Preparing for an AWS interview in 2026? Whether you are applying for a cloud engineer, DevOps engineer, or solutions architect role, this guide covers the top 50 AWS interview questions with in-depth, practical answers to help you stand out.
AWS remains the world’s leading cloud platform, 50 AWS Interview Questions and Answers (2026) and demand for certified AWS professionals is at an all-time high in 2026. These questions cover everything from core services like EC2, S3, and IAM to advanced topics like Lambda, VPC, and RDS.
Also read: Top 50 DevOps Interview Questions and Answers (2026) | Top 50 Docker Interview Questions (2026) | Top 50 Kubernetes Interview Questions (2026)
AWS Basics — Interview Questions 1 to 10
1. What is AWS and what are its key benefits?
AWS (Amazon Web Services) is a comprehensive cloud computing platform provided by Amazon. It offers over 200 fully featured services including computing power, storage, databases, networking, machine learning, and security — all delivered over the internet on a pay-as-you-go model.
Key benefits: scalability, flexibility, cost savings, global reach, high availability, and a broad ecosystem of managed services that reduce operational overhead.
2. What is the difference between EC2 and Lambda?
EC2 (Elastic Compute Cloud) provides virtual machines where you manage the operating system, runtime, and scaling. Lambda is a serverless compute service where you only provide the code — AWS manages the infrastructure, scales automatically, and you pay only per execution.
Use EC2 for long-running applications or when you need full control. Use Lambda for event-driven, short-duration tasks like API responses, file processing, or scheduled jobs.
3. What is an S3 bucket and what can it store?
Amazon S3 (Simple Storage Service) is an object storage service. An S3 bucket is a container that stores objects — files of any type including images, videos, backups, logs, static website assets, and application data. Each object is identified by a unique key within the bucket.
S3 offers 99.999999999% (11 nines) durability, making it one of the most reliable storage solutions available.
4. What is IAM in AWS?
IAM (Identity and Access Management) is the AWS service that controls who can access which AWS resources and what actions they can perform. It lets you create users, groups, and roles, and attach policies that define permissions.
Best practice is to follow the principle of least privilege — grant only the permissions needed for a specific task, nothing more.
5. What is a VPC?
A VPC (Virtual Private Cloud) is a logically isolated section of the AWS cloud where you can launch resources in a virtual network you define. You control the IP address range, subnets, route tables, and network gateways.
VPCs allow you to separate public-facing resources (web servers) from private ones (databases) and control traffic flow between them using security groups and network ACLs.
6. What is the difference between a public subnet and a private subnet?
A public subnet has a route to an Internet Gateway, meaning resources in it can communicate directly with the internet. A private subnet has no direct route to the internet — resources in it can only communicate within the VPC or through a NAT Gateway for outbound traffic.
Web servers typically sit in public subnets. Databases and application servers typically sit in private subnets for security.
7. What is Auto Scaling in AWS?
Auto Scaling automatically adjusts the number of EC2 instances in your application based on demand. When traffic increases, it adds instances. When traffic drops, it removes them. This ensures your application is always available while keeping costs optimised.
You define minimum, maximum, and desired instance counts, along with scaling policies based on metrics like CPU utilisation or request count.
8. What is the difference between vertical scaling and horizontal scaling?
Vertical scaling means increasing the size of a single instance — adding more CPU, RAM, or storage to handle more load. Horizontal scaling means adding more instances to distribute the load across multiple machines.
AWS is designed for horizontal scaling, which is more resilient and cost-effective at scale.
9. What is CloudWatch?
Amazon CloudWatch is AWS’s monitoring and observability service. It collects metrics, logs, and events from AWS services and your own applications. You can set alarms to trigger actions (like Auto Scaling) when a metric crosses a threshold, and use dashboards to visualise your infrastructure health in real time.
10. What is the AWS Shared Responsibility Model?
The Shared Responsibility Model defines what AWS is responsible for and what the customer is responsible for. AWS manages the security of the cloud (hardware, software, networking, facilities). The customer manages security in the cloud (data, access management, operating systems, application configuration).
AWS Storage and Databases — Questions 11 to 20
11. What is the difference between S3, EBS, and EFS?
S3 is object storage — best for unstructured data, backups, and static assets accessible over HTTP. EBS (Elastic Block Store) is block storage attached to a single EC2 instance — best for databases and operating system volumes. EFS (Elastic File System) is a managed file system that can be mounted by multiple EC2 instances simultaneously — best for shared storage across servers.
