AWS is the dominant cloud, and its interviews test the core services (compute, storage, networking, identity) and how you architect with them for scale, reliability, and security. Essential for cloud, DevOps, and backend roles. Here are the AWS interview questions that actually get asked, with answers. (See also our DevOps guide.)
Core services
- EC2 — instances, types, and when to use it.
- S3 — object storage, buckets, storage classes, durability.
- EBS vs S3 vs EFS — block vs object vs file storage.
- Lambda and serverless — when to choose it.
- RDS vs DynamoDB.
Networking & security
- What is a VPC, and subnets (public vs private)?
- Security groups vs network ACLs.
- IAM — users, roles, policies; least privilege.
- What is a NAT gateway, an internet gateway?
Scaling & reliability
- Load balancers (ALB vs NLB) and auto-scaling.
- Regions vs availability zones — designing for high availability.
- CloudFront (CDN); Route 53 (DNS).
- How do you architect a fault-tolerant application?
How to prepare
AWS rounds mix service knowledge with architecture scenarios. Practise explaining service choices and HA design out loud. Greenroom runs spoken technical interviews that follow up on your reasoning. Pair it with our DevOps and system design guides.
Frequently asked questions
What are the most common AWS interview questions?
Common AWS questions cover compute (EC2 instances and types, Lambda/serverless), storage (S3, EBS, EFS and their differences, storage classes), databases (RDS vs DynamoDB), networking (VPC, public vs private subnets, security groups vs NACLs, NAT and internet gateways), identity (IAM users, roles, policies, least privilege), and scaling/reliability (load balancers, auto-scaling, regions vs availability zones, CloudFront, Route 53).
What is the difference between EC2, S3 and EBS?
EC2 is compute — virtual servers you run applications on. S3 is object storage for files and unstructured data, accessed over HTTP with high durability and virtually unlimited capacity. EBS is block storage that attaches to a single EC2 instance like a virtual hard disk for low-latency, persistent volumes. In short: EC2 runs your app, S3 stores objects/files, and EBS provides disk volumes for instances.
What is IAM in AWS?
IAM (Identity and Access Management) controls who can do what in your AWS account. It uses users, groups and roles, with policies (JSON documents) granting specific permissions. Roles let services or users assume temporary permissions without long-lived credentials. The guiding principle is least privilege — granting only the permissions each identity actually needs — which is a frequent interview talking point.
How should I prepare for an AWS interview?
Learn the core services across compute, storage, networking and identity, but focus on architectural thinking — when to choose S3 over EBS, why use a private subnet, how to design for high availability across availability zones, and applying least privilege. Practise explaining service choices and fault-tolerant designs out loud with a voice-based mock interview that follows up.