100 AWS Interview Questions and Answers: Comprehensive Guide for Beginners and Experienced Professionals

Basics and Cloud Services

1. What are the three basic types of cloud services? Provide examples of AWS products for each type.

   • Answer: The three basic types of cloud services are Computing, Storage, and Networking.
     • Computing: EC2, Elastic Beanstalk, Lambda, Auto-Scaling, Lightsail.
     • Storage: S3, Glacier, Elastic Block Storage (EBS), Elastic File System (EFS).
     • Networking: VPC, Amazon CloudFront, Route 53.

2. Explain the relationship between an AWS region and an Availability Zone.

   • Answer: AWS regions are separate geographical areas. Each region contains multiple isolated locations known as Availability Zones. Availability Zones within a region are connected through low-latency links.

3. What is auto-scaling?

   • Answer: Auto-scaling is an AWS feature that allows you to automatically adjust the number of EC2 instances based on the incoming application traffic and resource demand. It ensures the application maintains steady, predictable performance at the lowest possible cost.

Infrastructure Management

1. What is geo-targeting in CloudFront, and how does it help?

   • Answer: Geo-targeting in CloudFront allows businesses to create customized content based on the geographic location of users without changing the URL. It helps in delivering personalized experiences and relevant content to different audiences based on their location.

2. Describe the steps involved in a CloudFormation solution.

   • Answer:
     1. Create or use an existing CloudFormation template in JSON or YAML.
     2. Save the template in an S3 bucket.
     3. Use AWS CloudFormation to call the bucket and create a stack on your template.
     4. CloudFormation reads and provisions the services defined in the template in the specified order.

3. What is the process to upgrade or downgrade a system with near-zero downtime?

   • Answer:
     1. Open the EC2 console.
     2. Choose the operating system AMI.
     3. Launch a new instance with the desired instance type.
     4. Install updates and necessary applications.
     5. Test the new instance.
     6. Deploy the new instance and replace the older instance.
     7. Terminate the old instance.

Cost Management and Monitoring

1. List tools and techniques to ensure you are paying only for the resources you use in AWS.

   • Answer:
     1. Top Services Table: Shows the top five used services in the cost management console.
     2. Cost Explorer: Analyzes usage costs for the last 13 months and forecasts future costs.
     3. AWS Budgets: Helps plan and track utilization against budgets.
     4. Cost Allocation Tags: Identifies resources that incurred costs, helping to organize and manage expenses.

2. How can you log into the AWS environment other than using the console?

   • Answer: Options include:
     1. PuTTY: For SSH into instances.
     2. AWS CLI (Linux/Windows): Command line interface for managing AWS services.
     3. AWS SDK: For programmatically accessing AWS services.
     4. Eclipse: Using AWS Toolkit for IDE integration.

3. What are the services used to create a centralized logging solution in AWS?

   • Answer:
     1. Amazon CloudWatch Logs: Monitors and stores log files.
     2. Amazon S3: Centralized log storage.
     3. Amazon ElasticSearch service: To search, analyze, and visualize logs.
     4. Amazon Kinesis Firehose: Transports log data from S3 to Amazon ElasticSearch.

4. Describe the native AWS Security logging capabilities.

   • Answer:
     1. AWS CloudTrail: Provides a history of AWS API calls for every account, which is useful for security analysis, resource change tracking, and auditing.
     2. AWS Config: Offers detailed information about the configuration of AWS resources and records the configuration changes, which can be sent as notifications.

Security and Attack Prevention

1. What is a DDoS attack, and which AWS services can help minimize its impact?

   • Answer: A DDoS attack is a cyber-attack where multiple computers send a flood of requests to overwhelm and disrupt a service. AWS services such as AWS Shield, AWS WAF, Amazon Route 53, Amazon CloudFront, ELB, and VPC can help mitigate the impact of DDoS attacks.

2. What might be the reason you can't see a particular service in your region, and how can you fix it?

   • Answer: Not all AWS services are available in all regions. If a service is not visible in your region, it might not have been published there yet. To fix this, you can switch to a nearby AWS region where the service is available.

