Top AWS Interview Questions and Answers for 2024

In today’s dynamic IT landscape, AWS Cloud Computing stands tall as a game-changer for career growth. Why? Because it’s not just about hosting data—it’s about transforming the way businesses operate. AWS provides a scalable, flexible, and secure platform, making it the go-to choice for organizations worldwide. Embracing AWS means diving into a realm of innovation, from machine learning to IoT, offering diverse opportunities. As businesses increasingly migrate to the cloud, professionals skilled in AWS become indispensable. It’s not just a trend; it’s a career necessity. AWS certifications validate your expertise, opening doors to exciting roles and ensuring you stay at the forefront of technology. In a world where digital agility is key, mastering AWS isn’t just an asset; it’s your ticket to a thriving IT career.

Important AWS Questions and answers

Here are some important AWS Questions and answers which may help you to clear concepts before attempting  AWS Certification Exam and AWS Job Interviews.

1. What is the difference between a Spot Instance, an On-demand Instance, and a Reserved Instance?

In the context of cloud computing, such as services provided by Amazon Web Services (AWS), the terms Spot Instance, On-Demand Instance, and Reserved Instance refer to different pricing models for virtual server instances. Here’s a brief explanation of each:

  1. On-Demand Instance:
    • On-Demand Instances are virtual servers that you can rent on an hourly or per-second basis without any upfront payment.
    • This pricing model is flexible, and you pay for the compute capacity you use, with no long-term commitments.
    • This is suitable for applications with variable workloads or for users who need instances for a short period.
  2. Reserved Instance:
    • Reserved Instances are purchased for a term of one or three years, offering a significant discount compared to On-Demand pricing.
    • They provide a capacity reservation, ensuring that the specified instance type is available when you need it.
    • Reserved Instances are recommended for applications with steady-state or predictable usage, as they require an upfront payment for the reserved term.
  3. Spot Instance:
    • Spot Instances allow you to bid for unused EC2 capacity at potentially lower costs than On-Demand Instances.
    • However, these instances can be terminated by AWS if the capacity is needed by someone willing to pay a higher price (your bid price is exceeded).
    • Spot Instances are suitable for fault-tolerant applications, batch processing, or workloads that can handle interruptions.

2. What is the relation between the Availability Zone and Region?

In cloud computing, specifically in the context of services like Amazon Web Services (AWS), a “Region” is a geographical area that consists of multiple “Availability Zones.”

Here’s the relationship between them:

  1. Region:
    • A Region is a physical location in the world where AWS has data centers.
    • AWS Regions are independent of each other and are designed to provide low-latency and high-availability to users in that geographic area.
    • Examples of AWS Regions include US East (N. Virginia), EU (Ireland), Asia Pacific (Mumbai), etc.
  2. Availability Zone (AZ):
    • An Availability Zone is essentially a data center within a Region.
    • Each Availability Zone is isolated but interconnected to provide redundancy and fault tolerance.
    • AWS customers can deploy their applications across multiple Availability Zones to enhance the availability and fault tolerance of their systems.

3. Explain the best services can be used to create a centralized logging solution in AWS?

AWS CloudTrail is a service provided by Amazon Web Services (AWS) that enables you to record and monitor activities and events that occur within your AWS infrastructure. It acts as a comprehensive audit trail, capturing details about API calls, console sign-ins, and other actions performed on your AWS account. Here are key aspects of AWS CloudTrail:

  1. Event Logging:
    • CloudTrail records events related to AWS resources and accounts, such as EC2 instance launches, S3 bucket creations, and changes to security groups.
    • Both management events (actions taken on resources) and data events (actions on data in resources) can be logged.
  2. Visibility and Accountability:
    • CloudTrail provides visibility into the historical changes to your AWS resources, aiding in security analysis, resource tracking, and compliance auditing.
    • It helps in maintaining accountability by associating actions with the identity of the entity (user or role) that performed them.
  3. Security and Compliance:
    • The service enhances security by monitoring for unauthorized or unexpected activity within your AWS environment.
    • It aids in meeting compliance requirements by providing a detailed record of API calls, facilitating audits and investigations.
  4. Log Storage:
    • CloudTrail logs are stored in an Amazon S3 bucket that you specify. This allows you to retain and access log files for an extended period.
    • You can configure CloudTrail to deliver log files to Amazon CloudWatch Logs for real-time monitoring and alerting.
  5. Integration with Other AWS Services:
    • CloudTrail can be integrated with other AWS services, such as CloudWatch, to set up alarms and respond to specific events in real-time.
    • It can also be integrated with AWS Identity and Access Management (IAM) for fine-grained control over who can access and manage CloudTrail.
  6. Global and Regional Events:
    • CloudTrail operates globally, recording events across all AWS regions, and you can choose to enable or disable CloudTrail on a per-region basis.