12. What are S3 storage classes?
S3 offers multiple storage classes for different use cases: S3 Standard for frequently accessed data, S3 Intelligent-Tiering for data with changing access patterns, S3 Standard-IA and S3 One Zone-IA for infrequent access, S3 Glacier Instant Retrieval and S3 Glacier Flexible Retrieval for archival data, and S3 Glacier Deep Archive for long-term, rarely accessed archives at the lowest cost.
13. What is Amazon RDS?
Amazon RDS (Relational Database Service) is a managed service for relational databases. It supports MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, and Amazon Aurora. RDS handles backups, patching, replication, and failover automatically, so you focus on your data rather than database administration.
14. What is the difference between RDS and DynamoDB?
RDS is a managed relational (SQL) database best for structured data with complex queries and transactions. DynamoDB is a fully managed NoSQL database best for high-speed, high-volume workloads with simple key-value or document access patterns. DynamoDB scales to millions of requests per second with single-digit millisecond latency.
15. What is Amazon Aurora?
Aurora is AWS’s cloud-native relational database engine, compatible with MySQL and PostgreSQL. It delivers up to 5x the throughput of standard MySQL and 3x that of standard PostgreSQL, with automatic storage scaling up to 128TB, multi-region replication, and serverless options.
16. What is ElastiCache?
ElastiCache is a managed in-memory caching service supporting Redis and Memcached. It is used to speed up applications by caching frequently accessed data — reducing the load on databases and cutting response times from milliseconds to microseconds.
17. What is S3 versioning?
S3 versioning keeps multiple versions of an object in the same bucket. When enabled, every upload creates a new version rather than overwriting the existing one. This protects against accidental deletion or overwrite, and allows you to restore previous versions of any object.
18. What is a snapshot in AWS?
A snapshot is a point-in-time backup of an EBS volume stored in S3. Snapshots are incremental — only the blocks that have changed since the last snapshot are saved, making them efficient. They can be used to create new EBS volumes or move data across regions.
19. What is AWS Glacier used for?
AWS Glacier (now part of the S3 Glacier storage classes) is designed for long-term archival storage of data that is rarely accessed. It offers very low storage costs in exchange for retrieval times ranging from minutes to hours, making it ideal for compliance archives, backups, and historical data.
20. What is Amazon Redshift?
Amazon Redshift is a fully managed, petabyte-scale data warehouse service optimised for analytical queries across large datasets. It uses columnar storage and parallel query execution, making it fast for business intelligence and reporting workloads.
AWS Networking — Questions 21 to 30
21. What is a Security Group in AWS?
A Security Group acts as a virtual firewall for your EC2 instances, controlling inbound and outbound traffic at the instance level. Rules specify allowed protocols, ports, and source/destination IP ranges. Security Groups are stateful — if you allow inbound traffic on a port, the response traffic is automatically allowed outbound.
22. What is the difference between a Security Group and a Network ACL?
Security Groups operate at the instance level and are stateful. Network ACLs (Access Control Lists) operate at the subnet level and are stateless — meaning you must explicitly allow both inbound and outbound traffic. Network ACLs are evaluated in order and support both allow and deny rules, while Security Groups only support allow rules.
23. What is an Elastic IP?
An Elastic IP is a static, public IPv4 address you allocate to your AWS account. Unlike the dynamic public IP assigned to an EC2 instance by default (which changes on restart), an Elastic IP persists until you release it and can be reassigned to different instances — useful for failover scenarios.
24. What is a NAT Gateway?
A NAT (Network Address Translation) Gateway allows instances in a private subnet to initiate outbound connections to the internet (for software updates, for example) without allowing inbound connections from the internet. It sits in a public subnet and acts as the outbound proxy for private instances.
25. What is Route 53?
Amazon Route 53 is AWS’s scalable DNS (Domain Name System) service. It translates human-readable domain names into IP addresses, routes traffic to your AWS resources (EC2, load balancers, S3), and supports health checks with automatic failover to redirect traffic away from unhealthy endpoints.