Real-Time Monitoring, Virtualization, and Global AWS Services

1. How do you set up a system to monitor website metrics in real-time in AWS?

   • Answer: Use Amazon CloudWatch to set up monitoring for various metrics such as state changes in EC2, Auto-scaling lifecycle events, scheduled events, and API calls. Set up custom dashboards and alarms to get real-time insights.

2. What are the types of virtualization in AWS, and what are their differences?

   • Answer:
     • Hardware Virtual Machine (HVM): Fully virtualized hardware with VMs booting from master boot records.
     • Paravirtualization (PV): Uses PV-GRUB for booting and requires specific kernels.
     • Paravirtualization on HVM: Combines PV and HVM benefits, allowing the OS to use storage and network I/O features of the host.

3. Can you name some AWS services that are not region-specific?

   • Answer:
     • IAM (Identity and Access Management)
     • Route 53 (DNS service)
     • Web Application Firewall (WAF)
     • CloudFront

Instance Management and Elastic Transcoding

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

   • Answer:
     • NAT Gateways are managed by AWS, are highly available within an availability zone, and support bursts of traffic up to 10 Gbps. They are more robust but more expensive.
     • NAT Instances are managed by the user, can be scaled up or down with instance sizes, and provide more control over configurations but require more maintenance.

2. What is Amazon CloudWatch?

   • Answer: Amazon CloudWatch is a monitoring and management service. It provides data and insights for AWS, hybrid, and on-premises applications and infrastructure resources. It tracks metrics, collects and monitors log files, sets alarms, and automatically reacts to changes in AWS resources.

3. What is an Elastic Transcoder?

   • Answer: Amazon Elastic Transcoder is a cloud-based media transcoding service. It converts media files from their original source format into various formats optimized for playback on different devices, like smartphones, tablets,and PCs. It is easy to use, cost-effective, and highly scalable.

Virtual Private Cloud (VPC) and EC2 Instances

1. With specified private IP addresses, can an Amazon EC2 instance be launched? If so, which AWS service makes it possible?

   • Answer: Yes, it is possible to launch an EC2 instance with specified private IP addresses using Amazon Virtual Private Cloud (VPC).

2. Define Amazon EC2 regions and availability zones.

   • Answer:
     • Regions are distinct geographic areas that contain multiple, isolated locations known as Availability Zones.
     • Availability Zones (AZs) are isolated locations within a region, designed to be isolated from failures in other AZs, and provide inexpensive, scalable, and redundant network connections to other AZs in the same region.

3. Explain Amazon EC2 root device volume.

   • Answer: The root device volume is the storage volume containing the image used to boot an EC2 instance. This can be either an Amazon EBS volume or an instance store volume, depending on the instance type.

4. Mention the different types of instances in Amazon EC2 and explain their features.

   • Answer:
   • General Purpose Instances: Suitable for a variety of workloads, offering balanced compute, memory, and network resources.
     • Examples: T3, T3a, M5.
   • Compute Optimized Instances: Designed for compute-intensive tasks like batch processing, high-performance web servers, and machine learning inference.
     • Examples: C5, C6g.
   • Memory Optimized Instances: Ideal for memory-intensive workloads such as in-memory databases and real-time big data analytics.
     • Examples: R5, X1.
   • Accelerated Computing Instances: Utilizes hardware accelerators for tasks like floating-point number calculations, data pattern matching, and graphics processing.
     • Examples: P3, G4.
   • Storage Optimized Instances: Designed for workloads requiring high sequential read and write access to very large data sets on local storage.
     • Examples: I3, D2.

Databases and Reserved Instances

1. Will your standby RDS be launched in the same availability zone as your primary?

   • Answer: No, standby instances in RDS are launched in different availability zones to ensure high availability and failover support.

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

   • Answer:
     • Spot Instances: Unused EC2 instances available at a discounted rate. They’re ideal for flexible, interruption-tolerant applications.
     • On-demand Instances: Pay-as-you-go instances with no long-term commitments or upfront payments; use them when needed without reservation.
     • Reserved Instances: Provide a significant discount in exchange for committing to a one- or three-year usage term. Suitable for predictable workloads.

3. How would you address a situation in which the relational database engine frequently collapses when traffic to your RDS instances increases, given that the RDS instance replica is not promoted as the master instance?

