Top 113 AWS Interview Questions and Answers for 2025 (Updated Guide)

Cloud skills show up in almost every software engineer interview today, and AWS Interview Questions are often the deciding factor between candidates. Which services will they ask about, and how do you turn knowledge of EC2, S3, Lambda, IAM, and VPC into convincing answers? This article lays out sample questions, behavioral and scenario-based prompts, system design checklists, security and cost optimization tips, and practice paths. Hence, you feel fully confident and prepared to ace your AWS interview in 2025, impress recruiters with up-to-date knowledge, and secure a high-paying cloud job.

To help you reach those goals, Interview Coder offers an undetectable coding assistant for interviews that simulates real AWS interview questions, delivers focused feedback, and builds the hands-on skills recruiters look for.

What are the Different Types of AWS Interview Questions?

AWS spans compute, storage, networking, security, data, CI CD, observability, containers, and edge services. Interviewers probe across those areas because production systems touch many subsystems. Expect questions that test architecture skills, trade-off reasoning, and hands-on know-how as much as service names and APIs.

Types of AWS Interview Questions You Will Face

• Technical questions about cloud architecture, networking, security, and specific AWS services.
  • Example: How does VPC peering differ from Transit Gateway?
• Scenario-based questions that present a real-world problem and ask you to design a solution or debug an outage.
  • Example: How would you design a multi-region web app with 99.99 percent availability?
• Behavioral questions about teamwork, communication, and leadership.
  • Example: Tell me about a time you rolled back a bad deployment.
• Role specific questions targeted to DevOps, Solutions Architect, Data Engineer, or SRE roles.
  • Example for Data Engineer: How would you design a data lake for petabyte scale with low cost and frequent queries?

Compute Choices: EC2, Lambda, and Elastic Beanstalk Explained

EC2

Gives virtual machines you control:

• OS
• Instance type
• Patching
• Custom networking

Use EC2 for long-running workloads, custom kernels, or when you need GPUs or specialized hardware.

Lambda

Offers serverless functions that scale automatically and reduce ops work. Use Lambda for event-driven tasks, APIs with bursty traffic, or short-lived compute.

Elastic Beanstalk

Sits between EC2 and Lambda. Deploy code and let AWS manage instances and load balancing while you still retain some configuration.

EC2 vs Lambda Interview Focus

• What they might ask: When would you choose EC2 over Lambda?
• What they are looking for: Show you can compare cold start behavior, execution time limits, cost at scale, stateful versus stateless needs, and operational overhead.

Storage Choices: S3, EBS, and EFS, and How to Pick

S3

Object storage for static hosting, data lakes, and backups. Know storage classes, lifecycle rules, versioning, encryption, and eventual consistency for some operations.

EBS

Block storage for single EC2 volumes. It fits databases, boot volumes, and workloads that require consistent IOPS. Consider volume types and provisioning for throughput and latency.

EFS

A network file system mountable by multiple EC2 instances. Use it when you need shared POSIX storage across instances. Think about throughput modes and costs.

EBS vs EFS Interview Focus

• What they might ask: EBS vs EFS: What is the difference in throughput and access pattern?
• What they are looking for: Explain throughput, latency, mount targets, scalability, and when shared file semantics are necessary.

Networking and Security: VPC, Security Groups, NACLs, and IAM

VPC

Gives you an isolated IP space, subnets, route tables, NAT, and gateways. Plan subnets across availability zones for high availability.

Security Groups

Act like stateful firewalls attached to instances. NACLs are stateless and work at the subnet boundary. Use Security Groups for instance-level policies and NACLs for coarse network controls.

IAM

Controls authentication and authorization across users, roles, and services. Know policies, role-based access, trust relationships, and the principle of least privilege. Also, cover encryption keys with KMS and audit trails with CloudTrail.

Security Groups vs NACLs Interview Focus

• What they might ask: How do Security Groups and NACLs differ when troubleshooting connectivity?
• What they are looking for: Show you can reason about attack surface, debug access problems, and craft maintainable access controls.

Observability and Logging: CloudWatch, CloudTrail, and Tracing

CloudWatch

Collects metrics and logs, drives alarms, and provides dashboards. Use structured logs and log aggregation to quickly identify root causes.

CloudTrail

Records API activity for auditing and forensic analysis. Use it to track changes, detect suspicious behavior, and meet compliance needs.

Distributed Tracing (X-Ray / Open Standards)

Helps connect requests across services and find latency hotspots.

Debugging Latency Interview Focus

• What they might ask: How would you debug a sudden spike in latency?
• What they are looking for: Describe correlating traces, metrics, and logs, isolating a component, and testing hypotheses.

Database Choices: RDS, DynamoDB, and Aurora

RDS

Provides managed relational databases with backups, multi-AZ failover, and maintenance. Use RDS for transactional workloads that require SQL and firm consistency.

DynamoDB

Serverless NoSQL designed for massive scale and millisecond latency. Design partition keys, secondary indexes, and think about eventual consistency vs strong consistency on reads.

Aurora

Offers higher performance MySQL and PostgreSQL compatible engines with autoscaling and fast failover. Use Aurora for high-throughput relational workloads.

DynamoDB vs RDS Interview Focus

• What they might ask: When would you select DynamoDB over RDS?
• What they are looking for: Show you can weigh schema complexity, query patterns, consistency, cost, and scaling behavior.

Automation and DevOps: IaC, CI/CD, and Deployment Patterns

CloudFormation and CDK let you define AWS infrastructure as code with native service integration. Terraform gives a multi-cloud IaC approach and state management. CodePipeline, CodeBuild, and CodeDeploy form an AWS native CI CD toolchain. Pair them with testing, canary or blue-green deployments, and automated rollback policies.