4.What is a DDoS attack, and what aws services can minimize them?

A DDoS (Distributed Denial of Service) attack is a malicious attempt to disrupt the regular functioning of a network, service, or website by overwhelming it with a flood of internet traffic. In a DDoS attack, multiple compromised computers (often part of a botnet) are used to flood the target system with traffic, causing a denial of service to legitimate users.

To minimize the impact of DDoS attacks, Amazon Web Services (AWS) provides several services that offer protection against such threats:

  1. Amazon Shield:
    • Amazon Shield Standard: Included at no extra cost with most AWS services, it provides automatic DDoS protection for all AWS customers.
    • Amazon Shield Advanced: This is a premium, subscription-based service offering enhanced DDoS protection. It includes 24/7 DDoS response, advanced threat intelligence, and DDoS cost protection.AWS Shield Advanced is available globally on all CloudFront, Global Accelerator, and Route 53 edge locations.
  2. Amazon CloudFront:
    • CloudFront is a content delivery network (CDN) that can help distribute the load of incoming traffic and absorb DDoS attacks by caching content at edge locations closer to end-users.
  3. AWS WAF (Web Application Firewall):
    • AWS WAF helps protect web applications from common web exploits and DDoS attacks by allowing you to control access to your content.
    • It enables you to set up rules to filter and monitor incoming web traffic and block malicious requests.
  4. Amazon Route 53:
    • Route 53, AWS’s domain name system (DNS) service, can be configured with health checks and failover policies to route traffic away from DDoS-affected regions or resources.
  5. Elastic Load Balancing (ELB):
    • ELB automatically distributes incoming application traffic across multiple targets, helping to distribute and mitigate the impact of DDoS attacks.
  6. Amazon VPC (Virtual Private Cloud):
    • Configuring security groups and network ACLs within VPC can help control incoming and outgoing traffic, providing an additional layer of protection.

By combining these AWS services, you can create a robust defense against DDoS attacks, ensuring the availability and reliability of your applications and services even under the threat of malicious traffic.

5.What are the differences between NAT Gateways and NAT Instances?

The differences between NAT Gateways and NAT Instances in AWS:

Feature NAT Gateways NAT Instances
Managed Service Yes No (requires manual configuration and management)
Availability Highly available across multiple Availability Zones Single instance (can be made highly available with Auto Scaling)
Elastic IP Association Automatically associated with the NAT Gateway Manually associated with the instance
Scalability Scales automatically based on traffic Requires manual adjustments, can use Auto Scaling group for scalability
Bandwidth Scales up to 45 Gbps (depending on the instance size) Limited by the instance type and can be a bottleneck
Maintenance AWS-managed service, no maintenance required Requires manual patching and maintenance
Security Groups Not associated with security groups (controlled by route tables) Associated with security groups
Network Performance Higher network performance Lower network performance (compared to NAT Gateways)
Cost Charged per hour and data processed Charged per hour (instance) and data processed

6.What do you understand by ‘changing’ in Amazon EC2?

The term “changing” in the context of Amazon EC2 typically refers to modifying the attributes or configurations of an existing EC2 instance. EC2 instances are virtual servers in the Amazon Web Services (AWS) cloud, and various aspects of their configuration can be adjusted to meet different requirements. Here are some common scenarios where “changing” an EC2 instance might be applicable:

  1. Instance Type:
    • Changing the instance type involves selecting a different combination of CPU, memory, storage, and networking capacity to better suit the performance requirements of your application.
  2. Elastic IP Address:
    • EC2 instances can be associated with Elastic IP addresses, and you can change this association if needed.
  3. Security Groups:
    • Security groups control inbound and outbound traffic to an EC2 instance. You can modify the rules of the security group to allow or restrict traffic.
  4. IAM Roles:
    • You can change the IAM (Identity and Access Management) role associated with an EC2 instance to adjust the permissions and access available to the instance.
  5. Network Interfaces:
    • Changes related to network interfaces include attaching or detaching network interfaces, changing their security groups, or modifying their IP addresses.
  6. Storage:
    • While you cannot directly change the size of the root volume of an instance, you can resize the EBS (Elastic Block Store) volumes associated with the instance.
  7. Placement Group:
    • If the instance is part of an EC2 placement group, you can change the placement group to control how instances are placed on the underlying hardware.
  8. Termination Protection:
    • You can enable or disable termination protection for an instance to prevent accidental termination.

