Cloud Engineer • Behavioral • medium

Describe a time when you had to push back on a client's architectural request because it was not following cloud security best practices. How did you handle it?

#Communication #Consulting #Security

Practice

Cloud Engineer • Behavioral • medium

Describe a situation where you had to work under a very tight deadline to deliver a cloud infrastructure project for a client. How did you prioritize your tasks?

#Delivery #Prioritization #Stress Management

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you had a disagreement with a senior engineer or architect regarding a technology choice. How was it resolved?

#Conflict Resolution #Teamwork #Communication

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you made a critical mistake in a production environment. What was the impact, and how did you recover and learn from it?

#Accountability #Incident Management #Continuous Improvement

Practice

Cloud Engineer • Behavioral • easy

How do you keep yourself updated with the rapidly changing cloud technologies, and how do you apply this learning to client projects?

#Continuous Learning #Adaptability #Consulting

Practice

Cloud Engineer • Coding • easy

Write a SQL query to find the second highest salary from an 'Employee' table. (A common Infosys baseline data question).

#SQL #Database Queries

Practice

Cloud Engineer • Coding • easy

Given an array of integers, write a function to move all zeros to the end of the array while maintaining the relative order of the non-zero elements. Do this in-place.

#Arrays #Two Pointers

Practice

Cloud Engineer • Coding • easy

Write a function to find the first non-repeating character in a string. Return its index. If it does not exist, return -1.

#Strings #Hash Maps

Practice

Cloud Engineer • Coding • medium

Write a Python script using Boto3 to find and delete all unattached EBS volumes in a specific AWS region to help reduce client costs.

#Python #Boto3 #AWS EC2 #Cost Optimization

Practice

Cloud Engineer • Coding • easy

Write a Bash script that parses a web server access log file, counts the number of HTTP 500 errors, and outputs the top 5 IP addresses generating these errors.

#Bash #Linux #Log Analysis

Practice

Cloud Engineer • System Design • hard

Design a scalable log ingestion and analytics system for a microservices architecture generating 5TB of logs daily.

#Logging #Big Data #Elasticsearch #Kafka

Practice

Cloud Engineer • System Design • medium

Design a secure and scalable architecture for a web application that requires processing large amounts of user-uploaded images asynchronously.

#Asynchronous Processing #Message Queues #AWS S3 #AWS SQS

Practice

Cloud Engineer • System Design • medium

Design an API Gateway architecture for a client transitioning from a monolith to microservices. How do you handle authentication, rate limiting, and routing?

#API Gateway #Microservices #Security

Practice

Cloud Engineer • System Design • hard

Explain the concept of RTO (Recovery Time Objective) and RPO (Recovery Point Objective). How do they influence your Disaster Recovery strategy in AWS?

#Disaster Recovery #AWS #Architecture

Practice

Cloud Engineer • System Design • medium

Design a CI/CD pipeline for deploying a containerized application to an Azure Kubernetes Service (AKS) cluster.

#CI/CD #Azure #AKS #Jenkins/GitHub Actions

Practice

Cloud Engineer • System Design • hard

Design a highly available, fault-tolerant architecture for a monolithic legacy application being migrated to the cloud using a 'Lift and Shift' approach.

#High Availability #Auto Scaling #Disaster Recovery

Practice

Cloud Engineer • Technical • medium

What is a 'cold start' in serverless computing (e.g., AWS Lambda), and what strategies would you use to mitigate it for a latency-sensitive API?

#Serverless #AWS Lambda #Performance Optimization

Practice

Cloud Engineer • Technical • medium

What are Azure Resource Manager (ARM) templates, and how do they compare to Terraform? Why might a client choose one over the other?

#Azure #ARM #Terraform

Practice

Cloud Engineer • Technical • hard

How do you configure cross-account access in AWS so that a user in Account A can access an S3 bucket in Account B securely?

#AWS IAM #Cross-Account Access #S3

Practice

Cloud Engineer • Technical • easy

What is the difference between AWS CloudTrail and Amazon CloudWatch?

#AWS #Monitoring #Auditing

Practice

Cloud Engineer • Technical • medium

How do you handle secrets (like database passwords or API keys) in a cloud-native application to ensure they are not hardcoded in source code?

#Secrets Management #AWS Secrets Manager #Azure Key Vault

Practice

Cloud Engineer • Technical • medium

In Terraform, what is the difference between 'count' and 'for_each' when creating multiple instances of a resource?

#Terraform #HCL

Practice

Cloud Engineer • Technical • medium

Explain how you would design a secure AWS VPC architecture for a client's 3-tier web application, ensuring the database is completely isolated from the public internet.

#AWS #VPC #Subnets #NAT Gateway

Practice

Cloud Engineer • Technical • easy

What are the differences between Azure Blob Storage access tiers (Hot, Cool, Archive)? How do you automate the lifecycle management of these blobs?

#Azure #Blob Storage #Cost Optimization

Practice

Cloud Engineer • Technical • hard

What are Kubernetes Ingress controllers, and how do they differ from a LoadBalancer service type?