Managing Deployments Interview Focus

• What they might ask: How do you manage deployments across dev, staging, and prod without duplicating templates?
• What they are looking for: Explain environment promotion pipelines, parameterization, modular templates, and rollback strategies.

DevOps Tools for Developers: Docker and Kubernetes Basics

Docker packages applications with dependencies so you get consistent builds and deployment. Containers simplify CI CD and resource isolation.

Kubernetes provides orchestration with pod scheduling, service discovery, and self-healing. On AWS, choose EKS for managed Kubernetes or ECS for more straightforward integration with AWS services.

Kubernetes Debugging Interview Focus

• What they might ask: How do you debug a crashing container in Kubernetes?
• What they are looking for: Describe logs, pod events, liveness and readiness probes, and resource limits.

Messaging and Event-Driven Services: SNS, SQS, and EventBridge

SNS sends notifications to many subscribers with pub-sub semantics. SQS decouples producers and consumers with reliable queues and visibility timeouts. EventBridge routes events between AWS services and SaaS with rules. Design for retries, idempotency, dead letter queues, and message ordering when needed.

Decoupling Microservices Interview Focus

• What they might ask: How would you decouple microservices in AWS using managed services?
• What they are looking for: Demonstrate patterns for resilience, back pressure, and ordered processing.

Analytics and Query Services: Athena, Redshift, and QuickSight

Athena queries data directly in S3 with SQL for ad hoc analysis and pay per query. Use schema on read and partitioning to reduce costs. Redshift is a data warehouse for complex analytics and large-scale reporting. Tune distribution keys, sort keys, and spectrum for external queries. QuickSight builds dashboards and visualizations from data sources with embedded analytics options.

Querying Log DaECS vs EKS Interview Focusta Interview Focus

• What they might ask: How do you query log data stored in S3 with low cost and good performance?
• What they are looking for: Explain partitioning, compression, columnar formats, and when to use Athena versus Redshift.

Containers and Orchestration on AWS: ECS, EKS, and Fargate

ECS integrates tightly with AWS and can be simpler to operate. EKS delivers managed Kubernetes for teams already using Kubernetes. Fargate removes server management by running containers serverless. Decide based on team expertise, control needs, and operational overhead.

ECS vs EKS Interview Focus

• What they might ask: When would you choose ECS over EKS for running microservices?
• What they are looking for: Compare control, learning curve, portability, and integration with other AWS services.

Edge Services and CDN: CloudFront and Lambda at the Edge

CloudFront caches content globally to lower latency. Use origin shielding, cache control headers, and signed URLs for access control. Global Accelerator routes traffic over the AWS global network to improve performance for TCP and UDP applications. Lambda at the edge runs functions closer to users for low-latency customization.

Global Performance Interview Focus

• What they might ask: How do you speed up an app for a global audience with cached assets and dynamic personalization?
• What they are looking for: Show knowledge of caching strategies, cache invalidation, TTLs, and edge compute trade-offs.

Cost Management and Governance: Cost Explorer, Budgets, and Trusted Advisor

Cost Explorer shows spend trends and helps identify cost drivers. Budgets sends alerts for thresholds. Trusted Advisor scans for savings opportunities and best practice gaps. Use reserved instances and savings plans for predictable workloads and spot instances for fault-tolerant batch work. Implement tagging and cost allocation for accountability.

Cloud Cost Management Interview Focus

• What they might ask: How do you monitor and reduce cloud costs while keeping reliability?
• What they are looking for: Show you can right-size, use pricing models, and enforce governance with policies and tagging.

Sample System Design Prompts and What to Practice

Practice designing a fault-tolerant API backend, a data lake for analytics, a CI CD pipeline with automated tests, and a multi-region disaster recovery plan. For each exercise, pick services, justify trade-offs for cost, latency, and operational complexity, and describe monitoring and rollback mechanisms. Ask yourself follow-up questions during mock interviews to show depth and systems thinking.

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Top 70 AWS Interview Questions and Answers For 2025

1. What Is AWS, and Why Do Companies Choose It?

AWS, Amazon Web Services, is a cloud computing platform offering compute, storage, database, networking, analytics, machine learning, and many managed services.

Organizations pick AWS for its broad service catalog, global infrastructure of regions and availability zones, mature security controls, and strong partner ecosystem. Companies scale fast, pay for what they use, and accelerate development by offloading infrastructure management to AWS.

2. What Are the Key AWS Components, and What Do They Do?

EC2 provides on-demand virtual machines. S3 is durable object storage for files and backups. RDS manages relational databases like MySQL, PostgreSQL, SQL Server, and MariaDB. IAM controls authentication and authorization. These components form the basic building blocks for most AWS architectures.

3. What Is an EC2 Instance, and How Does It Operate?

An EC2 instance is a virtual machine you launch from an AMI. You pick an AMI, choose an instance type for CPU, memory, storage, and networking, and AWS runs it on the physical host. You manage the OS and applications unless you use managed compute options like ECS Fargate.

4. How Does S3 Differ from EBS, and When Do You Use Each?

S3 is object storage accessed by API or HTTP, ideal for static assets, backups, and data lakes. EBS is block storage attached to EC2, suitable for OS disks and databases that need low-latency IOPS. S3 is globally durable and zone-independent; EBS volumes are tied to a single Availability Zone.