It’s important to note that some changes may require stopping and restarting the EC2 instance, while others can be applied without interruption. Additionally, certain changes may have cost implications, so it’s advisable to review the AWS documentation and understand the impact of any modifications before making them.

7.What Are Some of the Security Best Practices for Amazon EC2?

Ensuring the security of Amazon EC2 instances is crucial for protecting your applications and data in the cloud. Here are some security best practices for Amazon EC2:

  1. Keep Software Updated:
    • Regularly apply security patches and updates to the operating system and software running on your EC2 instances to address known vulnerabilities.
  2. Use IAM Roles:
    • Assign IAM roles to EC2 instances to provide them with the least privilege necessary. Avoid using long-term access keys whenever possible.
  3. Enable Security Groups:
    • Utilize security groups to control inbound and outbound traffic to your EC2 instances. Only allow necessary ports and protocols.
  4. Implement Network ACLs:
    • Network ACLs act as an additional layer of security by controlling traffic at the subnet level. Use them to restrict traffic based on IP addresses.
  5. Encrypt EBS Volumes:
    • Enable encryption for your EBS (Elastic Block Store) volumes to protect data at rest. This is especially important for sensitive information.
  6. Monitor with CloudWatch:
    • Set up Amazon CloudWatch to monitor and log instance performance and system events. Establish alarms to be notified of unusual activities.
  7. Use Virtual Private Cloud (VPC):
    • Leverage VPC to isolate your EC2 instances logically. Use private and public subnets, and configure Network Access Control Lists (NACLs) and route tables for added security.
  8. Apply IAM Policies:
    • Define and enforce IAM policies to control access to AWS resources. Regularly review and update these policies based on the principle of least privilege.
  9. Enable Multi-Factor Authentication (MFA):
    • Enable MFA for accessing the AWS Management Console, especially for accounts with administrative privileges, to add an extra layer of security.
  10. Regularly Audit Permissions:
    • Regularly audit and review IAM user permissions, ensuring that users have only the necessary access required for their roles.
  11. Use Bastion Hosts or Jump Boxes:
    • When accessing instances in private subnets, use bastion hosts or jump boxes to control and monitor access.
  12. Implement Least Privilege Principle:
    • Adhere to the principle of least privilege for users, applications, and systems. Only grant the permissions necessary to perform specific tasks.
  13. Automate Security Checks:
    • Implement automated security checks using AWS Config Rules or third-party tools to continuously assess and enforce security configurations.
  14. Regularly Back Up Data:
    • Implement regular backups of your data, and test the restoration process to ensure business continuity in case of data loss or system failure.

By following these security best practices, you can enhance the security posture of your Amazon EC2 instances and contribute to a more robust and resilient cloud environment.

AWS Certification Training in Kolkata
AWS Certification Training in Kolkata

8.What do you understand about Key-Pairs in AWS?

In Amazon Web Services (AWS), a key pair is a set of security credentials that consists of a public key and a private key. This key pair is used for securely connecting to and authenticating with Amazon EC2 (Elastic Compute Cloud) instances. Here’s a breakdown of the key pair concept in AWS:

  1. Public Key:
    • The public key is the half of the key pair that you share or distribute. It is used by AWS to encrypt the information and verify the authenticity of the private key during the instance launch process.
  2. Private Key:
    • The private key is kept secret and securely stored on the client machine or the system from which you connect to your EC2 instance. It is used to decrypt information encrypted with the associated public key.
  3. EC2 Instance Authentication:
    • When launching an EC2 instance, you specify the name of the key pair to be associated with the instance. AWS stores the public key, and the private key is retained by the user. During the SSH (Secure Shell) login process for Linux instances or RDP (Remote Desktop Protocol) for Windows instances, the private key is used to authenticate the user.
  4. Key Pairs for Windows Instances:
    • For Windows instances, AWS uses a key pair for password generation rather than SSH key pairs. The private key is used to decrypt the initial administrator password provided by AWS.
  5. Key Pair Management:
    • You can create, import, and manage key pairs using the AWS Management Console, AWS CLI (Command Line Interface), or AWS SDKs (Software Development Kits).
  6. Security Considerations:
    • It’s crucial to keep the private key secure and not share it with unauthorized individuals. Compromising the private key could lead to unauthorized access to EC2 instances.
  7. Changing Key Pair for Existing Instances:
    • You cannot change the key pair associated with an existing EC2 instance. If you need to change the key pair, you would need to create an AMI (Amazon Machine Image) of the instance, launch a new instance with the desired key pair, and terminate the old instance.

