Amazon Web Services (AWS) is the world’s most comprehensive and broadly adopted cloud platform, offering over 200 fully featured services from data centers globally. Since its launch in 2006, AWS has revolutionized the way businesses manage IT infrastructure by providing scalable, reliable, and cost-effective cloud computing resources on-demand.
AWS enables organizations of all sizes, from startups to large enterprises to quickly deploy applications, store data, run analytics, and build advanced machine learning and AI solutions without worrying about managing physical servers.
Its global network of regions and availability zones ensures high performance, fault tolerance, and security, making AWS a leader in driving digital transformation worldwide. This article covers 50+ AWS interview questions and answers designed to help candidates understand and excel in cloud technology roles.
1. What do you know about AWS Region?
AWS Regions are geographically separate locations where AWS data centers are set up around the world. Each region contains multiple isolated data centers called Availability Zones, allowing users to build applications that are distributed and resilient to failures in a single location.
2. What are the important components of IAM?
The important components of IAM (Identity and Access Management) include Users (individual accounts), Groups (collections of users), Roles (temporary permissions for users or AWS services), and Policies (rules that define access permissions). These help secure AWS resources and manage who can access what.
3. What are the important points about AWS IAM?
Important points about AWS IAM include: IAM is free to use; it helps control access to AWS resources safely; you can grant restricted permissions with policies; it supports multi-factor authentication for added security; and you can integrate IAM with external identity providers such as corporate directories.
4. What are the important features of Amazon S3?
The main features of Amazon S3 are high durability (99.999999999%), high availability, unlimited scalable storage, several storage classes for different needs, built-in encryption, fine-grained access controls, easy lifecycle management policies, and seamless integration with other AWS services.
5. What is the scale of durability in Amazon S3?
Amazon S3 is designed for $$99.999999999\%$$ durability (also called “eleven 9s”), meaning your data has an extremely low chance of being lost. AWS achieves this durability by automatically storing copies of your data across multiple devices and facilities in a region.
6. What are the Consistency levels supported by Amazon S3?
Amazon S3 supports two main consistency levels: strong read-after-write consistency for new objects and overwrite/deletes, and eventual consistency for some edge scenarios. This means you immediately see new data after you upload or update it, improving reliability for cloud applications.
7. What are the different tiers in Amazon S3 storage?
The main S3 storage tiers include S3 Standard (for frequent access), S3 Intelligent-Tiering (automatic cost optimization), S3 Standard-IA (infrequent access), S3 One Zone-IA (infrequent access in a single zone), S3 Glacier Instant Retrieval, S3 Glacier Flexible Retrieval, and S3 Glacier Deep Archive (archival, lowest cost).
8. How will you upload a file greater than 100 megabytes in Amazon S3?
For uploading a file greater than 100 megabytes in S3, it is best practice to use the “multipart upload” feature. This breaks your file into smaller parts, uploads them in parallel, and then combines them in S3, improving speed and reliability for large files.
9. What happens to an Object when we delete it from Amazon S3?
When an object is deleted from Amazon S3, it is marked as deleted and no longer accessible. If versioning is enabled, only the latest version is removed (but older versions remain); if versioning is off, the object is permanently deleted from the storage.
10. What is the use of Amazon Glacier?
Amazon Glacier is used for archiving data that you rarely or never access but need to keep for long-term storage. It offers very low-cost storage, with retrieval times ranging from minutes to hours, making it ideal for backups, compliance, and digital preservation.
11. Can we disable versioning on a version-enabled bucket in Amazon S3?
Once versioning is enabled on an S3 bucket, it cannot be fully disabled—only suspended. Suspending versioning stops the creation of new versions, but previous versions are retained.
12. What are the use cases of Cross Region Replication Amazon S3?
Use cases for S3 Cross Region Replication (CRR) include regulatory compliance (data residency), disaster recovery, reducing latency for global users, sharing data between AWS accounts, and supporting multi-region applications that require synchronized datasets.
13. Can we do Cross Region replication in Amazon S3 without enabling versioning on a bucket?
Cross Region Replication in S3 requires versioning to be enabled; CRR cannot be set up on buckets without versioning. If you want replication without versioning, you must use custom automation like the AWS CLI `aws s3 sync` command.
14. What are the different types of actions in Object Lifecycle Management in Amazon S3?
Object Lifecycle Management in S3 provides actions like object expiration (delete), transition to lower-cost storage tiers (such as Glacier), noncurrent version expiration (delete previous versions), and abort incomplete multipart uploads.
15. How do we get higher performance in our application by using Amazon CloudFront?
Amazon CloudFront improves application performance by caching content at global edge locations, reducing latency and delivering content faster to users by serving it from nearby servers.
16. What is the mechanism behind Regional Edge Cache in Amazon CloudFront?
Regional Edge Cache in CloudFront acts as an intermediate cache layer between origin and edge locations, increasing cache hit rates and reducing origin server load to further speed up content delivery.
