50 AWS Interview Questions and Answers 2026

Quick Answer: This guide covers the 50 most-asked AWS interview questions and answers for 2026, spanning core services (EC2, S3, VPC, IAM, Lambda), databases, security, high availability, and cost optimization. Each answer is concise and interview-ready — ideal for quick revision before an AWS, Cloud, or DevOps interview.

AWS Fundamentals

What is AWS?
Amazon Web Services is a cloud platform offering on-demand compute, storage, networking, databases, and 200+ managed services on a pay-as-you-go model.
What is a Region and an Availability Zone (AZ)?
A Region is a geographic location; an AZ is one or more isolated data centers within a Region. Deploying across multiple AZs provides high availability.
What is the AWS Shared Responsibility Model?
AWS secures the cloud (hardware, infrastructure); the customer secures what’s in the cloud (data, IAM, configuration, OS patching).
What are the main ways to interact with AWS?
The Management Console (web UI), AWS CLI, SDKs, and Infrastructure as Code (CloudFormation, Terraform).
What is the difference between scalability and elasticity?
Scalability is the ability to handle growth; elasticity is automatically adding/removing resources to match real-time demand.

Compute (EC2, Lambda, Containers)

What is Amazon EC2?
Elastic Compute Cloud provides resizable virtual servers (instances) in the cloud.
What are the EC2 pricing models?
On-Demand, Reserved Instances, Savings Plans, Spot Instances, and Dedicated Hosts.
What are Spot Instances best for?
Fault-tolerant, interruptible workloads (batch jobs, CI, big data) at up to ~90% discount.
What is an AMI?
An Amazon Machine Image — a template (OS + config) used to launch EC2 instances.
What is Auto Scaling?
A service that automatically adjusts the number of EC2 instances based on demand or schedules.
What is AWS Lambda?
A serverless compute service that runs code in response to events without provisioning servers; you pay per request and duration.
What is the difference between ECS, EKS, and Fargate?
ECS is AWS’s container orchestrator, EKS is managed Kubernetes, and Fargate is the serverless compute engine that runs containers for both without managing nodes.
What is an Elastic Load Balancer (ELB)?
A managed load balancer (ALB for HTTP/HTTPS, NLB for TCP/UDP, GWLB for appliances) that distributes traffic across targets.

Storage (S3, EBS, EFS)

What is Amazon S3?
Simple Storage Service — highly durable (11 nines) object storage for files, backups, and static assets.
What are S3 storage classes?
Standard, Intelligent-Tiering, Standard-IA, One Zone-IA, Glacier Instant/Flexible Retrieval, and Glacier Deep Archive — trading cost for access speed.
What is the difference between EBS and S3?
EBS is block storage attached to a single EC2 instance; S3 is object storage accessed over HTTP and shared globally.
What is Amazon EFS?
Elastic File System — a managed, elastic NFS file system that multiple instances can mount simultaneously.
How do you secure an S3 bucket?
Block public access, use bucket policies and IAM, enable encryption (SSE-S3/KMS), enable versioning, and use VPC endpoints.
What is S3 versioning?
Keeping multiple versions of an object to recover from accidental deletes or overwrites.

Networking (VPC, Route 53, CloudFront)

What is a VPC?
A Virtual Private Cloud — your own isolated virtual network within AWS where you define subnets, routing, and security.
What is the difference between a public and private subnet?
A public subnet has a route to an Internet Gateway; a private subnet does not (it uses a NAT Gateway for outbound access).
What is the difference between a Security Group and a NACL?
Security Groups are stateful and operate at the instance level; Network ACLs are stateless and operate at the subnet level.
What is a NAT Gateway?
A managed service that lets instances in a private subnet reach the internet for outbound traffic while blocking inbound connections.
What is Amazon Route 53?
A scalable DNS and domain registration service with health checks and routing policies (weighted, latency, failover, geolocation).
What is Amazon CloudFront?
A global Content Delivery Network (CDN) that caches content at edge locations to reduce latency.
What is VPC Peering vs Transit Gateway?
VPC Peering connects two VPCs directly; Transit Gateway is a hub that connects many VPCs and on-prem networks at scale.