5. How Does AWS Auto Scaling Work?

Auto Scaling adds or removes EC2 instances (or scales services like ECS or DynamoDB) based on policies, CloudWatch metrics, or scheduled actions. It keeps capacity aligned with demand, lowers cost during low traffic, and maintains availability when traffic spikes.

6. What Is the AWS Free Tier, and Which Services Are Included?

The Free Tier gives limited free usage for new accounts for 12 months and some services with always-free limits. It typically includes t-type EC2 hours, S3 storage up to a threshold, Lambda invocations, RDS trial hours, and other starter quotas so you can experiment without immediate cost.

7. What Are Key Pairs in AWS, and How Do They Secure Instances?

A key pair is an RSA or ED25519 public/private key pair. AWS stores the public key on the instance; you use the private key to SSH into Linux instances or decrypt Windows passwords. Key pairs prove identity and replace password-based access for EC2.

8. What Is Elastic Load Balancing, and What Does It Do?

Elastic Load Balancing distributes incoming traffic across targets, EC2, containers, or IP addresses, across multiple Availability Zones. It improves fault tolerance by routing around unhealthy targets, handling SSL/TLS termination, and enabling content-based routing when needed.

9. What Types of Load Balancers Does AWS Offer, and When to Use Each?

Use Application Load Balancer for HTTP/HTTPS and content-based routing, Network Load Balancer for extreme performance and static IPs over TCP/UDP/TLS, and Gateway Load Balancer to insert third-party virtual appliances like firewalls. Each fits different protocols, latency, and scaling needs.

10. How Is Data Transfer Handled and Billed in AWS?

Data transfer costs depend on source and destination: transfers within the same AZ are usually free, cross-AZ have small fees, inter-region and internet egress are charged. Using CloudFront or VPC endpoints can reduce costs and latency for common traffic patterns.

11. What Is Amazon RDS, and Which Database Engines Does It Support?

RDS is a managed relational database service that automates backups, patching, and failover. Supported engines include MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server. Amazon Aurora offers MySQL and PostgreSQL-compatible engines with higher scalability and performance.

12. What Does AWS Identity and Access Management Do?

IAM creates and manages users, groups, roles, and fine-grained policies to grant or deny AWS API access. Use least privilege, roles for services, and MFA for sensitive access. Combine IAM with AWS Organizations and SCPs for centralized governance at scale.

13. What Is Amazon VPC, and How Does It Secure Resources?

VPC is a logically isolated virtual network. You define CIDR ranges, public and private subnets, route tables, security groups, and NACLs to control traffic flow. Use private subnets for databases and public subnets for internet-facing resources to reduce exposure.

14. What Is the Default Subnet Limit in a VPC?

A default soft limit is 200 subnets per VPC. AWS quota service allows you to request increases for production needs.

15. What Is Amazon Route 53, and How Do You Use It?

Route 53 is a DNS and domain registration service that routes users to endpoints based on latency, geolocation, or health checks. Use it to direct traffic to ELBs, CloudFront distributions, or fail over between regions.

16. How Does AWS Help with Backups and Disaster Recovery?

Use point-in-time RDS snapshots, S3 versioning and replication, AWS Backup for centralized policies, and cross-region replication for resilience. For full-site recovery, use AWS Elastic Disaster Recovery to replicate servers to another region and run failover drills.

17. What Is Elastic Beanstalk, and How Does It Simplify Deployment?

Elastic Beanstalk deploys and manages applications by provisioning EC2, load balancers, Auto Scaling, and monitoring. Upload code, and Beanstalk handles environment management. It suits standard web apps that need quick deployment without custom infra automation.

18. Why Use AWS Organizations?

Organizations centralize billing, enable service control policies, and group accounts into OUs for consistent guardrails. Combine it with AWS Control Tower or Landing Zone to enforce security baselines and accelerate secure account provisioning.

19. What Is an AMI, and Why Use It?

An AMI is an image that includes an OS, software, and launch permissions. Save a configured instance as an AMI to launch identical servers quickly. Use encrypted AMIs and share AMIs across accounts or bake AMIs with tools like Packer for reproducible builds.

20. How Do Regions and Availability Zones Relate?

Regions are distinct geographic areas. Each region contains multiple Availability Zones, which are isolated data centers with independent power and networking. Deploy across AZs in a region to survive AZ failures and replicate data across regions for disaster recovery.

21. What Is the Largest Object Size You Can Store in S3?

S3 supports single objects up to 5 terabytes. For large uploads, use a multipart upload to improve reliability and parallelism.

22. Reiterate the Differences Between S3 and EBS and Their Best Use Cases

S3 is ideal for immutable objects, backups, and static content with high durability and global access. EBS serves as block storage for running systems and databases that need consistent, low-latency IOPS. Match service to access patterns: object versus block.

23. How Does Lambda Work, and What Are Typical Use Cases?

Lambda runs functions in response to events with automatic scaling and per-invocation billing. Use it for real-time file processing, API backends via API Gateway, event-driven microservices, scheduled tasks, and light ETL. Use Provisioned Concurrency for predictable latency in production.

24. What Is the Difference Between Security Groups and Network ACLs?

Security groups are stateful, act at the instance level, and allow or deny traffic by rule. NACLs are stateless, apply to subnets, and evaluate numbered regulations in order. Use security groups for instance-level protection and NACLs for an extra subnet-level control layer.

25. What Does CloudFormation Provide?

CloudFormation lets you declare AWS resources in templates, manage stacks, and apply deterministic updates. Use modular templates, change sets, and parameterize to manage environments reproducibly. Consider CDK for higher-level, code-driven infrastructure authoring.

