Real-world AWS interview scenarios with expert answers to help you ace your next cloud job in 2025!
Question: 1
Your web application is hosted behind an Application Load Balancer (ALB) with an Auto Scaling Group (ASG). Suddenly, a large number of file downloads start happening, causing the ASG to scale out unnecessarily. You need to ensure that Auto Scaling does not trigger based on download traffic while keeping your application responsive.
a. What temporary fixes can you apply immediately to prevent unnecessary scaling?
b. What long-term solutions would you implement to ensure downloads don’t impact Auto Scaling?
Answer:
a. The fastest way to stop unnecessary scaling is to disable the Auto Scaling policy that is causing it.
b. Modify Auto Scaling metrics to scale based on CPU utilization or Request Count per Target instead of NetworkIn/NetworkOut.
Question: 2
Your application is deployed globally, but due to compliance or security reasons, you need to block access from specific countries while ensuring minimal disruption. How would you achieve this in AWS efficiently?
Answer:
a. AWS WAF (Web Application Firewall) allows you to block requests from certain countries using Geo-Match Rules. This method is useful if you want to completely deny access from restricted regions.
b. Instead of blocking, you can redirect users from restricted countries to another page using AWS Route 53 Geolocation Routing.
Question: 3
Your company runs a global e-commerce website that serves high-resolution product images and videos to users worldwide. Recently, customers in certain regions have reported slow content delivery and high latency, especially during peak hours. How would you optimize the architecture to improve performance, reduce latency?
Answer:
To improve performance and to reduce latency Use a Content Delivery Network. Distribute content across global edge locations to serve users from the nearest location instead of the origin server.
Question: 4
Your company needs to migrate several terabytes of data from an on-premises data center to AWS. Given the need for a secure and efficient transfer method, which AWS service would you choose, and why?
Answer:
For securely and efficiently transferring several terabytes of data from an on-premises data center to AWS, I would use AWS Snowcone.
Why AWS Snowcone?
Designed for Limited Connectivity → Works well in locations with low or no network bandwidth.
Secure Data Transfer → Uses AES-256 encryption and supports AWS OpsHub for management.
Compact & Durable → Small, portable, and rugged device, ideal for remote or harsh environments.
Edge Processing → Can run lightweight compute tasks before transferring data.
Question: 5
Your company runs a data processing application on an EC2 instance inside a private subnet in AWS. The application needs to regularly transfer large amounts of data to and from an S3 bucket for storage and analysis. How would you configure the network and permissions to enable the EC2 instance to securely transfer data to S3 while meeting the security and cost requirements?
Answer:
When an EC2 instance in a private subnet needs to access S3, the main challenge is that it does not have direct internet access. Instead of exposing it to the internet, we can use a VPC Endpoint for S3 along with an IAM Role to ensure security and cost savings.
S3 Gateway VPC Endpoint: This allows private communication between EC2 and S3 without using the internet.
This is secure and avoids extra data transfer costs.
Question: 6
Your organization manages multiple AWS accounts for different teams. The Security Team (Account A) stores critical audit logs in an S3 bucket that should only be accessed by authorized users.
One day, the Application Team (Account B) reports that their automated reporting system, which depends on these audit logs, is failing due to insufficient permissions. how would you diagnose and resolve this issue while ensuring that the Application Team gains the necessary read-only access without compromising security?
Answer:
To grant secure, least-privilege access from Account B (Application Team) to an S3 bucket in Account A (Security Team) without creating IAM users, we can use IAM Role-Based Cross-Account Access.
Create an IAM Role in Account A → Allow Account B to Assume the Role
Assume the Role from Account B
IAM Role + Trust Policy allows secure cross-account access.
Question: 7
Your company runs a data processing application on an EC2 instance, where 100MB files are uploaded, transformed, and stored in S3. How would you migrate this workload to a serverless architecture, ensuring cost optimization, scalability, and efficient handling of 100MB files?
Answer:
AWS Lambda is a serverless option, don’t need to manage infrastructure. AWS Lambda has a 50MB direct payload limit and a 15-minute execution limit, making direct processing of large files challenging.
To migrate 100MB file processing from EC2 to a serverless architecture
Use Amazon S3 as the File Storage & Event Trigger : Upload files to S3, which acts as the storage layer. Configure S3 Event Notifications to trigger an AWS Lambda function when a file is uploaded.
Process Large Files in AWS Lambda : Since Lambda has a 50MB direct payload limit, the function downloads the file from S3 instead of receiving it directly. Use a high-memory Lambda configuration (e.g., 10GB RAM) to process large files efficiently.
Question: 8
Your company operates a mission-critical application that relies on an Amazon RDS database. Recently, a natural disaster caused an entire Availability Zone (AZ) to go down, leading to database downtime and service disruptions. How would you design your RDS database architecture to ensure automatic failover, high availability, and minimal downtime in the event of an AZ failure or disaster? What AWS features would you use to achieve this?
Answer:
To ensure high availability and disaster recovery for Amazon RDS, use Multi-AZ Deployment.
Enable Multi-AZ for RDS: AWS automatically creates a standby replica in a different Availability Zone (AZ).
Automatic Failover During AZ Failure: if the primary AZ fails, RDS automatically switches to the standby replica.
Use Read Replicas for Performance & DR: Deploy cross-region read replicas to improve disaster recovery.
Backup Strategy: Enable automated backups and manual snapshots for additional protection.
Question: 9
Your company runs a multi-instance web application behind a load balancer. Users have reported unexpected logouts and inconsistent session behavior when navigating the app. The issue occurs when requests from the same user are sent to different backend servers, causing session data to be lost. How would you design a solution in AWS to ensure that a user’s requests are consistently routed to the same backend server during their session?
Answer:
To ensure session persistence for users in a load-balanced environment, we can use Sticky Sessions with an Application Load Balancer (ALB).
Enable Sticky Sessions on the Load Balancer: For ALB: Enable target group-based stickiness using a load balancer-generated cookie.
Configuring Sticky Sessions in AWS: In ALB Target Groups, enable “Stickiness” and define the cookie duration.
Question: 10
Your security team has noticed unauthorized API calls being made in your AWS environment. Some resources were modified or deleted, but no one in the team admits to making these changes. You need to identify who made the changes, from where, and when to prevent future incidents. What AWS service would you use to investigate the issue, and how would you configure it to enhance security monitoring?
To investigate unauthorized API activity in AWS, use AWS CloudTrail, which records all API actions across your AWS account.
Enable CloudTrail Logging: CloudTrail automatically logs all API calls made via the AWS Management Console, SDKs, CLI, and other services.
Analyze CloudTrail Logs: Use AWS CloudTrail Event History to check who made the changes, when, and from which IP address.
Enhance Security Monitoring: Enable CloudTrail Insights to detect unusual activity (e.g., a sudden spike in API calls).