Top 25 AWS Interview Questions and Answers for 2025: Ace Your Cloud Computing Interview

Shilpa Prabhudesai

There is a major transformation in the way businesses and entities operate in today’s world. Due to the digitized nature of all operations, many institutions already deploy or are planning on deploying cloud computing for most of their activities, a trend that has created a huge demand for individuals with cloud computing skills.

Amazon Web Services (AWS) is the world’s most comprehensive and broadly adopted cloud platform. As more and more companies migrate to the cloud, AWS skills are required. Regardless of whether you are a cloud engineer, DevOps, solution architect , or developer, AWS interview questions come into play sooner or later, and it is therefore crucial to be prepared.

Here’s a list of the top 25 Amazon AWS interview questions and answers that will get you ready for the toughest of interviewers.

Introduction to AWS

AWS is a cloud computing service offered by Amazon and lets you build, test, deploy, and manage applications and services. All these are provided by AWS through data centers and the hardware managed by Amazon. AWS provides a combination of Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), and Software-as-a-Service (SaaS) offerings.

Professionals can use AWS to create virtual machines (VMs) armed with processing power, storage capacity, and analytics, along with networking and device management. AWS offers a pay-as-you-go model, which helps to avoid upfront costs and pay based on use. Its suite of tools is essential for companies worldwide. AWS is an integral part of modern-day business, offering efficacy, flexibility, and security.

Some of the features that distinguish AWS from other cloud platforms are:

AWS is the leading cloud service provider globally, offering a wide array of cloud computing services.
It was started in 2006 with three core services: storage, computing, and messaging.
AWS is used by major companies like Netflix, Airbnb, Spotify, and more.
AWS is known for its scalability, reliability, and extensive feature set.
AWS continuously enhances its network by providing a broad range of services, evolving based on market trends.

AWS Interview Questions and Answers

Here are the top 25 interview questions related to AWS and its various subtopics:

1. What is AWS?

Answer: AWS (Amazon Web Services) is a cloud computing platform that provides Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) offerings. It allows organizations to build, test, deploy, and manage applications without maintaining on-premise infrastructure.

Key Services offered by AWS are:

Compute: Amazon EC2, Lambda
Storage: S3, EBS, Glacier
Database: RDS, DynamoDB
Networking: VPC, Route 53, CloudFront

2. What are the key benefits of using AWS?

Answer: The key benefits of using AWS are:

Scalability: Auto Scaling and Elastic Load Balancing in AWS ensure applications handle variable traffic seamlessly.
Cost-effectiveness: AWS offers a Pay-as-you-go model with flexible pricing.
Reliability: It is a highly available and fault-tolerant architecture.
Security: AWS offers end-to-end encryption and compliance certifications, ensuring highly secure services.
Global Reach: AWS has 100+ Availability Zones across 30+ geographic regions, ensuring a large coverage.

3. What is an AWS Availability Zone (AZ)?

Answer: An Availability Zone is a physically separate data center within an AWS Region.
Each AZ has its own independent power, cooling, and networking. By physical separation of AZs, a single event like a fire or power outage can be prevented from affecting others.
AZs are connected to each other with high-bandwidth, low-latency networking to ensure high availability and fault tolerance. Applications are run across multiple AZs to ensure they remain operational even if one AZ experiences an outage.

Example: The region us-east-1 refers to the US East (N. Virginia) region. This region has six AZs, labeled as us-east-1a, us-east-1b, us-east-1c,us-east-1d, and us-east-1e.

4. What is Amazon S3?

Answer: Amazon Simple Storage Service (S3) is a cloud-based object storage service provided by AWS that offers secure, scalable, and durable storage for any type of data.

Two key components of Amazon S3 are:

Objects: These are the fundamental units of storage in S3. An object consists of a file (of any type) and optional metadata describing it.
Buckets: These are the containers for storing objects. Developers can create multiple buckets and control access permissions, logging, and the geographical region where the data resides for each bucket. Bucket names must be globally unique across all AWS accounts within a given region.

The key features of Amazon S3 are:

S3 can store unlimited objects up to 5TB each.
It can be accessed via HTTP(S) using the REST API.
S3 supports lifecycle management and versioning.

Typical Use Cases of Amazon S3 are:

Amazon S3 is used for storing data for cloud-native applications and mobile apps.
It is used for building data lakes for big data analytics.
S3 is also used for backup and disaster recovery solutions.
Archiving data for long-term retention and compliance can be done using S3.
It can be used for hosting static websites.

