AWS Interview Questions
Prepare for AWS interviews with these essential questions covering core services, architecture, and best practices. Whether you're interviewing for a cloud engineer role or AWS certification, these questions will help you succeed.
What does S3 stand for and what is it used for?
Answer: S3 stands for Simple Storage Service. It's an object storage service offering scalability, data availability, security, and performance. Use cases include backup and restore, disaster recovery, data archiving, static website hosting, and data lakes. S3 stores data as objects in buckets with virtually unlimited storage capacity.
What is the difference between S3 and EBS?
Answer: S3 is object storage accessed via HTTP/HTTPS, suitable for unstructured data and static files. EBS (Elastic Block Store) is block-level storage attached to EC2 instances, like a hard drive, used for databases and applications requiring low latency. S3 is independent of EC2, while EBS must be attached to an EC2 instance in the same availability zone.
Explain AWS Lambda and its use cases
Answer: AWS Lambda is a serverless compute service that runs code in response to events without provisioning servers. You pay only for compute time used. Use cases include: real-time file processing, stream processing, API backends, IoT data processing, and scheduled tasks. Lambda automatically scales and handles infrastructure management, letting you focus on code.
What is an Auto Scaling Group?
Answer: An Auto Scaling Group automatically adjusts the number of EC2 instances based on demand. It maintains application availability by distributing instances across Availability Zones, replacing unhealthy instances, and scaling capacity up or down based on CloudWatch metrics or schedules. You define minimum, maximum, and desired capacity along with scaling policies.
Explain AWS VPC and its components
Answer: VPC (Virtual Private Cloud) is a logically isolated section of AWS cloud where you launch resources. Components include: Subnets (public/private IP ranges), Internet Gateway (public internet access), NAT Gateway (outbound internet for private subnets), Route Tables (traffic routing), Security Groups (instance-level firewall), Network ACLs (subnet-level firewall), and VPC Peering (connecting VPCs). VPCs provide network isolation and security control.
How does AWS ensure high availability and fault tolerance?
Answer: AWS provides: Multiple Availability Zones (isolated data centers in a region) for redundancy; Multiple Regions globally for disaster recovery; Auto Scaling for handling failures; Load Balancers distributing traffic; S3 and DynamoDB with built-in replication; RDS Multi-AZ deployments; and CloudFront for content delivery. Design principles include: no single points of failure, automated recovery, redundancy, and geographic distribution.
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