   • Answer: To handle increased traffic, you should vertically scale up to a larger RDS instance type and create read replicas for read-heavy workloads. Additionally, snapshots can be employed to backup data.

4. What do you understand by 'vCPU-based limits' in Amazon EC2, and how do they differ from 'instance count-based limits'?

   • Answer:
     • vCPU-based limits: These are limits on the number of virtual CPUs that can be used, allowing for better management and scaling based on the computational power needed across various instance types.
     • Instance count-based limits: These are older limits based on the number of instances used, regardless of their size or the computing power they provide.

AWS Data Transfer and Security

1. Define Snapshots in Amazon Lightsail.

   • Answer: Snapshots in Amazon Lightsail are point-in-time backups of instances, block storage volumes, and databases. They can be created manually or automatically and restored at any time to recover state and data.

2. On an EC2 instance, your application is active. If the CPU usage hits 80%, how do you reduce the load on it?

   • Answer: Configure an auto-scaling group to launch additional instances when CPU usage exceeds 80%. Use an Application Load Balancer to distribute the incoming traffic among the instances.

3. Multiple Linux Amazon EC2 instances running a web application are using Amazon EBS volumes for data storage. How can you ensure ACID compliance and increase resilience in case of a failure?

   • Answer:
     • Use AWS Auto Scaling and an Application Load Balancer across multiple Availability Zones for resilience.
     • Store data on Amazon EFS for shared file systems that provide ACID compliance and automatic scaling.

Storages and Backup

1. What service would you recommend if your company prefers to use its email address and domain for sending and receiving compliance emails, in an easy and budget-friendly manner?

   • Answer: Amazon Simple Email Service (Amazon SES) would be the best option for sending and receiving emails using your company’s domain in a cost-effective manner.

2. Describe Amazon SES.

   • Answer: Amazon Simple Email Service (SES) is a cloud-based email service provider designed to help digital marketers and application developers send marketing, notification, and transactional emails in a cost-effective and scalable way.

3. Describe PaaS.

   • Answer: Platform as a Service (PaaS) enables developers to build, deploy, and manage applications without worrying about the underlying hardware or software infrastructure. AWS Elastic Beanstalk is an example of PaaS.

4. How many S3 buckets can be created by default?

   • Answer: By default, you can create up to 100 S3 buckets per AWS account.

Elastic Compute Cloud (EC2) and Pricing Models

1. What is the maximum limit of elastic IP addresses that can be created per region?

   • Answer: By default, you can create up to 5 Elastic IP addresses per AWS account, per region.

2. What is Amazon EC2?

   • Answer: Amazon Elastic Compute Cloud (EC2) is a web service that provides resizable compute capacity in the cloud. It allows users to launch and manage virtual servers, known as instances, and offers scalable computing resources for applications.

3. What are some security best practices for Amazon EC2?

   • Answer:
     1. Use Identity and Access Management (IAM) to control access to AWS resources.
     2. Restrict access by only allowing trusted hosts or networks to access ports on an instance.
     3. Only allow needed permissions and disable password-based logins for instances launched from your AMIs.

4. Can S3 be used with EC2 instances, and if yes, how?

   • Answer: Yes, S3 can be used with EC2 instances. Developers can store AMIs in S3, move them between S3 and EC2, and utilize S3 buckets for data storage and retrieval for EC2 applications.

5. What is the difference between stopping and terminating an EC2 instance?

   • Answer: -- Stopping an EC2 instance: The instance performs a normal shutdown, moves to a "stopped" state, and the EBS volumes remain attached and data is preserved.
     • Terminating an EC2 instance: The instance stops and then deletes any attached EBS volumes. The instance cannot be restarted, and its data is lost.

6. What are the different types of EC2 instances based on their costs?

   • Answer:
     • On-demand Instances: Pay for compute capacity by the hour or second with no long-term commitments.
     • Spot Instances: Purchase unused compute capacity at a discounted rate.
     • Reserved Instances: Commit to a one- or three-year term for a significant discount over on-demand pricing.