#Kubernetes #Networking #Ingress

Practice

Cloud Engineer • Technical • medium

Compare AWS RDS Multi-AZ deployments with Read Replicas. When would you use each?

#AWS RDS #Databases #High Availability

Practice

Cloud Engineer • Technical • medium

A Kubernetes pod is stuck in the 'CrashLoopBackOff' state. Walk me through your step-by-step troubleshooting process.

#Kubernetes #Troubleshooting #Docker

Practice

Cloud Engineer • Technical • medium

How do you optimize a Dockerfile to reduce the final image size and improve security for a Node.js microservice?

#Docker #Microservices #Security

Practice

Cloud Engineer • Technical • medium

Explain the difference between IAM Policies, S3 Bucket Policies, and S3 ACLs. If an IAM policy allows access but a Bucket policy denies it, what is the effective permission?

#AWS IAM #S3 #Security

Practice

Cloud Engineer • Technical • medium

How do you manage Terraform state files in a multi-developer team environment to prevent concurrent modification and state corruption?

#Terraform #State Management #AWS S3 #DynamoDB

Practice

Cloud Engineer • Technical • easy

What is the difference between an AWS Application Load Balancer (ALB) and a Network Load Balancer (NLB)? When would you choose one over the other for an enterprise migration?

#AWS #Load Balancing #OSI Model

Practice

Cloud Engineer • Technical • hard

In Jenkins, what is a Shared Library, and how does it help in managing CI/CD pipelines across multiple projects?

#Jenkins #CI/CD #Automation

Practice

Cloud Engineer • Technical • medium

How do you ensure idempotency when writing Ansible playbooks for server configuration?

#Ansible #Automation #Idempotency

Practice

Cloud Engineer • Technical • medium

Explain how AWS Route 53 routing policies work. When would you use Latency-based routing versus Geolocation routing?

#AWS Route 53 #DNS #Global Architecture

Practice

Cloud Engineer • Technical • easy

Explain the difference between a Security Group and a Network ACL in AWS.

#AWS #Security #VPC

Practice

Data Engineer • Behavioral • medium

How do you manage communication and ensure alignment when working in a distributed model with onshore and offshore teams?

#Communication #Agile #Global Delivery Model

Practice

Data Engineer • Behavioral • medium

Tell me about a time you had a disagreement with a client regarding a technical architecture choice. How did you resolve it?

#Client Communication #Conflict Resolution #Consulting

Practice

Data Engineer • Behavioral • medium

Describe a situation where you had to quickly learn a new technology to deliver an urgent project requirement.

#Adaptability #Continuous Learning #Delivery

Practice

Data Engineer • Coding • medium

Write a Python script to read a large CSV file (10GB) that doesn't fit into memory, filter rows based on a condition, and write to a new file.

#Python #Generators #File I/O #Memory Management

Practice

Data Engineer • Coding • medium

Write a SQL query to find the 3rd highest salary from an Employee table without using the LIMIT keyword.

#Window Functions #Subqueries #DENSE_RANK

Practice

Data Engineer • Coding • medium

Write a Python function to flatten a deeply nested JSON object/dictionary into a single-level dictionary.

#Python #Recursion #Data Structures #JSON

Practice

Data Engineer • Coding • medium

Write a SQL query to delete duplicate rows from a table, keeping only the record with the lowest ID.

#CTEs #ROW_NUMBER() #Data Cleansing

Practice

Data Engineer • Coding • easy

Write a SQL query to find employees who earn more than their direct managers.

#Self Join #Filtering

Practice

Data Engineer • Coding • medium

Given an array of strings, write a Python function to group anagrams together.

#Python #Hash Maps #Strings #Sorting

Practice

Data Engineer • Coding • medium

Write a SQL query to calculate the cumulative sum of sales per region, ordered by date.

#Window Functions #SUM() OVER #Aggregations

Practice

Data Engineer • Coding • easy

Write a Python program to find the missing number in an array containing integers from 1 to N.

#Python #Math #Arrays

Practice

Data Engineer • Coding • medium

Write a PySpark script to read a CSV, drop rows with nulls in a specific column, group by another column, and write the output as Parquet.

#PySpark #DataFrame API #Data Cleaning

Practice

Data Engineer • Coding • medium

Write a SQL query to find the top 3 selling products in each category.

#Window Functions #RANK() #PARTITION BY

Practice

Data Engineer • System Design • hard

Design a batch data pipeline to process 10TB of daily transaction logs, ensuring idempotency and fault tolerance.

#Batch Processing #Idempotency #Fault Tolerance #Data Lakehouse

Practice

Data Engineer • System Design • hard

Design a data quality framework for a newly built data lakehouse. What checks would you implement?

#Data Quality #Data Governance #Lakehouse

Practice

Data Engineer • System Design • medium

Design an ETL pipeline to migrate on-premise SQL Server data to Azure Synapse Analytics for a retail client.