17. What are the benefits of Streaming content?
Streaming content enables real-time delivery of audio/video to users with lower buffering, adaptive bitrate, efficient bandwidth usage, and improved user experience on slower networks.
18. What is Lambda@Edge in AWS?
Lambda@Edge is an AWS feature allowing custom code (Lambda functions) to run at global CloudFront edge locations, enabling dynamic content transformation, security checks, and personalized user experiences as requests are processed near the user.
19. What are the different types of events triggered by Amazon CloudFront?
Amazon CloudFront can trigger events such as viewer request, origin request, origin response, and viewer response, allowing Lambda@Edge functions to alter or inspect content at each stage.
20. What is Geo Targeting in Amazon CloudFront?
Geo Targeting in CloudFront allows customization or restriction of web content for users based on their geographic location, helping deliver relevant experiences or comply with regulatory requirements.
21. What are the main features of Amazon CloudFront?
The main features of Amazon CloudFront are global edge locations for faster content delivery, support for both dynamic and static web content, custom caching policies, SSL/TLS secure content delivery, deep integration with AWS services, custom domain support, real-time metrics and logging, security features such as AWS Shield and WAF, origin access control, geo restrictions, Lambda@Edge for custom logic, multiple origin support, and streaming media delivery.
22. What are the security mechanisms available in Amazon S3?
Amazon S3 provides strong security with encryption (data at rest and in transit), fine-grained access policies (IAM, bucket and object policies), VPC endpoints for secure network paths, public access blocking, auditing tools, and data classification/monitoring using Amazon Macie.
23. What are the benefits of AWS Storage Gateway?
AWS Storage Gateway offers seamless hybrid cloud storage integration, local caching for low-latency access, support for standard storage protocols (NFS, SMB, iSCSI), cost savings by leveraging elastic AWS storage, robust security, simple management, and easy backup and data recovery options.
24. What are the main use cases for AWS Storage Gateway?
Main use cases for AWS Storage Gateway involve backup and archival from on-premises to cloud, disaster recovery, extending on-premises storage capacity, enabling cloud-based analytics, tape replacement, and seamless hybrid cloud workflows.
25. What is AWS Snowball?
AWS Snowball is a physical device offered by AWS for transferring large amounts of data into or out of AWS. It is secure, rugged, and designed for fast, cost-effective migration of data, especially helpful when network transfer is too slow or costly.
26. What are Spot instances in Amazon EC2?
Spot instances in Amazon EC2 are spare compute instances available at discounted rates compared to On-demand pricing. They are suitable for fault-tolerant and flexible workloads, but can be interrupted by AWS when capacity is needed elsewhere.
27. What is the difference between Spot Instance and On-demand Instance in Amazon EC2?
Here’s the difference:
| Feature | Spot Instance | On-demand Instance |
|---|---|---|
| Pricing | Much lower, variable rates | Fixed rates |
| Availability | May be interrupted by AWS | Always available unless manually stopped |
| Use Case | Cost-sensitive, flexible jobs | Reliable, mission-critical jobs |
28. What are the different types of load balancing options provided by Amazon Elastic Load Balancing (ELB)?
ELB provides Classic Load Balancer (CLB), Application Load Balancer (ALB), Network Load Balancer (NLB), and Gateway Load Balancer, tailored for diverse networking needs such as HTTP/HTTPS, TCP, and network appliances integration.
29. What are the main features of Classic Load Balancer in EC2?
The main features of Classic Load Balancer are basic round-robin load distribution for HTTP, HTTPS, and TCP traffic, health checks, SSL termination, and simple scaling. It is suited for simple or legacy applications.
30. What are the main features of Application Load Balancer (ALB) in Amazon EC2?
Application Load Balancer features include advanced routing (based on request path, host, headers), support for HTTP/HTTPS, container integration (target groups), authentication, web application firewall (WAF), and real-time metrics. ALB is ideal for modern web applications needing flexible request handling.
31. What is the difference between Volume and Snapshot in Amazon Web Services?
An EBS Volume is a durable, block-level storage device that can be attached to EC2 instances for use as their disks. A Snapshot is a point-in-time, incremental backup of a volume, useful for backup and disaster recovery. Volumes store live data; snapshots save a copy of the volume for later restoration or duplication.
32. What are the two main types of Volume provided by Amazon EBS?
The two main types of EBS volumes are SSD-backed (General Purpose SSD, Provisioned IOPS SSD) for high IOPS and transactional workloads, and HDD-backed (Throughput Optimized HDD, Cold HDD) for high throughput workloads and less frequent access.
33. What is the difference between Instance Store and EBS?
Instance Store provides temporary storage physically attached to the host running the EC2 instance, and data is lost when the instance is stopped or terminated. EBS offers persistent, network-attached storage that retains data even if the instance is stopped or terminated and allows snapshots for backup.
34. What is an Elastic IP Address?
An Elastic IP Address is a static, public IPv4 address designed for dynamic cloud computing, allowing users to mask instance or service failures by remapping the address to another instance in an account.