7. How do you set up SSH agent forwarding so that you do not have to copy the key every time you log in?

   • Answer:
     • Open the PuTTY Configuration.
     • Navigate to the category SSH -> Auth.
     • Enable the SSH agent forwarding option.

Specialized Operating Systems and Backups

1. What are Solaris and AIX operating systems? Are they available with AWS?

   • Answer:
     • Solaris:An operating system that uses SPARC processor architecture, which is not supported by AWS.
     • AIX: An operating system that runs on the Power CPU and is not available on AWS as it doesn't support Intel architectures. Therefore, both are unavailable on AWS.

2. How do you configure CloudWatch to recover an EC2 instance?

   • Answer:
     1. Create an alarm in Amazon CloudWatch.
     2. In the Define Alarm action tab, choose "Recover this instance" as the action.
     3. Set the appropriate thresholds and conditions for the alarm.
     4. Once the alarm conditions are met, CloudWatch will recover the EC2 instance.

3. What are the common types of AMI designs?

   • Answer:
     • Fully Baked AMI: Contains all necessary software pre-installed.
     • Just Enough Operating System (JeOS) AMI: Contains a minimal operating system with critical applications.
     • Hybrid AMI: Mixes elements of fully baked and JeOS AMIs, containing critical software and allowing additional configuration.

Key Management and Storage Classes

1. What are key-pairs in AWS?

   • Answer: Key-pairsare password-protected login credentials for virtual machines. They consist of a public key stored by AWS and a private key stored by the user, allowing secure access to EC2 instances.

2. What is Amazon S3?

   • Answer: Amazon Simple Storage Service (S3) is an object storage service that offers scalable, durable, and secure storage for any amount of data. It provides various storage classes, lifecycle policies, and access controls.

Data Recovery and Elastic Block Storage (EBS)

1. How can you recover/login to an EC2 instance for which you have lost the key?

   • Answer:
     1. Verify that the EC2Config service is running.
     2. Detach the root volume of the instance.
     3. Attach the volume to a temporary instance.
     4. Modify the configuration file to replace the SSH key.
     5. Reattach the volume to the original instance and restart it.

2. What are some critical differences between AWS S3 and EBS?

   • Answer:
     • S3: Object storage, scalable, ideal for storing large-scale datasets, accessible from anywhere.
     • EBS: Block storage, attaches toEC2 instances, ideal for storing data that requires frequent access and consistent I/O performance, data persists even when an instance is stopped.

3. How do you allow a user to gain access to a specific bucket?

   • Answer:
     1. Create an IAM policy granting appropriate permissions to the bucket.
     2. Attach the policy to the IAM user or group requiring access.
     3. Alternatively, you can use bucket policies to define who can access the bucket and what actions they can perform.

4. How can you monitor S3 cross-region replication to ensure consistency without actually checking the bucket?

   • Answer: Use AWS CloudWatch metrics and configure CloudWatch alarms to monitor the replication status. These tools provide insights into replication progress and performance without requiring manual checks.

Data Transfer Tools and EFS Backups

1. What is Snowball?

   • Answer: AWS Snowball is a data transport solution that uses secure physical devices to transfer large amounts of data into and out of AWS. It allows users to efficiently move terabytes or petabytes of data to AWS, bypassing the internet.

2. What are the Storage Classes available in Amazon S3?

   • Answer:
     • Amazon S3 Standard: General-purpose storage for frequently accessed data.
     • Amazon S3 Standard-Infrequent Access (IA): For infrequently accessed data, with lower storage costs compared to Standard.
     • Amazon S3 One Zone-Infrequent Access (One Zone-IA): Lower-cost option for infrequently accessed data stored in a single availability zone.
     • Amazon S3 Glacier: Low-cost storage for data archiving with retrieval times ranging from minutes to hours.
     • Amazon S3 Glacier Deep Archive: Lowest-cost storage option for long-term data archiving with retrieval times of up to 12 hours.
     • Amazon S3 Intelligent-Tiering: Automatically moves data between two access tiers (frequent and infrequent) when access patterns change.
     • S3 Outposts: For data stored in on-premises AWS Outposts environments.