#Azure Data Factory #Azure Synapse #Data Migration #ETL

Practice

Data Engineer • System Design • hard

Design a real-time streaming pipeline to process clickstream data and generate hourly aggregations.

#Kafka #Spark Structured Streaming #Real-time Processing #Cloud Architecture

Practice

Data Engineer • Technical • medium

How do you pass data between different tasks in an Apache Airflow DAG?

#Airflow #Orchestration #XComs

Practice

Data Engineer • Technical • medium

What are Delta Lake's ACID properties? How does it handle concurrent writes?

#Databricks #Delta Lake #ACID #Concurrency

Practice

Data Engineer • Technical • medium

Explain the differences between Parquet, ORC, and Avro file formats. When would you choose Parquet over Avro?

#File Formats #Storage Optimization #Parquet #Avro

Practice

Data Engineer • Technical • easy

What is the difference between cache() and persist() in PySpark?

#PySpark #Memory Management #Caching

Practice

Data Engineer • Technical • hard

How do you ensure exactly-once processing semantics in an Apache Kafka streaming application?

#Kafka #Streaming #Exactly-once Semantics

Practice

Data Engineer • Technical • medium

Explain the architecture of Snowflake. How does it separate storage and compute?

#Snowflake #Cloud Data Warehouse #Architecture

Practice

Data Engineer • Technical • medium

How do you implement incremental data loading in Azure Data Factory (ADF)?

#Azure Data Factory #ETL #Incremental Load #Watermarking

Practice

Data Engineer • Technical • hard

How do you handle data skewness in a PySpark join operation?

#PySpark #Performance Tuning #Data Skewness #Salting

Practice

Data Engineer • Technical • hard

What is the Catalyst Optimizer in Spark? Explain its phases.

#Spark Internals #Catalyst Optimizer #Query Plans

Practice

Data Engineer • Technical • medium

Compare AWS Glue and Amazon EMR. When would you recommend one over the other to a client?

#AWS #Glue #EMR #Serverless

Practice

Data Engineer • Technical • medium

What are Broadcast Variables and Accumulators in Spark? Give use cases for each.

#PySpark #Shared Variables #Optimization

Practice

Data Engineer • Technical • medium

What is a Slowly Changing Dimension (SCD) Type 2? How would you implement it using PySpark?

#Data Warehousing #SCD #PySpark #ETL

Practice

Data Engineer • Technical • medium

Explain the internal execution hierarchy of a Spark application.

#Spark Architecture #Jobs #Stages #Tasks

Practice

Data Engineer • Technical • hard

How do you handle Out of Memory (OOM) errors in a PySpark application?

#PySpark #Troubleshooting #Memory Management

Practice

Data Engineer • Technical • easy

What is the difference between Star Schema and Snowflake Schema? Which one performs better in a modern cloud data warehouse?

#Data Warehousing #Star Schema #Snowflake Schema #Normalization

Practice

Data Engineer • Technical • medium

What is a Factless Fact table? Provide a real-world example of when you would use one.

#Data Warehousing #Fact Tables #Dimensional Modeling

Practice

Data Engineer • Technical • easy

Explain the difference between repartition() and coalesce() in PySpark. When would you use one over the other?

#PySpark #Data Partitioning #Shuffle

Practice

Data Engineer • Technical • medium

Explain Time Travel and Fail-safe features in Snowflake. How do they differ?

#Snowflake #Data Recovery #Architecture

Practice

Data Scientist • Behavioral • medium

Infosys often works with legacy systems. How would you approach extracting, cleaning, and modeling data from an outdated, poorly documented mainframe system?

#Legacy Systems #Data Cleaning #Adaptability #Consulting

Practice

Data Scientist • Behavioral • medium

A client wants to use an expensive GenAI solution to solve a business problem, but you realize a simple rule-based system or basic regression would be more effective and cheaper. How do you convince them?

#Consulting #Integrity #Communication #Cost-Benefit Analysis

Practice

Data Scientist • Behavioral • medium

Tell me about a time you had to push back on a client's unrealistic expectations regarding a machine learning model's accuracy.

#Stakeholder Management #Communication #Expectation Setting

Practice

Data Scientist • Behavioral • easy

Can you explain p-value and confidence intervals to a non-technical business stakeholder?

#Statistics #Stakeholder Management #Hypothesis Testing

Practice

Data Scientist • Behavioral • medium

Describe a situation where your model performed well in training but failed in production. How did you troubleshoot and fix it?

#Debugging #Production Issues #Overfitting #Data Leakage

Practice

Data Scientist • Behavioral • easy

Tell me about a time you had to learn a completely new technology stack or framework within a few weeks to deliver a client project.

#Adaptability #Continuous Learning #Agile

Practice

Data Scientist • Coding • medium

Write a SQL query to find the top 3 products by revenue in each region. The table contains product_id, region, and revenue.

#Window Functions #RANK() #DENSE_RANK() #Aggregation

Practice

Data Scientist • Coding • easy

Write a Python function using Pandas to find the second highest salary from an employee dataset, handling cases where multiple employees might have the same salary.