35. What are the benefits of using a Virtual Private Cloud in AWS?
Benefits of using a Virtual Private Cloud (VPC) include network isolation, customizable IP address ranges, secure access control, subnet creation, connectivity options (VPN, Direct Connect), and scalable network architectures for enhanced security and management.
36. What is a Placement Group in EC2?
A Placement Group in EC2 is a logical grouping of instances within a region that helps improve performance by supporting three strategies: Cluster (proximity for high throughput), Spread (reduces simultaneous failures), and Partition (distributes across hardware).
37. What are the main options available in Amazon CloudWatch?
Amazon CloudWatch provides options for collecting and visualizing system metrics, custom log monitoring, setting alarms, automatic actions, dashboards, anomaly detection, service and resource tracking, and integration with AWS resources.
38. What is a Serverless application in AWS?
A Serverless application in AWS is one where code runs without managing servers, with resources automatically provisioned, scaled, and billed based on usage. AWS handles all infrastructure behind the scenes.
39. How will you manage and run a serverless application in AWS?
To manage and run a serverless application in AWS, use AWS Lambda for code execution, API Gateway for HTTP endpoints, S3 for storage, DynamoDB for data, CloudFormation or SAM for deployment, and CloudWatch for monitoring.
40. What is AWS Lambda?
AWS Lambda is a serverless compute service that runs code in response to events, automatically managing resources so developers just upload their function code, set a trigger, and AWS scales and executes as needed—charging only for actual execution time.
41. What are the main use cases for AWS Lambda?
Main use cases for AWS Lambda include building serverless websites, processing uploaded files (like images or documents), real-time data analytics, scheduled jobs (cron tasks), backend APIs for web and mobile apps, batch processing, log analysis, IoT data processing, automating backups, and integrating other AWS services.
42. How does AWS Lambda handle failure during event processing?
AWS Lambda automatically retries event processing up to two more times for asynchronous events if there is a failure, and supports dead-letter queues or destinations for capturing failed events. You can also configure custom error handling, including sending failed events to SQS, SNS, or EventBridge for further analysis.
43. What are the different routing policies available in Route 53?
The main routing policies in Route 53 are: Simple, Failover, Geolocation, Geoproximity, Latency-based, Weighted, Multivalue Answer, and IP-based. Each policy helps control traffic flow to resources based on specific criteria like location, health, performance, or randomization.
44. What are the main benefits of using Amazon DynamoDB?
Amazon DynamoDB’s benefits include fully managed and serverless operation, automatic scaling, single-digit millisecond latency, built-in high availability and durability, no limits to scaling, flexible data access, integrated security, and cost-effective billing.
45. What is the basic Data Model in Amazon DynamoDB?
The basic data model in DynamoDB uses tables, each with items (records), and each item consists of attributes (fields). Every item must have a primary key, which can be a simple key (partition key) or a composite key (partition key + sort key).
46. What are the different APIs available in Amazon DynamoDB?
DynamoDB provides APIs for low-level data operations (PutItem, GetItem, UpdateItem, DeleteItem, Scan, Query), table management (CreateTable, DeleteTable), batch operations (BatchGetItem, BatchWriteItem), and stream event registration.
47. When should we use Amazon DynamoDB vs. Amazon S3?
Use DynamoDB when you need fast, low-latency, structured NoSQL database access or transactional workloads. Use S3 for unstructured data storage, large files, backups, media, or archival content.
48. What is the use of Amazon ElastiCache?
48. Amazon ElastiCache is a managed caching service (for Redis or Memcached) that helps improve application performance by storing frequently accessed data in-memory, reducing database load, and speeding up data retrieval.
49. What are the use cases for Amazon Kinesis Streams?
Amazon Kinesis Streams use cases include real-time analytics, collecting and processing log or event data, clickstream analytics, IoT telemetry, financial transaction monitoring, social media data collection, and machine learning data pipelines.
50. What is the difference between Amazon SQS and Amazon SNS? Bonus Questions
Here’s the difference:
| Feature | Amazon SQS | Amazon SNS |
|---|---|---|
| Type | Message queue (pull-based) | Pub/sub topic (push-based) |
| Delivery | Ordered delivery, messages to single consumer | Broadcast messages to multiple subscribers |
| Use Case | Decoupling microservices, backend tasks | Fan-out, multi-system notifications, alerts |
51. What is Alexa for Business from AWS?
Alexa for Business is an AWS service for managing Alexa-enabled devices in organizations. It lets businesses automate meeting rooms, office workflows, and schedules, enabling voice control for work tasks.
52. What are custom skills in Alexa?
Custom skills in Alexa are voice responses and actions developers create specifically for their needs, allowing voice commands to trigger unique apps, business workflows, or integrations beyond standard Alexa abilities.
53. What is AWS Deep Learning AMI?
AWS Deep Learning AMI is a pre-configured Amazon Machine Image containing popular deep learning frameworks (TensorFlow, PyTorch, MXNet, etc.), drivers, and tools to help users quickly start machine learning experiments or development on EC2.