3. What Is Amazon Virtual Private Cloud (VPC) and Why Is It Used?

   • Answer: Amazon VPC allows users to create isolated cloud resources in a virtual network. It provides control over virtual networking environments, including selection of IP address ranges, subnets, route tables, and network gateways. It’s used to securely connect your datacenter toAWS resources, providing control over network settings and improving security through network segmentation and access controls.

4. Why would VPC not resolve the server through DNS, and how can you fix it?

   • Answer: This issue may occur due to DNS hostname resolution not being enabled for the VPC. You can fix it by:
     • Enabling DNS support for the VPC.
     • Enabling the DNS hostname setting for the VPC.

5. How do you connect multiple sites to a VPC?

   • Answer: Use AWS VPN CloudHub to provide secure communication between sites. This involves creating multiple VPN connections that use BGP routing to connect each site to the VPC and to each other.

6. Name and explain some security products and features available in VPC.

   • Answer:
     • Security Groups: Act as virtual firewalls for EC2 instances, controlling inbound and outbound traffic.
     • Network Access Control Lists (NACLs): Act as firewalls for subnets, controlling inbound and outbound traffic at the subnet level.
     • Flow Logs: Capture information about the IP traffic going to and from network interfaces in your VPC.

7. How do you monitor Amazon VPC?

   • Answer: You can monitor Amazon VPC using:
     • Amazon CloudWatch: For collecting and tracking metrics, collecting and monitoring log files.
     • VPC Flow Logs: To capture information about the IP traffic going to and from network interfaces in your VPC.

8. How many Subnets can you have per VPC?

   • Answer: You can have up to 200 subnets per Amazon Virtual Private Cloud (VPC).

Disaster Recovery and Autoscaling

1. When would you prefer Provisioned IOPS over standard RDS storage?

   • Answer: Provisioned IOPS should be used for
     • High-performance applications that require consistent and fast I/O throughput.
     • Workloads like OLTP (Online Transaction Processing) systems that need high I/O rates.

2. How do Amazon RDS, DynamoDB, and Redshift differ from each other?

   • Answer:
     • Amazon RDS: A relational database service for structured data, managing patching, backups, and updates.
     • DynamoDB: A NoSQL database service for unstructured data, providing fast and flexible data access.
     • Redshift: A data warehouseservice used for large-scale data analysis and querying.

3. What are the benefits of AWS’s disaster recovery?

   • Answer: AWS provides several benefits for disaster recovery:
     • Fast recovery times with rapid failover at scale.
     • Cost savings by eliminating the need for a second physical site.
     • Scalability and flexibility to adapt to different disaster recovery architectures.
     • Global data center infrastructure to support a wide range of recovery scenarios.

4. How can you add an existing instance to a new Auto Scaling group?

   • Answer:
     1. Open the EC2 console.
     2. Select your instance under Instances.
     3. Choose Actions > Instance Settings > Attach to Auto Scaling Group.
     4. Select a new Auto Scaling group and attach the group to the instance.
     5. Edit the instance settings if needed.

Migration and Resilience

1. What factors should you consider while migrating to Amazon Web Services?

   • Answer: Consider the following factors during AWS migration:
     • Operational Costs: Infrastructure costs, matching demand and supply, transparency.
     • Workforce Productivity: Efficiency improvements and personnel training.
     • Cost Avoidance: Reducing expenses byavoiding outdated technology.
     • Operational Resilience: Ability to recover quickly from failures.
     • Business Agility: Ability to scale resources quickly and efficiently.

2. What is RTO and RPO in AWS?

   • Answer:
     • RTO (Recovery Time Objective): The maximum acceptable amount of time that a system can be down after a failure or disaster.
     • RPO (Recovery Point Objective): The maximum acceptable amount of data loss measured in time that a business can tolerate.

3. If you need to transfer vast amounts of data, which is the best option among Snowball, Snowball Edge, and Snowmobile?

   • Answer:
     • Snowball: Best for transferring terabytes of data.
     • Snowball Edge: Adds additional computing capabilities along with data transfer.
     • Snowmobile: Best for transferring petabytes of data, suitable for large-scale data migrations.