26. How Do You Monitor and Log AWS Resources Effectively?

Use CloudWatch for metrics, dashboards, alarms, and Logs for central log storage. Use CloudTrail to record API calls for auditing. Combine metrics, logs, and traces with X-Ray for distributed tracing and faster root-cause analysis.

27. What Storage Classes Does S3 Offer and When to Use Them?

S3 Standard for frequent access, Intelligent-Tiering for automatic cost optimization, Standard-IA and One Zone-IA for infrequent access, Glacier Instant/Flexible/Deep Archive for long-term archival with different retrieval times. Choose based on access patterns, durability, and retrieval latency.

28. What Is AWS OpsWorks, and Where Does It Fit?

OpsWorks provides Chef and Puppet-managed stacks for configuration automation. It’s useful when you need existing Chef/Puppet workflows integrated with AWS, but most teams now prefer CloudFormation, CDK, or Terraform for modern IaC.

29. What Is AWS Key Management Service, and What Are Its Typical Uses?

KMS creates and manages encryption keys centrally. Use it to encrypt EBS, S3, RDS, and application data. Implement key policies and IAM controls, and use AWS CloudHSM when you require dedicated hardware-backed key storage.

30. How Does AWS Support Hybrid Architectures?

Use AWS Direct Connect for private, lower-latency links to AWS. Use VPN for secure internet-based connections. AWS Outposts and Local Zones bring AWS services and hardware on premises for low-latency, consistent operations with the cloud.

31. What Makes DynamoDB Important?

DynamoDB is a fully managed NoSQL store with single-digit millisecond latency, built-in autoscaling, global tables for multi-region replication, and features like DAX for in-memory caching. It suits real-time apps with predictable access patterns.

32. What Is AWS Elastic Transcoder, and When to Use It?

Elastic Transcoder converts media files into formats suitable for playback on different devices. For large-scale or modern requirements, consider AWS Elemental MediaConvert and MediaPackage for advanced video workflows and streaming.

33. How Does AWS CodeDeploy Help Deploy Applications?

CodeDeploy automates deployments to EC2, on-premises servers, ECS, and Lambda. It supports in-place and blue-green deployments, hooks for lifecycle events, and integrates with CodePipeline for a complete CI/CD flow.

34. What Does AWS CloudTrail Do?

CloudTrail logs AWS API activity and stores events for auditing, compliance, and forensic analysis. Send trails to S3, analyze with Athena, and integrate with CloudWatch for alerts on suspicious activity.

35. How Do You Configure And Manage AWS Load Balancers?

Create listeners for ports and protocols, define target groups, set health checks, and attach certificates for TLS. Use routing rules for ALB content-based routing. Monitor target and LB metrics in CloudWatch and tune timeouts and connection settings as needed

36. What Is the AWS Marketplace, and Why Use It?

Marketplace is a curated catalog of third-party software that you can launch quickly on AWS. It simplifies procurement, licensing, and deployment for databases, security tools, and enterprise applications.

37. What Are the Differences Between Application Load Balancer and Network Load Balancer?

ALB works at layer 7, supports HTTP/HTTPS, WebSocket, and host/path routing. NLB operates at layer 4 for TCP/UDP/TLS, offers static IPs, and has very low latency. Select ALB for advanced routing and NLB for extreme performance and IP-level needs.

38. What's the Difference Between Scaling Up and Scaling Out?

Vertical scaling increases a single node’s resources, like CPU or RAM. Horizontal scaling adds more nodes to spread the load. Databases often need vertical scaling for single-writer workloads; stateless web tiers usually scale horizontally.

39. How Does Amazon ECS Help Manage Containers?

ECS schedules and runs containers on EC2 or with Fargate serverless compute. It integrates with ALB, IAM, CloudWatch, and ECR for images. Choose ECS for tight AWS integration or Fargate to avoid managing servers.

40. What Is AWS Direct Connect, and Where Do You Use It?

Direct Connect provides a private network link from your datacenter to AWS. It offers predictable bandwidth and lower latency compared with internet VPNs and is ideal for bulk data transfer and hybrid workloads.

41. How Do You Debug Performance Issues in AWS?

Start with CloudWatch metrics and logs, check CPU, memory, I/O, and network stats. Use X-Ray for tracing across services. Validate DB query performance, review Auto Scaling behavior, and inspect load balancer health checks to find bottlenecks.

42. What is AWS Snowball, and When to Use It?

Snowball is a physical appliance shipped to you to ingest or export terabytes to petabytes of data when network transfer is impractical. It accelerates migrations and large dataset imports without long transfer windows.

43. How Does AWS Support DevOps Workflows?

AWS provides CodePipeline, CodeBuild, CodeDeploy, and CodeCommit for CI/CD, CloudFormation/CDK for IaC, and CloudWatch for monitoring. Integrate third-party tools and adopt automated testing, deployment pipelines, and infrastructure automation to shorten release cycles.

44. What Role Does CloudWatch Play in Observability?

CloudWatch collects metrics, logs, and events. Create dashboards, alarms, and automated actions. Use Logs Insights for interactive queries and Contributor Insights to find top resources affecting performance.

45. How Do You Manage Versions in Amazon S3?

Enable S3 Versioning on a bucket to preserve every version of objects. Use lifecycle rules to expire old versions and S3 Object Lock for write-once-read-many compliance use cases.

46. What Is AWS Glue, and How Does It Streamline ETL?

Glue is a serverless ETL service that discovers schemas, catalogs metadata, and runs Spark-based jobs to transform and load data into data warehouses or lakes. Use Glue Data Catalog as a central metadata repository for analytics.