5. What is IAM in AWS?

Answer: IAM (Identity and Access Management) in AWS is a security service that controls user access and permissions for AWS resources by managing users, groups, roles, and their associated permissions.

IAM verifies who is requesting access (authentication) and determines what actions they are allowed to perform (authorization).

Key components of IAM include:

Users: Individual users who interact with AWS.
Groups: Collections of users that are assigned permissions so that multiple users have permissions at once.
Roles: An identity with temporary permissions given to users, applications, or services to access AWS resources.
Policies: JSON-based documents that define permissions and rules defining access levels and are attached to users, groups, or roles.

Policies enforce the principle of lease privilege, granting only the permissions necessary to perform a task.

Some of the usage examples of IAM are:

Creating a “DevTeam” group and assigning them read-only access to specific S3 buckets.
Granting an intern only the permission to start and stop EC2 instances, but not terminate them.
Allowing an application to assume a role to access another AWS service temporarily.

6. What is Amazon RDS?

Answer: Amazon Relational Database Service (RDS) is a managed web service provided by AWS that simplifies the setup, operation, and scaling of relational databases in the cloud.
RDS provides cost-efficient and resizable capacity while automating many of the time-consuming database administration tasks.
RDS supports popular relational database engines, including Amazon Aurora (MySQL and PostgreSQL compatible), PostgreSQL, MySQL, MariaDB, Oracle, SQL Server, and Db2.

Here are the key benefits of Amazon RDS:

It provides automated backups.
RDS supports multi-AZ deployments
It can read replicas for scaling.

7. What is Amazon VPC?

Answer: Amazon Virtual Private Cloud (VPC)is a service that allows users to create a logically isolated, virtual network within AWS. In Amazon VPC, users can launch resources like EC2 instances and databases. With VPC, users have complete control over a virtual networking environment, including IP address ranges, subnets, route tables, and network gateways, offering the benefits of a traditional data center with the scalability of the AWS cloud.

Core components of Amazon VPC include:

Subnets (public/private)
Internet Gateway (IGW)
NAT Gateway
Security Groups and Network ACLs

8. What are Security Groups in AWS?

Answer: AWS Security Groups are a virtual firewall that controls inbound and outbound traffic for AWS resources (like EC2 instances). They are the first layer of defense and use rules that specify which traffic (based on port ranges and protocols) is allowed to or from an instance.

AWS security groups are stateful, meaning that they maintain the state so that if an inbound request is allowed, the corresponding outbound return traffic is also automatically allowed.

Common examples of security groups in AWS are:

Inbound rule: A dedicated security group to manage and secure SSH access by allowing inbound traffic on TCP port 22, from a specific IP address or range.
Web servers: A security group that allows inbound traffic on TCP port 80 (HTTP) and port 443 (HTTPS) to web servers.
Database servers: A security group to restrict access to a database by allowing inbound connections only from users’ application servers, using their security group as the source.

9. What is AWS CloudFormation?

Answer: AWS CloudFormation is an Infrastructure as a Code (IaC) service from AWS that automates resource provisioning. AWS CloudFormation allows users to model and provision AWS resources in a declarative and automated way, treating infrastructure as code.

The key benefits of AWS CloudFormation are:

It offers consistent, repeatable setups.
AWS CloudFormation supports version-controlled infrastructure.
It offers easy rollback on errors.

10. Explain the difference between EC2 and Lambda.

Answer: The key differences between EC2 and Lambda are as follows:

EC2 (Elastic Compute Cloud) has the following key features:

Infrastructure as a Service (IaaS): EC2 provides virtual servers, known as instances, that offer full control over the operating system, software, and network configuration.
Server Management: Developers are responsible for managing the underlying server infrastructure, including operating system updates, security patches, and application deployments.
Always-On: EC2 instances are typically provisioned to run continuously, and the instance’s uptime is paid for, regardless of whether it is actively processing requests.
Use Cases: EC2 instances are suitable for applications requiring dedicated servers, long-running processes, custom operating system configurations, and applications with consistent, predictable workloads.

Lambda: Lambda service has the following key features:

Function as a Service (FaaS) / Serverless: Lambda is a serverless computing service in which code can be run without provisioning or managing servers. Developers simply upload code, and Lambda handles the underlying infrastructure.
Event-Driven: Lambda functions are event-driven and invoked in response to specific events, such as changes in data in an S3 bucket, messages in an SQS queue, or HTTP requests via API Gateway.
Ephemeral: Lambda functions are ephemeral, meaning they are spun up to execute code and then shut down when the execution is complete. Only the compute time consumed and the number of requests are billed.
Use Cases: Lambda service is ideal for event-driven architectures, microservices, data processing, real-time file processing, and applications with intermittent or unpredictable workloads.

