensive data storage infrastructure that Amazon uses to power its global websites.

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Ques: 7). Explain how to use Amazon Instance to vertically scale.


The following are the steps to vertically scale on Amazon:

  1. Upgrade from the current instance to a new larger instance.
  2. Pause the previous instance and discard it by detaching the root web volumes from the servers.
  3. Now stop the live instance and also detach its root volume.
  4. Attach the root volume to the new server after you note the unique device ID.
  5. And finally, restart it.

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Ques: 8). What does a buffer do in Amazon web services?


The buffer is used to make the system more robust for managing traffic or load by synchronising multiple components. The components, in general, receive and process requests in an uneven manner. When the buffer is used, however, the components are balanced and operate at the same speed, ensuring that proper service is provided.

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Ques: 9). What kind of performance can Elastic Block Storage provide? How do you back it up and improve the results?


The performance of elastic block storage fluctuates, and it might go above and below the SLA performance threshold. SLA gives an average disc I/O rate, which can irritate performance experts who want a server's disc throughput to be consistent and reliable. This is not the case with virtual AWS instances. A graphical user interface, such as elasticfox, can be used to backup EBS volumes, or an API call can be used to leverage the snapshot feature. Using Linux software raid and striping over four drives can further increase performance.


Ques: 10). Distinguish between an on-demand and a spot instance.


Spot Instances are unused Amazon EC2 instances that can be bid on. The spot instance will be launched once the bid exceeds the current spot price (which changes in real-time based on demand and supply). If the spot price exceeds the bid price, the instance can be cancelled at any time and with only 2 minutes' notice. The best technique to determine the best bid price for a spot instance is to consult the AWS console's price history for the previous 90 days. Spot instances have the benefit of being cost-effective, but the disadvantage is that they can be cancelled at any time. 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 available anytime you need them, and you must pay on an hourly basis for the time you utilise them. These instances can be released as soon as they are no longer needed, and there is no commitment required up front. Unlike spot instances, AWS guarantees the availability of these instances.

The recommended practise is to start a few on-demand instances that can provide a minimal level of assured compute resources for the application and then add on a few spot instances as needed.


Ques: 11). What is Amazon EMR and how does it work?


Amazon EMR is a surviving cluster stage that is useful in data structures since it demonstrates how things work before they are notified. On Amazon Web Services, Apache Spark and Apache Hadoop are useful for analysing massive amounts of data. Data for analytics purposes and marketing intelligence workloads can be prepared using Apache Hive. It also makes use of other open-source ideas that are applicable.


Ques: 12). Is it possible to scale an Amazon Instance vertically? If so, how do you go about doing it?


The steps to vertically scale an Amazon Instance are as follows –

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


Ques: 13). How will you prepare an instance to serve traffic by configuring it with the application and its dependencies?


The use of lifecycle hooks can help you do this. They are useful because they allow you to halt the construction or termination of an instance so that you can sneak a peek inside and do specific activities such as configuring the instance, downloading relevant files, and performing any other steps necessary to get the instance ready. There can be many lifecycle hooks in each auto scaling group.


Ques: 14).  How can EC2 instances running in a VPC be protected?


AWS Security groups connected with EC2 instances can help you protect EC2 instances running in a VPC by enforcing protocol and port access security. You can secure access to the EC2 instance by configuring both INBOUND and OUTBOUND traffic. AWS security groups are similar to firewalls in that they contain a collection of rules that filter traffic entering and exiting an EC2 instance and prevent unauthorised access to those instances.


Ques: 15). What are some of the most important security best practises in Amazon EC2?


To limit access to your AWS resources, create unique IAM (Identity and Access Management) users. Creating a unique IAM user gives each user their own set of credentials, allowing them to be given varying permissions based on their access needs.

  • 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.


Ques: 16). What are the key characteristics of a traditional load balancer in EC2?


The high availability functionality distributes traffic among EC2 instances in a single or several availability zones.

This assures a high level of incoming traffic availability.

Based on the findings of the health check, a traditional load balancer can decide whether or not to route traffic.

By defining security groups in a VPC, you may achieve safe load balancing within a network.

Sticky sessions are supported by traditional load balancers, which ensure that a user's traffic is always routed to the same instance for a consistent experience.


Ques: 17).  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.


Ques: 18). What's the difference between stopping and terminating an EC2 instance?


When you end an EC2 instance, it goes into a standard shutdown mode and is moved to the stop state. When an EC2 instance is terminated, it is put into a suspended state, and any EBS volumes attached to it are erased and can't be restored.


Ques: 19). How can you use EBS to automate EC2 backups?


Creating snapshots of EBS volumes can be used to back up AWS EC2 instances. Amazon S3 is utilised to store the snapshots. Snapshots can capture all of the data in EBS volumes and produce precise replicas of it. The snapshots can then be cloned and relocated to another AWS region, ensuring that sensitive data is kept safe and secure.

Stopping the instance or detaching the EBS volume that will be backed up is suggested before executing AWS EC2 backup. Any failures or problems will not effect newly produced snapshots as a result of this.

The following steps must be followed to back up an AWS EC2 instance:

  1. Sign in to the AWS account, and launch the AWS console.
  2. Launch the EC2 Management Console from the Services option.
  3. From the list of running instances, select the instance that has to be backed up.
  4. Find the Amazon EBS volumes that are attached locally to that particular instance.
  5. List the snapshots of each of the volumes, and specify a retention period for the snapshots. A snapshot has to be created of each volume too.
  6. Remember to remove snapshots that are older than the retention period.


Ques: 20). What is a denial-of-service (DoS) attack, and how do you respond to one?


When a malicious attempt is made to affect the availability of a certain system, such as an application or a website, a Denial of Service (DoS) attack occurs. When an attacker uses many sources to generate a DDoS attack, it is known as a Distributed Denial of Service attack. DDoS assaults are usually classified according to whatever layer of the Open Systems Interconnection (OSI) model they target. The Network, Transport, Presentation, and Application levels, which correspond to layers 3,4,6, and 7, are the most typical targets for DDoS attacks.