47. How Do AWS Step Functions Help Coordinate Workflows?

Step Functions orchestrate serverless workflows with state machines and visual diagrams. They manage retries, error handling, and parallel steps, coordinating Lambda functions, Batch jobs, or ECS tasks for complex business processes.

48. What Benefits Does Amazon CloudFront Provide?

CloudFront caches content at edge locations to lower latency for users worldwide. It integrates with WAF and Shield for security and supports signed URLs, dynamic content acceleration, and origin failover to improve reliability.

49. How Does AWS Secure Multi-Tenant Environments?

AWS isolates tenant workloads via virtualization, VPCs, and IAM. Customers secure their applications with encryption, least privilege IAM, network isolation, and logging. AWS services include controls and compliance attestations to support tenant separation.

50. What Is Amazon Kinesis, and What Are Its Streaming Use Cases?

Kinesis ingests and processes streaming data in real time. Kinesis Data Streams is for custom consumers, Firehose delivers to destinations like S3 and Redshift, and Data Analytics runs SQL over streams for monitoring, clickstream processing, or fraud detection.

51. What Are the Key Considerations for High Availability on AWS?

Distribute across multiple AZs, use Auto Scaling and load balancing, replicate data, design for stateless front ends, and choose managed services with multi-AZ support. Add monitoring, health checks, and automated failover for resilient operations.

52. How Does VPC Peering Work, and When Do You Use It?

VPC peering connects two VPCs privately so instances can communicate via private IPs. Use peering for secure cross-account or cross-region connectivity when you need low-latency private routing and don’t require transitive routing or centralized inspection.

53. What EC2 Instance Types Are Available by Cost Model?

On-demand instances provide flexibility with no commitment. Reserved Instances and Savings Plans offer lower cost for steady-state workloads with 1- or 3-year commitments. Spot Instances offer deep discounts for interruptible, flexible tasks.

54. Which Scaling Approach Fits RDS and Why?

RDS often uses vertical scaling to increase instance size for single-writer workloads, and read replicas to scale reads horizontally. Amazon Aurora provides better horizontal scaling with cluster-based read scaling and serverless options that auto-scale for variable load.

55. How Would You Architect a Scalable Fault-Tolerant Web Application on AWS?

Use Auto Scaling groups across multiple AZs behind an ALB, store static assets in S3 with CloudFront, use RDS Multi-AZ or Aurora for the relational store, add DynamoDB for high-scale NoSQL, cache with ElastiCache, secure with IAM and VPC, and deploy via IaC and CI/CD. Monitor with CloudWatch and use health-driven routing with Route 53.

56. When Should You Pick RDS Instead of DynamoDB?

Choose RDS when you need complex SQL queries, transactions, joins, or a relational schema. DynamoDB is better for massive scale with single-digit millisecond lookups and simpler access patterns.

57. How Do You Create a VPC with Public and Private Subnets?

Create a VPC CIDR, add public and private subnets across AZs, attach an Internet Gateway, and associate a public route table for public subnets. Create a NAT Gateway in a public subnet and route private subnet outbound traffic through it. Apply security groups and NACLs for traffic control.

58. How Would You Handle a Sudden Surge in Traffic?

Use Auto Scaling and pre-warmed load balancers, cache responses with CloudFront and ElastiCache, scale the database with replicas or serverless options, shift traffic with Route 53 or Global Accelerator, and trigger Lambda-driven autoscaling actions from CloudWatch alarms.

59. What Steps Are Involved in an On-Premises to AWS Migration?

Assess workloads, choose a migration strategy (lift-and-shift, re-platform, re-architect), map target architecture, use tools like AWS Application Migration Service or DMS for databases, migrate data, cut over DNS, optimize and secure resources, and validate performance and compliance after migration.

60. How to Design Disaster Recovery for a Critical AWS-Hosted App?

Define RTO and RPO, choose DR strategy (backup and restore, pilot light, warm standby, active-active), enable cross-region replication, automate failover with AWS Elastic Disaster Recovery and Route 53 routing, and schedule regular DR drills to validate procedures.

61. When Would You Use Lambda Functions in an Application?

Use Lambda for lightweight event-driven tasks such as image processing, API endpoints through API Gateway, scheduled jobs, data transformation, and glue logic between services, where you want no server management and pay-per-invocation billing.

62. How Would You Provide End-to-End Encryption for Sensitive Data?

Use HTTPS/TLS for in-transit protection, KMS-managed keys for at-rest encryption in S3, EBS, and RDS, and application-level encryption where only the client can decrypt. Restrict key usage with IAM policies and audit key access with CloudTrail.

63. Describe a Scenario Where Elastic Beanstalk Is the Right Choice.

Elastic Beanstalk fits when you want rapid deployment for standard web apps and do not require complex custom infrastructure. It handles provisioning, load balancing, and autoscaling while letting developers focus on code.

64. How Would You Analyze and Optimize Rising AWS Costs?

Use Cost Explorer and AWS Budgets to find trends, review Trusted Advisor and Compute Savings Plans, convert steady workloads to Reserved Instances, use Spot for flexible jobs, rightsize instances, remove idle resources, and evaluate serverless or managed services where they lower operational cost.

65. How Can You Regain SSH Access to an EC2 Instance if the Key Is Lost?

Attach the root volume to a helper instance, modify authorized_keys to add a new public key, then reattach the volume. Alternatively, use AWS Systems Manager Session Manager if the SSM agent and IAM role were configured, or run AWSSupport-ResetAccess automation to reset access where supported.