11. What is the difference between a Region and an Availability Zone?

Answer: A Region is a large geographic area, and an Availability Zone (AZ) is a data center located within that region that is isolated and physically separate.

Regions are used for global reach and disaster recovery, while AZs provide high availability and fault tolerance within a region with independent power and networking. Workloads are spread across multiple AZs in a region to ensure that if one fails, the others can continue to operate.

The following table summarizes the differences between a Region and an AZ:

Aspect	Region	Availability Zones
Definition	Geographical area containing multiple data centers.	Individual data centers within a region.
Scope	It covers a large geographical area (e.g., U.S. East, Europe).	A single data center within a region (e.g., in U.S. East, there are multiple AZs).
Isolation	The region provides isolation between different parts of the world.	AZ provides isolation within a region, protecting against failures in other zones.
Purpose	Regions provide redundancy and compliance options.	AZs ensure fault isolation within a region.
Connectivity	A region is connected to other regions over the internet, which can be slower and more expensive.	AZ is connected to other AZs within the same region through high-speed, private networks.
Primary Use	Regions are primarily used for disaster recovery, data residency, and serving users in different geographic locations.	AZs are used for high availability, fault tolerance, and load balancing for applications.
Example	`us-east-1` (Virginia), `eu-west-1` (Ireland)	`us-east-1a`, `us-east-1b`

12. Explain S3 storage classes.

Answer: Amazon S3 (Simple Storage Service) offers various storage classes, each designed to optimize for different access patterns, cost requirements, and data durability needs. Using these storage classes, users can select the most suitable option for their specific use cases.

The main S3 Storage classes are as follows:

S3 Standard: This is a general-purpose storage for frequently accessed data. S3 standard class offers high durability, availability, and performance (low latency, high throughput).

S3 standard storage class is used in cloud applications, dynamic websites, content distribution, mobile and gaming applications, and big data analytics.

S3 Intelligent-Tiering: This class offers automatic cost optimization for data with unknown or changing access patterns. It automatically moves data between frequently accessed, infrequently accessed, and archive access tiers based on access patterns, reducing storage costs.

Data lakes, data analytics, user-generated content, and workloads with unpredictable access are the common use cases for this storage class.

S3 Standard-Infrequent Access (S3 Standard-IA): S3 Standard-IA is used for long-lived, infrequently accessed data requiring rapid access. It has a lower storage cost than S3 standard, but has high retrieval fees. It provides high availability and durability across multiple Availability Zones.

S3 Standard IA class is mainly used in backups, disaster recovery files, and long-term data storage.

S3 One Zone-Infrequent Access (S3 One Zone-IA): This class is used for infrequently accessed data stored in a single Availability Zone, and offers lower cost than S3 Standard-IA. Though it has a lower storage cost, the data is not resilient to the loss of an AZ. Retrieval fees are also applied.

This storage class is mostly suitable for secondary backup copies of on-premises data and easily re-creatable data.

Amazon S3 Glacier Instant Retrieval: This storage class stores archival data that needs immediate, millisecond access. It has low-cost archive storage with rapid retrieval at retrieval fees.

Amazon S3 Glacier Instant Retrieval is used in medical images, news media assets, and user-generated content that needs quick access.

Amazon S3 Glacier Flexible Retrieval (formerly S3 Glacier): This storage class is used for long-lived archive data that can tolerate retrieval times of minutes to hours. It has very low-cost archive storage with flexible retrieval options (expedited, standard, bulk).

Amazon S3 Glacier Flexible Retrieval storage class is used in long-term backups, disaster recovery, and data archiving for compliance.

Amazon S3 Glacier Deep Archive: This storage is the lowest-cost storage for long-term archive and digital preservation, with retrieval times of hours. It has extremely low-cost storage, suitable for data accessed once or twice a year, with retrieval fees.

It is used in highly regulated industries (healthcare, finance), for long-term data retention for compliance, and disaster recovery cases.

S3 Express One Zone: This storage class is used for most frequently accessed data and offers single-digit millisecond access. It has extremely low latency, high throughput, and data is stored in a single Availability Zone.

It is used in high-performance computing, machine learning training data, and interactive analytics.