4. What are T2 instances?

   • Answer: T2 instances are AWS's burstable performance instances that offer a baseline level of CPU performance with the ability to burst above the baseline. They are cost-effective and suitable for workloads that do not require sustained high CPU utilization, such as web servers, development environments, and small databases.

Identity and Access Management (IAM) and Connection Draining

1. What are the advantages of AWS IAM?

   • Answer:
     • Granular access control to AWS resources.
     • Enhanced security through defined user permissions.
     • Federated access capabilities.
     • Ability to create roles for applications and users, simplifying permission management.

2. Explain Connection Draining.

   • Answer: Connection Draining, now known as Deregistration Delay, enables you to serve existing requests on servers being removed or updated without disruption. It provides a grace period for in-flight requests to complete before deregistering the instances from the load balancer.

3. What is Power User Access in AWS?

   • Answer: Power User Access is an IAM policy that grants full access to AWS services and resources, except the ability to manage users and permissions. Power Users can create, read, update, and delete resources but cannot manage IAM users or roles.

CloudFormation and Elastic Block Storage (EBS)

1. How is AWS CloudFormation different from AWS Elastic Beanstalk?

   • Answer:
     • CloudFormation: Provides infrastructure as code, allowing you to define and provision AWS infrastructure using JSON or YAML templates. It supports a wide range of AWS resources and stacks.
     • Elastic Beanstalk: An application management service that automatically handles the deployment, scaling, monitoring, and patching of web applications and services. It focuses on application lifecycle management rather than infrastructure provisioning.

2. What are the elements of an AWS CloudFormation template?

   • Answer:
     • Template parameters: Let you customize aspects of your template.
     • Output values: Return values from the stack, such as an instance’s public IP.
     • Data tables: Used to map keys that CloudFormation templates can reference.
     • Resources: The AWS resources defined in the template.
     • File format version: Version of the AWS CloudFormation template format.

3. What happens if one of the resources in a CloudFormation stack cannot be created successfully?

   • Answer: CloudFormation automatically rolls back and terminates all the resources that were created in the stack template, maintaining the integrity of the infrastructure.

4. How can you automate EC2 backup using EBS?

   • Answer:
     1. Use AWS CLI or SDK to list the instances andconnect to AWS through the API.
     2. Identify and list the EBS volumes attached to the instance.
     3. Use the create-snapshot command to create a snapshot of each volume.
     4. Implement a retention policy to delete older snapshots based on retention period requirements.
     5. Automate the entire process using AWS Lambda and CloudWatch Events to run the backup process at regular intervals.

5. What is the difference between EBS and Instance Store?

   • Answer:
     • EBS (Elastic Block Store): Persistent block storage that remains available even after the instance is stopped or terminated. EBS volumes can be detached and reattached to different instances.
     • Instance Store: Temporary block storage that is physically attached to the host machine. Data in the instance store is lost when the instance is stopped or terminated, and the storage cannot be detached.

6. Can you take a backup of EFS like EBS, and if yes, how?

   • Answer: Yes, you can back up Amazon EFS (Elastic File System) using the EFS-to-EFS backup solution:
     • Sign in to the AWS Management Console.
     • Use the predefined "EFS-to-EFSBackup" solution available in the AWS marketplace or create a custom Lambda function that uses AWS Backup to automate snapshots.
     • Set up the region, template, and stack configuration.
     • The solution will automate the process of taking regular backups of EFS file systems and storing them in another EFS file system for recovery purposes.

7. How do you auto-delete old snapshots?

   • Answer:
     1. Use AWS Data Lifecycle Manager (DLM) to create lifecycle policies that automate the deletion of old EBS snapshots.
     2. Define rules for snapshot creation and retention periods.
     3. AWS DLM will automatically delete snapshots that exceed the specified retention period.

Elastic Load Balancing and Security

1. What are the different types of load balancers in AWS?

   • Answer:
     • Application Load Balancer (ALB): Best for HTTP and HTTPS traffic and provides advanced request routing features.
     • Network Load Balancer (NLB): Best for TCP, UDP, and TLS traffic, providing ultra-high performance and static IP addresses.
     • Classic Load Balancer (CLB): Supports both HTTP/HTTPS and TCP protocols and is the original Elastic Load Balancer.