66. If VPC DNS Is Not Resolving, What Might Be Wrong, and How Do You Fix It?

Check that the VPC has enableDnsSupport and enableDnsHostnames enabled if you need internal DNS names. Ensure the DHCP option set points to the correct DNS servers and that route tables and security groups permit necessary DNS traffic.

67. How Do You Set Up CD with CodePipeline and CodeBuild?

Push code to CodeCommit or GitHub, create a CodeBuild project with a buildspec to compile and test, create a CodePipeline with Source, Build, and Deploy stages, wire CodeBuild into the Build stage, and connect Deploy to Elastic Beanstalk, ECS, or S3. Trigger pipeline runs on commits to automate delivery.

68. What are the Five Defining Characteristics of Cloud Computing?

On-demand self-service, broad network access, multi-tenancy and resource pooling, rapid elasticity and scalability, and measured service with metered usage and billing transparency.

69. What are the Main Types of Cloud Computing Services?

Infrastructure as a Service provides virtualized compute, storage, and networking. Platform as a Service offers a managed platform for deploying apps. Software as a Service delivers complete hosted applications over the internet.

70. How Do Regions and Availability Zones Impact Architecture and Latency?

Regions let you place resources close to users and meet regulatory needs. Availability Zones allow you to distribute workloads to reduce single-point-of-failure risk. Design with AZ redundancy for high availability and use cross-region replication for disaster recovery and global scale.

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43 More AWS Interview Questions and Answers For 2025

71. CloudWatch Essentials: What CloudWatch Does and Its Core Parts

Amazon CloudWatch is AWS’s monitoring and observability platform for metrics, logs, events, and alarms that helps teams track performance and troubleshoot issues.

• Metrics: Collect numerical time series from EC2, RDS, Lambda, and custom apps.
• Alarms: Watch those metrics and trigger SNS, Auto Scaling, or Lambda when thresholds get crossed.
• Logs: Centralize application and system logs with filter patterns and insights.
• Events/EventBridge: Route state changes and scheduled events to targets for automation and incident response.

72. Lambda Fundamentals: How Serverless Execution Works

AWS Lambda runs code in response to events without managing servers, billing you only for execution time and resources used. It auto-scales per concurrent invocations, supports multiple runtimes, integrates with API Gateway, S3, DynamoDB, and EventBridge, and requires attention to cold start behavior, IAM role permissions, and function timeouts.

73. Elastic Load Balancing: Distributing Traffic Reliably

Elastic Load Balancing distributes incoming requests across targets to increase availability and balance load across Availability Zones.

• Application Load Balancer: Handles HTTP and WebSocket routing with host and path-based rules.
• Network Load Balancer: Provides high throughput and low latency for TCP/UDP.
• Gateway Load Balancer: Supports third-party virtual appliances.

74. CodePipeline CI/CD: Automating a Multi-Tier Delivery Flow

Use AWS CodePipeline to orchestrate source, build, test, and deploy stages for each tier of a multi-tier app. Connect source repos like CodeCommit or GitHub, run builds and tests in CodeBuild, create artifacts, and deploy with CodeDeploy, Elastic Beanstalk, or ECS; include manual approvals or automated integration tests and use separate stages for dev, staging, and prod.

75. Deployment Design: Provision, Configure, Deploy, Scale, Monitor

Design deployments by choosing provisioning tools (CloudFormation, Terraform), configuration management (SSM, userdata, Chef/Ansible), automated deployment pipelines, auto scaling groups, and load balancers for scaling, and CloudWatch plus X Ray for monitoring and tracing. Apply least privilege IAM, immutable deployments when possible, and automated rollback on failed health checks.

76. Infrastructure as Code: Manage Infrastructure with Declarative Files

Infrastructure as Code treats infrastructure definitions like software:

• Templates or code declare resources
• Versions live in source control
• CI validates changes before applying

Use CloudFormation or Terraform to create repeatable, auditable stacks, and apply parameterization, modules, and drift detection.

77. CI/CD Approach in AWS DevOps: Toolchain and Practices

Implement CI/CD by storing code in a version control system, triggering pipeline runs on commits, using CodeBuild for unit and integration tests, and deploying via CodeDeploy, ECS, or Lambda with environment promotions and gated approvals. Integrate secrets via Secrets Manager or Parameter Store, enforce policy via IAM and Config rules, and monitor pipeline health with CloudWatch metrics and pipeline notifications.

78. ECS Value for DevOps: Managed Containers without Kubernetes Overhead

Amazon ECS manages Docker containers on AWS with tight integration to IAM, ELB, CloudWatch, and Auto Scaling, simplifying deployment and lifecycle management when you prefer AWS-managed orchestration. Use Fargate to run containers serverless or EC2-backed clusters for custom AMI needs, and leverage task definitions, service autoscaling, and service discovery.

79. Blue/Green Strategies: Minimize Risk with Dual Environments

Blue-green deployments hold two full environments and switch traffic to the new version once validated. Implement with CodeDeploy, Elastic Beanstalk, or ECS plus an ALB or Route 53 weighted records to shift traffic gradually and enable instant rollback to the previous environment.

80. Why ECS Instead of Kubernetes: Tradeoffs and Simplicity

ECS reduces operational complexity by offering a native AWS container orchestrator without managing control plane components, integrates directly with AWS services, and often provides faster onboarding for teams fully invested in AWS. Kubernetes offers broader portability and a larger ecosystem, so ECS wins when you want simpler management and tighter AWS service integration.