13. What is the difference between IAM Roles and IAM Users?

Answer: The main difference between IAM users and IAM roles is that IAM Users are digital identities for specific people or applications with long-term credentials like passwords or access keys, while IAM Roles are for temporary access without credentials that can be assumed by users, applications, or services.

An IAM user has a persistent identity and credentials for ongoing access, whereas an IAM role is a set of permissions that a user or service assumes to gain temporary security credentials for a specific task.

An IAM user is uniquely tied to a single person or application, whereas an IAM role is assumed by multiple users, applications, or services as needed.

14. What is the difference between Security Groups and Network ACLs?

Answer: Security groups in AWS are stateful firewalls for individual instances that control traffic at the instance level with only “allow” rules. Network ACLs (NACLs) are stateless firewalls for subnets that use “allow” and “deny” rules and are evaluated in order. Security groups work on a per-instance basis, while NACLs work at the subnet level.

Security groups are associated with multiple instances. A subnet can only be associated with one NACL at a time, but one NACL can be associated with multiple subnets.

Some of the scenarios for using security groups and NACL are:

Security groups can be used to allow only specific ports to be open to the internet (e.g., port 80 for a web server) while preventing any other incoming connections to that instance.
Network ACLs can be used to block a specific IP address from accessing any resource in a particular subnet. An explicit “deny” rule can be created using NACL for that IP address.

15. Explain Amazon CloudFront.

Answer: Amazon CloudFront is AWS’s global Content Delivery Network (CDN) that delivers static, dynamic, and streaming content (webpages, images, videos) with low latency in a worldwide network of edge locations. When a user requests any type of content, CloudFront automatically routes the request to the nearest edge location, improving performance and reducing latency.

The key features of Amazon CloudFront are:

It is integrated with S3 and EC2.
CloudFront uses Edge Locations for caching.
It supports HTTPS and custom SSL certificates.
CloudFront operates on a pay-as-you-go pricing model and is cost-effective.
It can automatically handle high traffic spikes and offers security features like DDoS protection through services like AWS Shield and WAF.
CloudFront can automatically switch to a backup origin server if the primary one becomes unavailable, improving reliability.

Some of the usage examples of Amazon CloudFront are:

Website acceleration: CloudFront distributes static web content like HTML, CSS, JavaScript, and images to users worldwide.
Video streaming: It supports both live and on-demand streaming, delivering video content with low latency and high consistency.
Software and application delivery: CloudFront distributes large files and software updates, such as game patches and IoT firmware, at high transfer rates.
API delivery: APIs are delivered to users around the globe with low latency and high transfer speeds.

16. What is Elastic Load Balancing (ELB)?

Answer: Elastic Load Balancing (ELB) is a service that automatically distributes incoming application traffic across multiple EC2 instances, containers, and IP addresses to ensure high availability. Traffic is routed only to healthy targets and is scaled down to its own capacity to match the application’s load.

ELBs have the following main types:

Application Load Balancer (ALB) is used for HTTP/HTTPS traffic.
Network Load Balancer (NLB) is primarily for TCP/UDP traffic.
Gateway Load Balancer (GLB) is used in third-party virtual appliances.
Classic Load Balancer (CLB) is used in applications running on the EC2-Classic network.

ELBs have usage in the following:

Modern applications: Applications built with serverless components like AWS Lambda or containers use ELB to provide a native HTTP endpoint.
Scalable web applications: have an auto scaling group that is attached to an ELB, which automatically distributes the incoming web traffic across the group’s instances. As traffic fluctuates, the Auto Scaling group can add or remove instances, and the ELB automatically registers or deregisters them.
Hybrid cloud networking: ELB balances traffic across both AWS resources and on-premises resources, all through a single load balancer.
Appliance integration: A Gateway Load Balancer can route traffic to third-party network virtual appliances, such as firewalls, in a scalable way.

17. What is Auto Scaling in AWS?

Answer: AWS Auto Scaling automatically adjusts the number of resources, such as EC2 instances, based on demand, ensuring application performance and availability while optimizing costs.

Applications are continuously monitored and capacity is added or removed in real-time based on predefined scaling policies and plans that are configured for availability, cost, or a balance of both.

Here are the benefits of AWS auto scaling:

Auto-scaling maintains consistent and predictable performance during spikes.
It reduces costs during low-traffic periods.
Autoscaling integrates with CloudWatch for metric-based scaling.
It ensures applications are always available to users, even during unexpected traffic spikes.
Auto-scaling provides a unified interface to configure and manage scaling policies for multiple resources across different services, which is faster and easier than managing each resource individually.