#Python #Pandas #Data Cleaning

Practice

Data Scientist • Coding • medium

Given a list of unstructured client transaction strings, write a Python function using regex to extract the transaction ID, date, and amount, and return them as a structured dictionary.

#Python #Regex #String Parsing

Practice

Data Scientist • Coding • hard

Given a table of user logins (user_id, login_date), write a SQL query to find users who logged in on 3 consecutive days.

#Self Joins #Window Functions #Date/Time Functions

Practice

Data Scientist • Coding • medium

Write a SQL query to calculate the month-over-month growth rate of active users from a daily activity log.

#Window Functions #CTEs #Aggregation

Practice

Data Scientist • Coding • easy

Write a Python script to perform a cross-validation on a dataset using Scikit-Learn, and explain why cross-validation is preferred over a simple train-test split.

#Python #Scikit-Learn #Cross-Validation

Practice

Data Scientist • System Design • hard

Design a recommendation system for an e-commerce client to suggest products based on user browsing history and past purchases.

#Collaborative Filtering #Content-Based Filtering #Matrix Factorization

Practice

Data Scientist • System Design • medium

How would you design an NLP pipeline to automatically categorize incoming IT support tickets into different resolution queues?

#Text Classification #TF-IDF #Transformers #Pipeline Design

Practice

Data Scientist • System Design • hard

A client wants to implement a Retrieval-Augmented Generation (RAG) system for their internal HR documents. Walk me through the architecture.

#RAG #LLMs #Vector Databases #Embeddings

Practice

Data Scientist • System Design • hard

A retail client wants to forecast inventory demand across 500 stores. How do you approach building a scalable time-series forecasting model?

#ARIMA #Prophet #Forecasting #Scalability

Practice

Data Scientist • System Design • hard

Design a system to predict equipment failure in a manufacturing plant using IoT sensor data. How do you handle the high-frequency streaming data?

#IoT #Streaming Data #Predictive Maintenance #Kafka

Practice

Data Scientist • Technical • medium

Explain the concept of Continuous Integration and Continuous Deployment (CI/CD) specifically in the context of Machine Learning (CT/CD).

#CI/CD #Automation #ML Pipelines #Continuous Training

Practice

Data Scientist • Technical • medium

How do you ensure data privacy and compliance, such as GDPR, when building predictive models using sensitive customer data?

#Data Privacy #GDPR #Anonymization #PII

Practice

Data Scientist • Technical • hard

Explain the architecture of a Transformer model. Why has it largely replaced RNNs and LSTMs in modern NLP tasks?

#Transformers #Attention Mechanism #NLP

Practice

Data Scientist • Technical • hard

How do you fine-tune an open-source LLM like Llama-3 for a specific enterprise use case while minimizing compute costs?

#LoRA #PEFT #Fine-tuning #Quantization

Practice

Data Scientist • Technical • medium

What are word embeddings? Compare traditional embeddings like Word2Vec with contextual embeddings like BERT.

#Embeddings #Word2Vec #BERT

Practice

Data Scientist • Technical • medium

How do you handle vanishing and exploding gradients in deep neural networks?

#Neural Networks #Optimization #Activation Functions

Practice

Data Scientist • Technical • easy

Explain the difference between a Star schema and a Snowflake schema in data warehousing.

#Data Modeling #Warehousing #Schema Design

Practice

Data Scientist • Technical • easy

What is the ROC curve and AUC? How would you explain an AUC of 0.5 to a project manager?

#Evaluation Metrics #ROC-AUC #Classification

Practice

Data Scientist • Technical • medium

Walk me through how you would deploy a Scikit-learn model as a REST API using FastAPI and Dockerize it for deployment on Azure.

#Model Deployment #FastAPI #Docker #Azure

Practice

Data Scientist • Technical • medium

How would you handle a dataset with 50 million rows in Python if it exceeds your available RAM during a client engagement?

#Memory Management #Dask #Chunking #PySpark

Practice

Data Scientist • Technical • medium

How do you optimize a slow-running SQL query that joins multiple large tables in a client's database?

#Query Optimization #Indexing #Execution Plan

Practice

Data Scientist • Technical • medium

Explain the difference between Random Forest and Gradient Boosting. Which one would you prefer for predicting client churn for a telecom client and why?

#Ensemble Methods #Bagging #Boosting #Classification

Practice

Data Scientist • Technical • medium

How do you handle highly imbalanced datasets in a fraud detection model for a banking client? What metrics would you use?

#Imbalanced Data #SMOTE #Precision-Recall #F1-Score

Practice

Data Scientist • Technical • medium

What is the curse of dimensionality, and how do you address it when working with high-dimensional enterprise data?

#PCA #Feature Selection #Dimensionality Reduction

Practice

Data Scientist • Technical • hard

Explain the mathematical intuition behind Support Vector Machines (SVM). What is the kernel trick and when do you use it?

#SVM #Mathematics #Kernels

Practice

Data Scientist • Technical • medium

Explain L1 and L2 regularization. When would you use Lasso over Ridge regression in a predictive maintenance model?