81. Secrets Management in CI/CD: Protect Credentials Safely

Store credentials in AWS Secrets Manager or Systems Manager Parameter Store with KMS encryption, grant least privilege to pipeline roles, and inject secrets into CodeBuild or runtime environments without hardcoding. Rotate secrets automatically with Secrets Manager and audit access via CloudTrail to ensure traceability.

82. Systems Manager in Production: Centralized Operations and Automation

AWS Systems Manager automates patching, runs remote commands, stores parameters securely, and inventories instances across OS and application layers. Use Run Command and State Manager to enforce configuration, Patch Manager for scheduled updates, and Session Manager for secure shellless access with audit logs.

83. CloudFormation and DevOps: IaC for Repeatable Environments

AWS CloudFormation encodes infrastructure as templates, enabling automated provisioning, stack updates with change sets, and rollback on failures. Integrate templates into CI pipelines, use nested stacks or modules, and perform drift detection to keep deployed stacks consistent.

84. Solutions Architect Role: Designing Practical Cloud Systems

An AWS solutions architect designs secure, scalable, and cost-effective systems, advises development and ops teams on service selection and integration, and translates business requirements into technical blueprints and tradeoffs. They lead architecture reviews, enforce best practices, and align solutions with compliance and operational needs.

85. EC2 Security Best Practices: Lock Down Compute Instances

Secure EC2 by applying IAM roles to grant least privilege, use security groups and NACLs to limit network exposure, disable password-based logins in favor of key pairs or Session Manager, and patch instances via Systems Manager. Isolate workloads in private subnets when possible and use encrypted EBS volumes plus CloudTrail logging for forensic needs.

86. Multi-Region Redundancy: Designing for Geographic Resilience

Achieve multi-region redundancy by replicating critical services and data across regions, using RDS read replicas or cross-region automated backups, S3 cross-region replication, Route 53 for geo or failover routing, and designing active-active or active-passive failover strategies. Test failover runbooks regularly and automate infrastructure provisioning with CloudFormation or Terraform.

87. Choosing RDS, DynamoDB, or Redshift: Pick the Right Database

RDS fits transactional workloads needing SQL, joins, and ACID guarantees. DynamoDB suits high-scale, low-latency key-value and document models with serverless scaling. Redshift targets analytical workloads, large-scale reporting, and complex aggregations with columnar storage.

88. Migrating On-Prem to AWS: CRM Example and Steps

Migrate a CRM by assessing dependencies, choosing lift and shift or replatforming patterns, migrating databases via AWS Database Migration Service, moving assets to S3, and setting up networking with Direct Connect if low latency is required. Validate performance and security, run parallel environments for user acceptance, and cut over after testing and stakeholder approval.

89. Building Microservices on AWS: Patterns and Services to Use

Implement microservices by splitting responsibilities, defining APIs with API Gateway or service mesh, running containers on ECS or EKS, or using Lambda for serverless services, and storing data with per-service stores like DynamoDB or RDS. Use EventBridge or Kinesis for asynchronous communication, and centralize logging and tracing with CloudWatch and X Ray.

90. Glue and Lake Formation: Data Catalog and Security for Lakes

AWS Glue provides ETL, crawlers, and a data catalog; Lake Formation adds fine-grained data access control, ingest workflows, and simplified permissions management for a data lake built on S3. Use Glue jobs to transform data and the Glue Catalog as the central metadata store, while Lake Formation enforces table-level and column-level policies.

91. Cost Optimization for High Traffic Apps: Practical Steps

Use Cost Explorer and Budgets for visibility, buy Reserved Instances for steady state compute, use Spot Instances for flexible workloads, enable auto scaling to match demand, and apply caching with CloudFront and ElastiCache to lower origin compute. Apply S3 lifecycle rules and Intelligent Tiering to move cold data to cheaper classes and right-size instances using Trusted Advisor findings.

92. Well-Architected Pillars: Principles for Better Systems

The framework centers on operational excellence, security, reliability, performance efficiency, and cost optimization to guide architecture decisions and tradeoffs. Use the Well Architected Tool to run reviews, document risks, and prioritize improvements aligned to those pillars.

93. Redshift, RDS, S3 Compared: Pick Storage for Each Workload

Use S3 for durable object storage and raw data landing, RDS for transactional workloads and operational databases, and Redshift for fast analytics across large datasets with columnar storage and MPP query engines. Tie them together by landing data in S3, ETL with Glue or EMR, and loading analytics tables into Redshift for BI.

94. Kinesis vs Lambda for Streaming: Choosing the Right Processor

Choose Kinesis when you need durable, ordered, high-throughput streaming with shard-based scaling, replay capability, and complex stream processing; choose Lambda when events are small, occasional, and you prefer a fully managed execution model. Consider ordering needs, replay, throughput, and processing state to decide between stream services and function-based processing.

95. Batch vs Real-Time Processing: When to Use Each

Batch processes large volumes periodically for analytics and historical modeling, while real-time processes individual events immediately for low-latency use cases like fraud detection or personalization. Choose batch for heavy ETL and cost efficiency, and real-time for time-sensitive decisions and streaming analytics.

96. Automating Schema Evolution: Keep Pipelines Resilient

Automate schema evolution using Glue schema registries, dynamic frames that handle missing fields, and contract checks in CI to detect breaking changes early. Integrate validation with AWS Glue Catalog and tools like Deequ for data quality checks and add versioned schemas to enable consumer compatibility tests.

97. Schema on Read vs Schema on Write: Data Lake vs Warehouse

Schema on read stores raw data in S3 and applies structure at query time using Athena or Redshift Spectrum, offering flexibility for diverse sources. Schema on write enforces structure on ingest into RDS or Redshift to ensure consistency for transactional or high-performance analytical queries.