2. What are the different uses of the various load balancers in AWS Elastic Load Balancing?

   • Answer:
     • Application Load Balancer (ALB): Ideal for web applications as it supports advanced routing, WebSocket, and HTTP/2 traffic.
     • Network Load Balancer (NLB): Suitable for applications that require extreme performance, low latency, or need to handle millions of requests per second.
     • Classic Load Balancer (CLB): Suitable for legacy applications or simple load balancing of HTTP/HTTPS and TCP traffic.

Identity and Access Management (IAM) and Route 53

1. What is Identity and Access Management (IAM) and how is it used?

   • Answer: IAM is a web service that helps you securely control access to AWS resources. It enables you to manage users, groups, policies, and roles for AWS services. IAM allows you to create fine-grained access policies to allocate different levels of access to various resources for different users or applications.

2. How can you use AWS WAF in monitoring your AWS applications?

   • Answer: AWS WAF (Web Application Firewall) allows you to monitor HTTP/HTTPS requests, create custom rulesto block common attack patterns, and define rules to allow or block traffic based on specific conditions. It can also provide insights into the traffic patterns and helps protect your web applications from SQL injection and cross-site scripting (XSS) attacks.

3. What are the different AWS IAM categories that you can control?

   • Answer:
     • IAM Users: Create and manage individual user accounts.
     • IAM Groups: Create groups to manage permissions collectively for multiple users.
     • IAM Roles: Create roles to grant permissions to AWS services and applications to interact with AWS resources.
     • IAM Policies: Create and manage policies to manage permissions and assign them to users, groups, and roles.

4. What are the policies that you can set for your users’ passwords?

   • Answer:
     • Set a minimum password length.
     • Require at least one uppercase letter, one lowercase letter, one number, and one special character.
     • Configure password expiration and disable re-use of old passwords.
     • Require users to reset their passwords periodically and possibly notify them when the password is about to expire.

5. What is the difference between an IAM role and an IAM user?

   • Answer: -IAM User: Represents a single person or service that interacts directly with AWS services using long-term security credentials like username and password or access keys.
     • IAM Role: Represents a set of permissions to make AWS service requests. It doesn’t have credentials associated with it and is used to delegate access to users, applications, or services needing temporary permissions.

6. What are managed policies in AWS IAM?

   • Answer: Managed policies are IAM policies that you can create and manage separately from attaching them to users, groups, or roles. AWS provides pre-built managed policies for common permissions, and you can also create custom managed policies according to your specific requirements.

7. Can you give an example of an IAM policy and a policy summary?

   • Answer:
     • Example IAM Policy:

        {
          "Version": "2012-10-17",
          "Statement": [
            {
              "Effect": "Allow",
              "Action": "s3:*",
              "Resource": "arn:aws:s3:::example-bucket/*"
            }
          ]
        }

• Policy Summary: This policy allows all actions (s3:*) on all objects within the example-bucket.

1. How does AWS IAM help your business?
   • Answer:
     • Manage IAM users and their access: Provides secure access to AWS resources for multiple users.
     • Manage access for federated users: Allows access to AWS resources for external identities (like enterprise users) without needing to create a new AWS identity.
     • Improve security: Implements fine-grained access control, ensuring that users have only the permissions they need.
     • Simplify permissions management: IAM roles and policies make it easier to manage permissions consistently across multiple users and services.

Domain Name System (DNS) and Configurations

1. What is Amazon Route 53?

   • Answer: Amazon Route 53 is a highly available and scalable Domain Name System (DNS) web service. It effectively routes end-user requests to infrastructure running in AWS, such as EC2 instances, Elastic Load Balancers, or S3 buckets. It also supports DNS failover, domain registration, and health checking.

2. What is CloudTrail and how do CloudTrail and Route 53 work together?

   • Answer: AWS CloudTrail captures API calls made in your AWS account and delivers log files to an S3 bucket. When integratedwith Route 53, it logs details of all requests made to the Route 53 API, including information about who made the request, when it was made, the source IP address, and other details.