26. What is CloudFront?
Amazon CloudFront is AWS’s CDN (Content Delivery Network). It caches your content at edge locations around the world, delivering it to users from the nearest location. This reduces latency, improves load times, and reduces the load on your origin servers. It integrates with S3, EC2, and load balancers.
27. What is a Load Balancer in AWS?
An AWS Load Balancer distributes incoming traffic across multiple EC2 instances or containers to ensure no single instance is overwhelmed. AWS offers three types: Application Load Balancer (ALB) for HTTP/HTTPS traffic, Network Load Balancer (NLB) for high-performance TCP/UDP traffic, and Gateway Load Balancer for third-party virtual appliances.
28. What is AWS Direct Connect?
AWS Direct Connect is a dedicated private network connection between your on-premises data centre and AWS. Unlike a VPN over the public internet, Direct Connect offers consistent, low-latency performance and is commonly used for hybrid cloud setups and large data transfer workloads.
29. What is VPC Peering?
VPC Peering creates a private network connection between two VPCs, allowing resources in each to communicate as if they were on the same network. Peering can connect VPCs in the same AWS account, different accounts, or different regions (inter-region peering).
30. What is AWS Transit Gateway?
Transit Gateway is a network hub that connects multiple VPCs and on-premises networks through a central point. Instead of creating individual peering connections between every VPC, Transit Gateway simplifies the architecture by acting as a cloud router for all connected networks.
AWS Serverless and Containers — Questions 31 to 40
31. What is AWS Lambda and when should you use it?
Lambda is a serverless compute service that runs your code in response to events — HTTP requests, file uploads to S3, database changes, scheduled triggers, and more. You pay only for compute time consumed. Use Lambda for event-driven workloads, microservices, API backends, and automation tasks that run in under 15 minutes.
32. What is API Gateway?
Amazon API Gateway is a fully managed service for creating, deploying, and managing RESTful and WebSocket APIs at any scale. It acts as the front door for backend services — routing requests to Lambda functions, EC2 instances, or any HTTP endpoint. It handles authentication, throttling, caching, and monitoring.
33. What is Amazon ECS?
ECS (Elastic Container Service) is a fully managed container orchestration service that runs Docker containers on AWS. You define tasks (containers with their configuration) and services (how many copies to run), and ECS manages placement, scaling, and health. It integrates with EC2 (you manage the servers) or Fargate (serverless containers).
34. What is the difference between ECS and EKS?
ECS is AWS’s proprietary container orchestration service — simpler to use, tightly integrated with AWS, and best for teams committed to AWS. EKS (Elastic Kubernetes Service) is a managed Kubernetes service — best for teams already using Kubernetes, needing portability, or migrating from on-premises Kubernetes clusters.
35. What is AWS Fargate?
Fargate is a serverless compute engine for containers. It works with both ECS and EKS and removes the need to provision or manage EC2 instances for your containers. You specify CPU and memory at the task level, and Fargate handles the rest — scaling, patching, and infrastructure management.
36. What is Step Functions?
AWS Step Functions is a serverless orchestration service that coordinates multiple AWS services into workflows. You define each step in a state machine, and Step Functions handles retries, error handling, and the sequencing of tasks — ideal for complex, multi-step processes like order processing or data pipelines.
37. What is Amazon SQS?
SQS (Simple Queue Service) is a fully managed message queuing service that decouples application components. Producers send messages to a queue; consumers poll the queue and process them independently. This prevents data loss if a component fails and allows different parts of an application to scale independently.
38. What is Amazon SNS?
SNS (Simple Notification Service) is a fully managed pub/sub messaging service. Publishers send messages to a topic; SNS fans the message out to all subscribers — which can be SQS queues, Lambda functions, email addresses, or HTTP endpoints. It is used for event notifications and triggering multiple downstream processes from a single event.
39. What is Amazon EventBridge?
EventBridge is a serverless event bus that connects applications using events. It receives events from AWS services, your own applications, and third-party SaaS providers, then routes them to targets like Lambda, SQS, or Step Functions based on rules you define. It is the evolution of CloudWatch Events.
40. What is the difference between SQS and SNS?
SQS is a queue — messages are stored until a consumer pulls and processes them (pull model, one consumer per message). SNS is a notification service — messages are pushed to all subscribers simultaneously (push model, many consumers per message). They are often used together: SNS fans out to multiple SQS queues for parallel processing.