98. Operational Data Store: Fast Operational Analytics Next to the Warehouse

An operational data store holds integrated, near-real-time data for operational reporting. It complements a data warehouse by providing up-to-date views for operations, while the warehouse stores consolidated historical data for BI. Use an ODS to feed dashboards and operational apps requiring current records while offloading heavy analytics to the warehouse.

99. Building a Data Lake on AWS: Services and Steps

Start with S3 as the landing and storage layer, catalog datasets using Glue, run ETL with Glue jobs or EMR, secure access with Lake Formation and IAM, and query with Athena, Redshift Spectrum, or EMR with Spark. Add lifecycle policies, partitioning, and compression for cost and performance, and instrument auditing with CloudTrail.

100. S3 Storage Classes Explained: Match Cost to Access Patterns

S3 Standard handles frequent access and low latency. Standard Infrequent Access reduces cost for less-accessed objects. One Zone IA stores data in a single AZ for lower cost. Intelligent Tiering moves objects automatically between tiers. Glacier and Glacier Deep Archive serve long-term archival with different retrieval times and costs. Choose based on recovery needs, resiliency, and access frequency to minimize storage spend.

101. Global Low Latency Migration: High Availability for a Data Intensive App

For a global, data-intensive app, use EC2 or autoscaling compute across regions, S3 for object storage with CloudFront for CDN, Route 53 for geo routing, and regional read replicas or global databases like Aurora Global Database to reduce latency. Design active-active or read-heavy regional patterns and use Direct Connect for predictable network performance where needed.

102. Disaster Recovery for Tight RPO and RTO: Services and Strategy

To meet a 5-minute RPO and 1-hour RTO, use continuous backups, cross-region replication, and automated provisioning:

• Enable RDS automated backups or Aurora Global Database
• Use S3 replication and AWS Backup to protect files
• Store CloudFormation templates for rapid reprovisioning
• Orchestrate failover with Route 53 health checks and CloudWatch alarms

Test failover playbooks frequently and automate rollback triggers.

103. Scalable Secure Web Infrastructure: Protecting Against DDoS

Combine CloudFront with edge caching, Route 53 for global DNS, Auto Scaling across AZs for capacity, Shield Advanced for DDoS mitigation, and WAF for layer seven filtering to protect applications. Use VPC design best practices, secure endpoints with TLS, and monitor attacks with CloudWatch and GuardDuty to respond promptly.

104. IoT Real-Time Platform: Ingesting Thousands of Sensors Efficiently

Use Kinesis or IoT Core for ingestion, Lambda or Kinesis Data Analytics for lightweight processing, store raw data in S3, and use EMR or managed services for batch analytics and Redshift for reporting. Apply edge processing where possible, shard Kinesis streams to scale, and use Auto Scaling groups or Fargate to handle variable processing loads.

105. Secure Real-Time Financial Analytics: Architecture and Controls

Ingest transactions with Kinesis or Kafka, process with EMR or Kinesis Data Analytics, store refined datasets in Redshift, and enforce strict controls using IAM, KMS encryption, CloudTrail logging, and Config rules. Use private networking, multi-AZ deployments, and continuous compliance checks, plus data masking and tokenization where necessary.

106. Staying Current with AWS: Learning Habits That Work

Follow AWS blogs and release notes, participate in user groups and webinars, experiment in a sandbox account, and track service updates via newsletters and community forums to keep cloud skills fresh. Build small projects to try new services and document lessons in architecture notes to retain knowledge.

107. Explaining AWS Concepts to Non-Technical Stakeholders

Translate technical concepts into business outcomes, use simple analogies for storage, compute, and networking, show cost and risk tradeoffs, and use diagrams that focus on flow rather than implementation detail when presenting to non-technical audiences. Invite questions and provide short demos or visuals to ground the discussion.

108. Motivation for Working with AWS: What Drives You in Cloud Computing

Describe passion for solving scalability and availability challenges, the appeal of rapid innovation, and the satisfaction of delivering measurable business value through cloud architectures. Highlight continuous learning and system design as ongoing motivators for working with AWS technologies.

109. Managing a Challenging Project: Process and Leadership

Prioritize scope, negotiate tradeoffs, maintain clear lines of communication, and break work into incremental milestones with measurable outcomes to keep a complex project on track. Use retrospective feedback and adjust resources when blockers emerge to sustain momentum.

110. Handling Tight Deadlines and Multiple Projects

Prioritize by impact and urgency, delegate when possible, set incremental goals and checkpoints, and communicate dependencies to stakeholders to avoid surprises. Use time boxing and automated pipelines to reduce manual tasks and free time for critical work.

111. What Sets AWS Apart from Other Cloud Providers

AWS stands out through its broad global footprint, deep service catalog across compute, storage, analytics, and machine learning, and rich integrations that let teams build end-to-end systems with native services. The ecosystem, partner network, and maturity of operational tools make it practical to run enterprise-grade workloads.

112. Learning New AWS Services: Practical Onboarding Steps

Start with official docs and quick starts, spin up a cost-controlled sandbox, run tutorials and small PoCs, and integrate the new service into CI pipelines or architecture diagrams to validate fit. Share findings with the team and create runbooks to capture operational practices.

113. Balancing Security and Efficiency in Design

Apply a security-first mindset with IAM least privilege, encryption in transit and at rest, network segmentation, and audit trails, while selecting scalable managed services and caching to keep performance costs down. Automate security checks, use monitoring for behavioral detection, and design for graceful failure to preserve availability under attack.

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