#Regularization #Regression #Feature Selection

Practice

Data Scientist • Technical • hard

How do you detect and handle data drift in a machine learning model deployed in production for a financial client?

#Data Drift #Model Monitoring #Evidently AI

Practice

Data Scientist • Technical • medium

What is the difference between K-Means and Hierarchical clustering? How do you determine the optimal number of clusters?

#Clustering #Unsupervised Learning #Elbow Method #Silhouette Score

Practice

Machine Learning Engineer • Behavioral • medium

Tell me about a time you had to explain a complex machine learning model to a non-technical client stakeholder. How did you ensure they understood?

#Client Interaction #Soft Skills

Practice

Machine Learning Engineer • Behavioral • hard

Describe a situation where your machine learning model performed exceptionally well in training but failed or underperformed in production. How did you troubleshoot and fix it?

#Debugging #Experience

Practice

Machine Learning Engineer • Behavioral • easy

Working at Infosys often means handling multiple client deliverables with tight deadlines. How do you prioritize your ML development tasks?

#Agile #Prioritization

Practice

Machine Learning Engineer • Behavioral • medium

Tell me about a time you disagreed with a senior engineer or a client regarding the choice of an ML algorithm or architecture. How did you resolve it?

#Teamwork #Leadership

Practice

Machine Learning Engineer • Behavioral • easy

The AI landscape, especially GenAI, is changing rapidly. How do you stay updated with the latest tools, frameworks, and research papers?

#Self-Improvement #AI Trends

Practice

Machine Learning Engineer • Behavioral • medium

Describe a time when you had to work with messy, unstructured, or incomplete data provided by a client. How did you approach the data cleaning and structuring process?

#Data Engineering #Client Interaction

Practice

Machine Learning Engineer • Coding • medium

Write a SQL query to find the nth highest salary from an Employee table. How would you handle ties?

#SQL #Window Functions

Practice

Machine Learning Engineer • Coding • medium

Find the length of the longest substring without repeating characters in a given string.

#Strings #Sliding Window

Practice

Machine Learning Engineer • Coding • medium

Write a Python function to calculate the TF-IDF scores for a given corpus of text documents from scratch, without using scikit-learn.

#Python #NLP #Math

Practice

Machine Learning Engineer • Coding • hard

Implement the K-Means clustering algorithm from scratch in Python using NumPy.

#Python #NumPy #Algorithms

Practice

Machine Learning Engineer • Coding • easy

Write a Python script using Pandas to handle missing values in a dataset containing both numerical and categorical columns, applying mean imputation for numerical and mode for categorical.

#Python #Pandas #Data Cleaning

Practice

Machine Learning Engineer • Coding • easy

Given an array of integers and an integer target, return indices of the two numbers such that they add up to target. Can you do it in O(n) time?

#Arrays #Hash Map

Practice

Machine Learning Engineer • Coding • medium

Write a SQL query using window functions to calculate the 7-day rolling average of transaction volumes for a banking client.

#SQL #Time Series #Window Functions

Practice

Machine Learning Engineer • Coding • medium

Given a list of intervals representing client server downtimes, merge all overlapping intervals.

#Arrays #Sorting

Practice

Machine Learning Engineer • System Design • hard

How would you design a real-time credit card fraud detection system capable of processing thousands of transactions per second?

#Real-time Processing #Scalability #Machine Learning

Practice

Machine Learning Engineer • System Design • hard

Design a predictive maintenance system for a manufacturing client's IoT sensor data to predict machine failures before they happen.

#IoT #Time Series #Architecture

Practice

Machine Learning Engineer • System Design • hard

Design a scalable recommendation engine for an e-commerce client. How do you handle the cold start problem for new users and new items?

#Recommender Systems #Architecture

Practice

Machine Learning Engineer • System Design • medium

Design an MLOps pipeline for the continuous training and deployment of an NLP sentiment analysis model.

#MLOps #CI/CD #NLP

Practice

Machine Learning Engineer • System Design • medium

A client wants to automate invoice processing. Design a document extraction system using OCR and Large Language Models.

#Computer Vision #LLMs #Architecture

Practice

Machine Learning Engineer • System Design • hard

How do you serve a PyTorch model in production to handle 10,000 requests per minute efficiently?

#Model Serving #Scalability

Practice

Machine Learning Engineer • System Design • hard

Design a personalized, secure chatbot for a banking client using Generative AI. How do you ensure it doesn't hallucinate sensitive financial advice?

#Generative AI #Security #Architecture

Practice

Machine Learning Engineer • Technical • medium

What are the vanishing and exploding gradient problems in deep neural networks, and how do LSTMs or ResNets solve them?

#Neural Networks #RNN #CNN

Practice

Machine Learning Engineer • Technical • medium

What is the difference between L1 (Lasso) and L2 (Ridge) regularization? When would you choose one over the other in a consulting project?