Key pairs play a vital role in securing remote access to EC2 instances in AWS, and users must carefully manage and safeguard their associated private keys to maintain the integrity and security of their instances.

9.When Would You Prefer Provisioned IOPS over Standard RDS Storage?

Provisioned IOPS (Input/Output Operations Per Second) in Amazon RDS (Relational Database Service) is a storage option that allows you to specify the level of I/O performance that your database needs. Choosing Provisioned IOPS over Standard RDS storage depends on the performance requirements of your database workload. Here are scenarios where you might prefer Provisioned IOPS:

  1. High I/O Workloads:
    • If your database workload involves frequent and intense read/write operations, such as OLTP (Online Transaction Processing) systems, where low latency is crucial, Provisioned IOPS can provide consistent and predictable performance.
  2. Critical Production Databases:
    • For critical production databases where maintaining a consistent level of performance is essential, Provisioned IOPS is preferred. It ensures that the database can meet the I/O demands even during peak usage.
  3. Latency-Sensitive Applications:
    • Applications that are sensitive to storage latency, such as real-time analytics or applications with stringent SLAs (Service Level Agreements), may benefit from the low-latency characteristics of Provisioned IOPS.
  4. Databases with Fluctuating Workloads:
    • If your database experiences varying workloads and you need to ensure a consistent level of performance regardless of fluctuations, Provisioned IOPS allows you to allocate the necessary I/O capacity.
  5. IO1 Storage Type:
    • In Amazon RDS, Provisioned IOPS is associated with the “io1” storage type. If your application requires the features and performance benefits of the io1 storage type, then Provisioned IOPS is the appropriate choice.
  6. Databases with Specific SLAs:
    • When your application has specific SLAs that require a guaranteed level of I/O performance, Provisioned IOPS is the suitable option. It provides you with the ability to meet specific performance requirements.

It’s important to note that Provisioned IOPS typically comes with an additional cost compared to Standard RDS storage. Therefore, the decision to choose Provisioned IOPS should be based on a careful assessment of your application’s performance needs and budget considerations. If your database workload is not I/O-intensive and does not require consistently high performance, Standard RDS storage may be a cost-effective alternative.

10.What is RTO and RPO in AWS?

In the context of business continuity and disaster recovery planning, two critical metrics are often used to define the objectives of a recovery strategy: RTO and RPO.

  1. RTO (Recovery Time Objective):
    • Definition: RTO represents the maximum acceptable downtime for a system or service after a disruption. It indicates the duration within which the system or service must be restored and brought back to normal operation to avoid significant negative consequences.
    • Example: If an application has an RTO of 4 hours, it means that in the event of a disruption, the goal is to have the application fully operational again within 4 hours.
  2. RPO (Recovery Point Objective):
    • Definition: RPO defines the acceptable data loss in the event of a disruption. It represents the maximum amount of data that can be lost without causing significant harm to the business. RPO is essentially a measure of the age of the backup data that can be tolerated.
    • Example: If a database has an RPO of 1 hour, it means that, in the event of a failure, the goal is to recover the data with a maximum loss of 1 hour’s worth of transactions.

In the context of AWS:

  • AWS Services for Achieving RTO and RPO:
    • AWS provides various services and features that help organizations meet their RTO and RPO objectives. These include automated backup solutions, multi-Availability Zone deployments, and disaster recovery services like AWS Backup, Amazon RDS automated backups, and AWS Elastic Beanstalk environment updates.
  • Multi-Availability Zone Deployments:
    • Deploying resources across multiple Availability Zones (AZs) helps improve both RTO and RPO by providing redundancy and ensuring that if one AZ is affected, resources can quickly failover to another.
  • Backups and Snapshots:
    • Regularly creating and storing backups or snapshots of your data is crucial for meeting RPO objectives. AWS services like Amazon RDS, Amazon EBS, and Amazon EC2 offer automated backup features.

Understanding and defining RTO and RPO are essential steps in designing a robust and effective disaster recovery plan in the AWS cloud. These metrics help organizations set clear goals for recovery and ensure that they can resume normal operations with minimal disruption and data loss in the event of unforeseen incidents.

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