3. What is the difference between Latency Based Routing and Geo DNS in Route 53?

   • Answer:
     • Latency Based Routing: Routes traffic to the AWS region that provides the lowest latency for the user’s location, ensuring optimal performance.
     • Geo DNS (Geolocation Routing): Routes traffic based on the geographic location of the end-users. This is useful for directing users to regional content specific to their location.

Monitoring, Data Aggregation, and Failover

1. What is the difference between a Domain and a Hosted Zone in Route 53?

   • Answer:
     • Domain: A general DNS concept referring to a collection of data describing a self-contained administrative and technical unit (e.g., example.com).
     • Hosted Zone: A DNS concept specific to Route 53, indicating a container holding information about how to route traffic for a specific domain (e.g., records for all subdomains of example.com).

2. How does Amazon Route 53 provide high availability and lowlatency?

   • Answer:
     • Globally Distributed DNS Servers: Route 53 is globally distributed, so DNS requests come from DNS servers close to the requester, reducing latency.
     • Health Checking and DNS Failover: It provides health-checking of resources and automatic failover to ensure high availability.
     • Anycast Routing: Uses anycast routing to respond to DNS queries from the optimal location for better performance.

Config Management and Database Services

1. How does AWS Config work with AWS CloudTrail?

   • Answer: AWS Config records the state of your AWS resources and tracks their changes over time. CloudTrail records API call information, including who made the call, when it was made, and what resource was affected. Together, they provide visibility into resource configurations and user activities, essential for auditing and compliance purposes.

2. Can AWS Config aggregate data across different AWS accounts?

   • Answer: Yes, AWS Config can be set up to deliver configuration updates from multiple AWS accounts to a single S3 bucket, enabling centralized monitoring and management of resource configurations across accounts.

3. How are reserved instances different from on-demand DB instances in RDS?

   • Answer:
     • Reserved Instances: Pre-purchased at a discounted rate for a one- or three-year term, offering significant savings over on-demand pricing.
     • On-Demand Instances: Pay-as-you-go pricing without long-term commitments, flexible and suitable for unpredictable workloads.

4. Which type of scaling would you recommend for RDS and why?

   • Answer:
     • Vertical Scaling: Recommended for scaling up individual RDS instances by increasing the instance size (CPU, memory) when more power is needed. It's appropriate for scenarios requiring higher performance from a single node.
     • Horizontal Scaling: Ideal for read-heavy workloads, it involves adding read replicas to distribute the read traffic and improve performance.

5. What is a maintenance window in Amazon RDS? Will your DB instance be available during maintenance events?

   • Answer: A maintenance window is a set period during which RDS performs system maintenance tasks, such as patching and upgrades. The DB instance remains available during these events, but there might be a brief disruption or performance impact during specific maintenance operations.

Consistency Models and Query Functionality

1. What are the consistency models in DynamoDB?

   • Answer:
     • Eventually Consistent Reads: Maximizes read throughput by returning responses from any highly available storage locations with the likelihood of eventual consistency.
     • Strongly Consistent Reads: Guarantees that the read returns the most recent write, but with reduced read throughput compared to eventually consistent reads.

2. What type of query functionality does DynamoDB support?

   • Answer:
     • GET/PUT Operations: Use a primary key for direct access.
     • Query Operations: Retrieves items based on primary key or secondary indexes (global secondary indexes and local secondary indexes) and supports sorting based on the sort key.
     • Scan Operations: Examines all items in a table or secondary index and returns a filtered result based on specified criteria.

Short Answer and Multiple-Choice AWS Interview Questions

1. Suppose you are a game designer and want to develop a game with single-digit millisecond latency. Which of the following database services would you use?

   • Answer: Amazon DynamoDB.

2. If you need to perform real-time monitoring of AWS services and get actionable insights, which services would you use?

   • Answer: Amazon CloudWatch.

3. As a web developer, you are developing an app targeted for the mobile platform. Which service letsyou add user sign-up, sign-in, and access control to your web and mobile apps quickly and easily?

   • Answer: Amazon Cognito.

Conclusion

These 100 questions and answers should comprehensively prepare you for various AWS interview scenarios. They cover AWS fundamentals, instance management, storage solutions, database services, and advanced concepts, providing a strong foundation for both beginners and experienced professionals. Good luck with your interview prep!

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