#Regularization #Linear Models

Practice

Machine Learning Engineer • Technical • hard

Explain the Self-Attention mechanism in Transformer models. Why is it more efficient than RNNs for long sequences?

#NLP #Transformers #LLMs

Practice

Machine Learning Engineer • Technical • medium

In a recent fraud detection project for a financial client, the dataset had a 99:1 class imbalance. How would you handle this highly imbalanced dataset?

#Imbalanced Data #Classification

Practice

Machine Learning Engineer • Technical • medium

Explain the bias-variance tradeoff. How do Random Forest and Gradient Boosting algorithms handle this tradeoff differently?

#Ensemble Methods #Model Evaluation

Practice

Machine Learning Engineer • Technical • hard

Explain how XGBoost works under the hood. What makes it faster and more accurate than traditional Gradient Boosting?

#Ensemble Methods #XGBoost

Practice

Machine Learning Engineer • Technical • medium

Explain the mathematical intuition behind Principal Component Analysis (PCA). How do you decide the number of principal components to keep?

#Dimensionality Reduction #Math

Practice

Machine Learning Engineer • Technical • easy

What are the core assumptions of Linear Regression? How do you check if they are violated?

#Linear Models #Statistics

Practice

Machine Learning Engineer • Technical • hard

How do you detect data drift and concept drift in a deployed machine learning model? How do you mitigate it?

#Model Monitoring #Data Drift

Practice

Machine Learning Engineer • Technical • medium

Explain the concept of Word2Vec. What is the difference between the Continuous Bag of Words (CBOW) and Skip-gram architectures?

#NLP #Embeddings

Practice

Machine Learning Engineer • Technical • medium

What is cross-validation, and why is standard k-fold cross-validation inappropriate for time-series data? What should you use instead?

#Time Series #Statistics

Practice

Machine Learning Engineer • Technical • medium

How do you evaluate a binary classification model? Explain the ROC-AUC curve and the Precision-Recall tradeoff.

#Metrics #Statistics

Practice

Machine Learning Engineer • Technical • medium

What is the difference between fine-tuning an LLM (like Llama 3) and using Prompt Engineering with RAG? When would you recommend each to a client?

#LLMs #Fine-tuning #Architecture

Practice

Machine Learning Engineer • Technical • medium

How does Retrieval-Augmented Generation (RAG) work? Walk me through how you would implement it for an enterprise knowledge base.

#LLMs #RAG #Vector Databases

Practice

Software Engineer • Behavioral • medium

Infosys deals with many enterprise clients. How would you handle a situation where the client drastically changes the requirements two days before a major sprint delivery?

#Client Management #Agile #Communication

Practice

Software Engineer • Behavioral • medium

Explain the most challenging bug you faced in your recent project. How did you debug and resolve it?

#Problem Solving #Debugging

Practice

Software Engineer • Behavioral • easy

Why do you want to join Infosys, and how do your career goals align with our core values?

#Company Knowledge #Motivation

Practice

Software Engineer • Behavioral • medium

Describe a time you disagreed with a senior team member or tech lead on a technical approach. How did you resolve it?

#Conflict Resolution #Teamwork

Practice

Software Engineer • Behavioral • medium

Infosys often requires engineers to adapt to new tech stacks. Tell me about a time you had to learn a new technology quickly to deliver a client project.

#Adaptability #Continuous Learning

Practice

Software Engineer • Coding • easy

Find the first non-repeating character in a string and return its index. If it doesn't exist, return -1.

#Strings #Hash Table

Practice

Software Engineer • Coding • easy

Find the second largest element in an unsorted integer array in O(n) time complexity.

#Arrays #Optimization

Practice

Software Engineer • Coding • medium

Find the length of the longest substring without repeating characters.

#Strings #Sliding Window #Hash Table

Practice

Software Engineer • Coding • easy

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.

#Arrays #Math #Bit Manipulation

Practice

Software Engineer • Coding • medium

Write a program to detect if there is a cycle in a singly linked list.

#Linked Lists #Two Pointers

Practice

Software Engineer • Coding • easy

Write a program to reverse a string in-place without using any built-in library functions.

#Strings #Two Pointers

Practice

Software Engineer • Coding • easy

What are the different types of JOINs in SQL? Write a query using a LEFT JOIN to find all customers who have not placed any orders.

#Joins #Data Retrieval

Practice

Software Engineer • Coding • medium

Write a SQL query to find the 3rd highest salary from an Employee table without using the LIMIT keyword.

#SQL Queries #Subqueries #Window Functions

Practice

Software Engineer • Coding • medium

Given a list of Employee objects, write a Java 8 Stream API snippet to filter employees older than 30 and collect their names into a List.

#Java 8 #Streams API #Lambdas

Practice

Software Engineer • Coding • medium

Write the code to implement a thread-safe Singleton design pattern in Java.

#Singleton #Multithreading

Practice

Software Engineer • Coding • easy

Given an array of integers and a target sum, return the indices of the two numbers that add up to the target.

#Arrays #Hash Table

Practice

Software Engineer • Coding • medium

Implement a Stack using two Queues.