Databases

What is Amazon RDS?
A managed relational database service supporting MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, and Aurora.
What is Amazon Aurora?
AWS’s cloud-native, MySQL/PostgreSQL-compatible database offering higher performance and automated scaling.
What is DynamoDB?
A fully managed, serverless NoSQL key-value and document database with single-digit-millisecond latency.
What is the difference between RDS Multi-AZ and Read Replicas?
Multi-AZ provides high availability via a standby in another AZ; Read Replicas scale read traffic.
What is ElastiCache?
A managed in-memory cache (Redis or Memcached) used to speed up applications.

Security & IAM

What is IAM?
Identity and Access Management — controls who (users/roles) can do what (permissions) on which AWS resources.
What is the difference between an IAM user and an IAM role?
A user is a permanent identity with long-term credentials; a role is assumed temporarily and provides short-lived credentials.
What is the principle of least privilege?
Granting only the minimum permissions required to perform a task.
What is AWS KMS?
Key Management Service — creates and manages encryption keys for encrypting data across AWS services.
What is AWS Secrets Manager vs Parameter Store?
Both store config/secrets; Secrets Manager adds automatic rotation and is purpose-built for secrets, while SSM Parameter Store is simpler and cheaper.
What is a VPC Endpoint?
A private connection from your VPC to AWS services without traversing the public internet.

Monitoring, IaC & Cost

What is Amazon CloudWatch?
A monitoring service for metrics, logs, dashboards, and alarms across AWS resources and applications.
What is AWS CloudTrail?
A service that records all API calls and account activity for auditing and compliance.
What is the difference between CloudWatch and CloudTrail?
CloudWatch monitors performance/health; CloudTrail logs who did what (audit trail).
What is AWS CloudFormation?
AWS’s native Infrastructure as Code service that provisions resources from declarative templates.
How does CloudFormation compare to Terraform?
CloudFormation is AWS-only and native; Terraform is multi-cloud and uses HCL with its own state management.
What is AWS Cost Explorer?
A tool to visualize, understand, and forecast AWS spending.
Name three ways to reduce AWS costs.
Use Savings Plans/Reserved Instances, right-size and turn off idle resources, and adopt Spot Instances and S3 lifecycle policies.

Architecture & Scenario Questions

How do you design a highly available web application on AWS?
Deploy across multiple AZs behind an ALB, use Auto Scaling, a Multi-AZ RDS or DynamoDB, S3/CloudFront for static assets, and Route 53 for DNS failover.
What are the AWS Well-Architected Framework pillars?
Operational Excellence, Security, Reliability, Performance Efficiency, Cost Optimization, and Sustainability.
How do you decouple application components on AWS?
Use SQS (queues), SNS (pub/sub), and EventBridge (event bus) for asynchronous, loosely coupled communication.
How would you secure a multi-account AWS environment?
Use AWS Organizations with Service Control Policies, centralized logging, IAM Identity Center (SSO), and guardrails via AWS Control Tower.
How do you achieve disaster recovery on AWS?
Choose a strategy by RTO/RPO: backup & restore, pilot light, warm standby, or multi-site active-active.
What is Infrastructure as Code and why use it on AWS?
Defining infrastructure in code (CloudFormation/Terraform) for repeatable, version-controlled, auditable provisioning. See our Terraform guide.

Frequently Asked Questions

Are these AWS interview questions suitable for freshers and experienced candidates?

Yes. The fundamentals and core-service questions suit freshers, while the architecture and scenario questions target experienced and DevOps/Cloud-engineer roles.

Which AWS services are most important for interviews in 2026?

EC2, S3, VPC, IAM, Lambda, RDS/DynamoDB, CloudWatch, and Auto Scaling are the most frequently asked, along with container services (ECS/EKS/Fargate) and cost optimization.

How should I prepare for an AWS interview?

Combine these questions with hands-on practice in a free-tier account, understand the Well-Architected Framework, and be ready to design solutions for high availability, security, and cost.