18. What is Amazon CloudWatch?

Answer: Amazon CloudWatch is a monitoring and observability service for AWS cloud resources and applications in real time that collects and tracks metrics, logs, and events.
It provides system-wide visibility into the operational health of the system and helps with performance monitoring, resource optimization, and debugging by enabling users to visualize data and take automated actions.

The common use cases of Amazon CloudWatch are:

CloudWatch is used for setting alarms for EC2 instance health.
It monitors S3 bucket metrics.
It is used in visualizing system dashboards.
CloudWatch allows real-time tracking of metrics for various AWS resources like EC2 instances (CPU utilization, network I/O), RDS databases (connections, storage), and more.
It provides tools like CloudWatch ServiceLens, which integrates traces, metrics, and logs to offer an end-to-end view of application performance.
CloudWatch Logs and Events can be used to collect and analyze log data from various AWS services (e.g., CloudTrail for API activity).

19. What is AWS Elastic Beanstalk?

Answer: AWS Elastic Beanstalk is a managed service from AWS that simplifies application deployment and management in the AWS cloud. Using this service, developers can quickly deploy and run applications without needing to provision or manage the underlying infrastructure.

Elastic Beanstalk supports various programming languages and platforms, including Java, .NET, PHP, Node.js, Python, Ruby, Go, and Docker.

It handles provisioning, load balancing, and scaling. Elastic Beanstalk integrates with Git for CI/CD and is ideal for developers with minimal AWS expertise.

20. Explain AWS Lambda Triggers.

Answer: AWS Lambda Triggers are event sources that automatically invoke a Lambda function in response to specific activities or changes with AWS services or external applications. These are the mechanisms that initiate the execution of serverless code that enable event-driven architectures.

Some examples of Lambda triggers are:

S3 Trigger: Executed on object creation, deletion, or modification in an S3 bucket for image processing, data analysis, or log file processing.
DynamoDB Trigger: Executed when changes to items in a DynamoDB table (insertion, updates, or deletion) occur to perform real-time data processing or create audit logs.
API Gateway Trigger: This is triggered by HTTP requests to an API gateway to handle API logic and return responses.

21. What is Amazon Route 53?

Answer: Amazon Route 53 is AWS’s highly available and scalable cloud Domain Name System (DNS) web service for routing traffic to resources. It translates human-friendly domain names (for example, www.myapp.com) into the numeric IP addresses (for example, 192.0.1.0) that are used to connect to websites and applications.

Key functions of Amazon Route 53 include DNS routing, domain registration, and health checks, which allow for smart traffic management and increased application availability.

22. What is AWS CloudTrail?

Answer: AWS CloudTrail is a service that provides governance, compliance, and risk auditing by recording API calls made within an AWS account. It provides a record of actions taken by a user, role, or AWS service in an AWS account.
It logs API calls made through the management console, SDKs, command-line tools, and other AWS services, capturing details like the identity of the caller, the time, source IP, and parameters.

The key features of AWS CloudTrail are:

CloudTrail tracks user activity.
It stores logs in S3 for long-term analysis.
CloudTrail integrates with CloudWatch for alerts.

23. What are Spot Instances?

Answer: Spot Instances are a type of cloud computing resource that provides access to the cloud provider’s spare EC2 computing capacity offered at discounted rates (up to 90% off).

The spot instances are “interruptible,” meaning the provider can reclaim them with little notice when they need the capacity back or when the spot price exceeds the bid. They are ideal for flexible, fault-tolerant workloads such as big data processing, batch jobs, and certain web services.

24. What is AWS Elastic Container Service (ECS)?

Answer: AWS ECS is a fully managed container orchestration service that runs Docker containers on AWS and simplifies running, managing, and scaling containerized applications. It integrates with AWS Fargate, which allows you to run containers without managing servers.

25. What are AWS Pricing Models?

Answer: AWS provides several pricing options to suit various workloads, as given in the following table:

Model	Description	Use Case
On-Demand	Pay for usage without commitment.	Short-term workloads.
Reserved Instances	1-3 year commitment for lower cost.	Predictable workloads.
Spot Instances	Unused capacity at a discount.	Batch or flexible jobs.
Savings Plans	Flexible commitment to usage.	Long-term cost optimization.

Conclusion

Preparing for AWS interviews requires a blend of theoretical understanding and practical experience. The questions in this article cover key topics across compute, storage, networking, security, and architecture, the foundation of any AWS role.

By mastering these top 25 AWS interview questions, readers will be ready to tackle technical discussions confidently and stand out as a cloud professional.