#Stack #Queue #Data Structures

Practice

Software Engineer • Coding • easy

Write a function to check if a given string is a valid palindrome, ignoring non-alphanumeric characters and case.

#Strings #Two Pointers

Practice

Software Engineer • Coding • medium

Merge two sorted arrays into a single sorted array without using extra space.

#Arrays #Sorting

Practice

Software Engineer • System Design • medium

Explain how you would implement rate limiting for a public-facing API.

#API Gateway #Security #Algorithms

Practice

Software Engineer • System Design • medium

Design a URL shortening service like TinyURL. What database would you choose and why?

#Scalability #Database Design #Hashing

Practice

Software Engineer • System Design • hard

How would you design a scalable e-commerce checkout system that handles high traffic during a flash sale?

#Microservices #Message Queues #Concurrency

Practice

Software Engineer • Technical • easy

What are the differences between Checked and Unchecked exceptions in Java? When would you use each?

#Exception Handling

Practice

Software Engineer • Technical • easy

Explain the concepts of Compile-time and Run-time Polymorphism with real-world examples.

#Polymorphism #Method Overloading #Method Overriding

Practice

Software Engineer • Technical • medium

How does a HashMap work internally in Java? What happens when there is a collision?

#Collections Framework #Data Structures

Practice

Software Engineer • Technical • medium

Explain the difference between an Abstract Class and an Interface in Java. How has this changed since Java 8?

#OOPs #Java 8 Features

Practice

Software Engineer • Technical • medium

What is indexing in a database? How does it improve performance, and what are its drawbacks?

#Performance Tuning #Indexing

Practice

Software Engineer • Technical • medium

How do you handle exceptions globally in a Spring Boot application?

#Exception Handling #REST APIs

Practice

Software Engineer • Technical • easy

Explain the differences between TRUNCATE, DELETE, and DROP commands in SQL.

#DDL #DML

Practice

Software Engineer • Technical • medium

Explain how Garbage Collection works in Java. What are the different types of Garbage Collectors?

#JVM #Memory Management

Practice

Software Engineer • Technical • medium

Explain the concepts of Inversion of Control (IoC) and Dependency Injection (DI) in the context of the Spring Framework.

#Core Spring #Design Patterns

Practice

Software Engineer • Technical • medium

In a Microservices architecture, how do different services communicate with each other?

#Architecture #REST #Message Brokers

Practice

Software Engineer • Technical • easy

What is the exact difference between @Controller and @RestController in Spring Boot?

#Annotations #Spring MVC

Practice

Software Engineer • Technical • easy

What is the difference between the '==' operator and the '.equals()' method in Java?

#String Pool #Object Comparison

Practice

Software Engineer • Technical • easy

Explain the ACID properties in a Database Management System.

#Transactions #Database Theory

Practice

Infosys

The Interview Loop

Recruiter Screen (30 min)

Technical Loop (3-4 Rounds)

Interview Question Bank

Describe a time when you had to push back on a client's architectural request because it was not following cloud security best practices. How did you handle it?

Describe a situation where you had to work under a very tight deadline to deliver a cloud infrastructure project for a client. How did you prioritize your tasks?

Tell me about a time you had a disagreement with a senior engineer or architect regarding a technology choice. How was it resolved?

Tell me about a time you made a critical mistake in a production environment. What was the impact, and how did you recover and learn from it?

How do you keep yourself updated with the rapidly changing cloud technologies, and how do you apply this learning to client projects?

Write a SQL query to find the second highest salary from an 'Employee' table. (A common Infosys baseline data question).

Given an array of integers, write a function to move all zeros to the end of the array while maintaining the relative order of the non-zero elements. Do this in-place.

Write a function to find the first non-repeating character in a string. Return its index. If it does not exist, return -1.

Write a Python script using Boto3 to find and delete all unattached EBS volumes in a specific AWS region to help reduce client costs.

Write a Bash script that parses a web server access log file, counts the number of HTTP 500 errors, and outputs the top 5 IP addresses generating these errors.

Design a scalable log ingestion and analytics system for a microservices architecture generating 5TB of logs daily.

Design a secure and scalable architecture for a web application that requires processing large amounts of user-uploaded images asynchronously.

Design an API Gateway architecture for a client transitioning from a monolith to microservices. How do you handle authentication, rate limiting, and routing?

Explain the concept of RTO (Recovery Time Objective) and RPO (Recovery Point Objective). How do they influence your Disaster Recovery strategy in AWS?

Design a CI/CD pipeline for deploying a containerized application to an Azure Kubernetes Service (AKS) cluster.

Design a highly available, fault-tolerant architecture for a monolithic legacy application being migrated to the cloud using a 'Lift and Shift' approach.

What is a 'cold start' in serverless computing (e.g., AWS Lambda), and what strategies would you use to mitigate it for a latency-sensitive API?

What are Azure Resource Manager (ARM) templates, and how do they compare to Terraform? Why might a client choose one over the other?

How do you configure cross-account access in AWS so that a user in Account A can access an S3 bucket in Account B securely?