AWS Security, DevOps and Advanced Topics — Questions 41 to 50
41. What is AWS KMS?
KMS (Key Management Service) is a managed service for creating and controlling cryptographic keys used to encrypt your data. It integrates with most AWS services — S3, EBS, RDS, Lambda — so you can encrypt data at rest with a single setting. KMS keeps all key operations inside hardware security modules (HSMs).
42. What is AWS CloudTrail?
CloudTrail records every API call made in your AWS account — who made the call, from where, when, and what changed. It is essential for security auditing, compliance, and troubleshooting. CloudTrail logs can be sent to S3 and analysed with Athena or forwarded to CloudWatch for real-time alerting.
43. What is AWS Config?
AWS Config continuously monitors and records the configuration of your AWS resources. It evaluates configurations against your desired rules and flags non-compliant resources. For example, it can alert you if an S3 bucket becomes publicly accessible or if a Security Group opens port 22 to the internet.
44. What is AWS CodePipeline?
CodePipeline is a fully managed CI/CD service that automates the build, test, and deploy stages of your release process. It integrates with CodeCommit, CodeBuild, CodeDeploy, GitHub, Jenkins, and many third-party tools — giving you a complete automated delivery pipeline from code commit to production.
45. What is AWS CloudFormation?
CloudFormation is AWS’s infrastructure-as-code service. You define your AWS resources in a template (JSON or YAML), and CloudFormation provisions and configures them in the correct order. This allows you to version-control your infrastructure, replicate environments, and roll back changes when something goes wrong.
46. What is the difference between CloudFormation and Terraform?
Both are infrastructure-as-code tools, but CloudFormation is AWS-native and only works with AWS resources. Terraform by HashiCorp is cloud-agnostic and can provision resources across AWS, Azure, GCP, and hundreds of other providers. Terraform is preferred for multi-cloud environments; CloudFormation is preferred for AWS-only shops that want deep native integration.
47. What is AWS Elastic Beanstalk?
Elastic Beanstalk is a PaaS (Platform as a Service) that simplifies deploying web applications. You upload your code, and Beanstalk automatically handles capacity provisioning, load balancing, auto-scaling, and health monitoring. It supports Java, .NET, PHP, Node.js, Python, Ruby, Go, and Docker applications.
48. What is Amazon ECR?
ECR (Elastic Container Registry) is a fully managed Docker container registry for storing, managing, and deploying container images. It integrates with ECS, EKS, and CodePipeline, and supports image vulnerability scanning, lifecycle policies to remove old images, and cross-region replication.
49. How does AWS handle high availability?
AWS achieves high availability through multiple Availability Zones (AZs) within each Region — physically separate data centres with independent power, cooling, and networking. Deploying resources across multiple AZs means a failure in one AZ does not take down your application. Services like RDS Multi-AZ, ALB, and Auto Scaling Groups are designed to span AZs automatically.
50. What AWS certifications are most valuable for a cloud engineer in 2026?
The AWS Certified Solutions Architect – Associate is the most widely recognised starting point. From there, the AWS Certified DevOps Engineer – Professional and AWS Certified Solutions Architect – Professional are the most valued for senior roles. Speciality certifications in Security, Machine Learning, and Data Analytics are increasingly sought after in 2026 as organisations mature their cloud practices.
Frequently Asked Questions
What is the best way to prepare for an AWS interview in 2026?
Study core services (EC2, S3, IAM, VPC, RDS, Lambda), practise hands-on in the AWS Free Tier, and review real-world scenarios. Reading interview guides like this one and attempting AWS certification practice exams are both highly effective preparation strategies.
Which AWS services are most commonly asked about in interviews?
EC2, S3, IAM, VPC, RDS, Lambda, CloudWatch, CloudTrail, and Auto Scaling are the most commonly asked about in 2026 interviews. For DevOps roles, CodePipeline, CloudFormation, ECS, and EKS are also frequently tested.
Is AWS certification required to get a cloud job in 2026?
Certification is not always required, but the AWS Certified Solutions Architect – Associate significantly improves your chances. Many employers treat it as a baseline qualification for mid-level cloud roles.
What salary can an AWS engineer expect in 2026?
AWS engineers in the USA earn between $110,000 and $180,000 per year depending on experience and specialisation. Senior solutions architects and DevOps engineers with AWS expertise often exceed $150,000 in major tech markets.