What is the difference between AWS CloudTrail and Amazon CloudWatch?

How do you handle secrets (like database passwords or API keys) in a cloud-native application to ensure they are not hardcoded in source code?

In Terraform, what is the difference between 'count' and 'for_each' when creating multiple instances of a resource?

Explain how you would design a secure AWS VPC architecture for a client's 3-tier web application, ensuring the database is completely isolated from the public internet.

What are the differences between Azure Blob Storage access tiers (Hot, Cool, Archive)? How do you automate the lifecycle management of these blobs?

What are Kubernetes Ingress controllers, and how do they differ from a LoadBalancer service type?

Compare AWS RDS Multi-AZ deployments with Read Replicas. When would you use each?

A Kubernetes pod is stuck in the 'CrashLoopBackOff' state. Walk me through your step-by-step troubleshooting process.

How do you optimize a Dockerfile to reduce the final image size and improve security for a Node.js microservice?

Explain the difference between IAM Policies, S3 Bucket Policies, and S3 ACLs. If an IAM policy allows access but a Bucket policy denies it, what is the effective permission?

How do you manage Terraform state files in a multi-developer team environment to prevent concurrent modification and state corruption?

What is the difference between an AWS Application Load Balancer (ALB) and a Network Load Balancer (NLB)? When would you choose one over the other for an enterprise migration?

In Jenkins, what is a Shared Library, and how does it help in managing CI/CD pipelines across multiple projects?

How do you ensure idempotency when writing Ansible playbooks for server configuration?

Explain how AWS Route 53 routing policies work. When would you use Latency-based routing versus Geolocation routing?

Explain the difference between a Security Group and a Network ACL in AWS.

How do you manage communication and ensure alignment when working in a distributed model with onshore and offshore teams?

Tell me about a time you had a disagreement with a client regarding a technical architecture choice. How did you resolve it?

Describe a situation where you had to quickly learn a new technology to deliver an urgent project requirement.

Write a Python script to read a large CSV file (10GB) that doesn't fit into memory, filter rows based on a condition, and write to a new file.

Write a SQL query to find the 3rd highest salary from an Employee table without using the LIMIT keyword.

Write a Python function to flatten a deeply nested JSON object/dictionary into a single-level dictionary.

Write a SQL query to delete duplicate rows from a table, keeping only the record with the lowest ID.

Write a SQL query to find employees who earn more than their direct managers.

Given an array of strings, write a Python function to group anagrams together.

Write a SQL query to calculate the cumulative sum of sales per region, ordered by date.

Write a Python program to find the missing number in an array containing integers from 1 to N.

Write a PySpark script to read a CSV, drop rows with nulls in a specific column, group by another column, and write the output as Parquet.

Write a SQL query to find the top 3 selling products in each category.

Design a batch data pipeline to process 10TB of daily transaction logs, ensuring idempotency and fault tolerance.

Design a data quality framework for a newly built data lakehouse. What checks would you implement?

Design an ETL pipeline to migrate on-premise SQL Server data to Azure Synapse Analytics for a retail client.

Design a real-time streaming pipeline to process clickstream data and generate hourly aggregations.

How do you pass data between different tasks in an Apache Airflow DAG?

What are Delta Lake's ACID properties? How does it handle concurrent writes?

Explain the differences between Parquet, ORC, and Avro file formats. When would you choose Parquet over Avro?

What is the difference between cache() and persist() in PySpark?

How do you ensure exactly-once processing semantics in an Apache Kafka streaming application?

Explain the architecture of Snowflake. How does it separate storage and compute?

How do you implement incremental data loading in Azure Data Factory (ADF)?

How do you handle data skewness in a PySpark join operation?

What is the Catalyst Optimizer in Spark? Explain its phases.

Compare AWS Glue and Amazon EMR. When would you recommend one over the other to a client?

What are Broadcast Variables and Accumulators in Spark? Give use cases for each.

What is a Slowly Changing Dimension (SCD) Type 2? How would you implement it using PySpark?

Explain the internal execution hierarchy of a Spark application.

How do you handle Out of Memory (OOM) errors in a PySpark application?

What is the difference between Star Schema and Snowflake Schema? Which one performs better in a modern cloud data warehouse?

What is a Factless Fact table? Provide a real-world example of when you would use one.

Explain the difference between repartition() and coalesce() in PySpark. When would you use one over the other?

Explain Time Travel and Fail-safe features in Snowflake. How do they differ?

Infosys often works with legacy systems. How would you approach extracting, cleaning, and modeling data from an outdated, poorly documented mainframe system?

A client wants to use an expensive GenAI solution to solve a business problem, but you realize a simple rule-based system or basic regression would be more effective and cheaper. How do you convince them?

Tell me about a time you had to push back on a client's unrealistic expectations regarding a machine learning model's accuracy.

Can you explain p-value and confidence intervals to a non-technical business stakeholder?

Describe a situation where your model performed well in training but failed in production. How did you troubleshoot and fix it?