Cognizant
American multinational information technology services and consulting company.
4 Rounds
~21 Days
Medium
The Interview Loop
Recruiter Screen (30 min)
Standard fit check, behavioral questions, and resume overview.
Technical Loop (3-4 Rounds)
Deep dive into domain knowledge, coding, and system design.
Interview Question Bank
Backend Engineer
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Behavioral
•
easy
How do you ensure code quality and maintainability within your development team?
#Best Practices
#Code Review
#CI/CD
Backend Engineer
•
Behavioral
•
medium
Describe a situation where you had to deliver a critical backend feature under a very tight deadline.
#Time Management
#Delivery
#Agile
Backend Engineer
•
Behavioral
•
medium
Tell me about a time you had a disagreement with a client regarding a technical requirement. How did you handle it?
#Communication
#Client Management
#Conflict Resolution
Backend Engineer
•
Behavioral
•
medium
Tell me about a time you found a critical bug in production. How did you handle the incident?
#Incident Management
#Debugging
#Accountability
Backend Engineer
•
Coding
•
medium
Implement a thread-safe Singleton class in Java.
#Multithreading
#Core Java
Backend Engineer
•
Coding
•
medium
Write a SQL query to find duplicate records in a table based on a specific column, and return the count of duplicates.
#Database
#Group By
#Having
Backend Engineer
•
Coding
•
medium
Write a Java program to find the first non-repeating character in a string using Java 8 Streams.
#Java 8
#Streams
#Strings
Backend Engineer
•
Coding
•
easy
Write a function to reverse a string in-place without using built-in functions like `StringBuilder.reverse()`.
#Strings
#Two Pointers
Backend Engineer
•
Coding
•
easy
Write a SQL query to find the second highest salary of an employee from an Employee table.
#Database
#Queries
Backend Engineer
•
Coding
•
medium
Given an array of strings, group the anagrams together.
#Strings
#HashMaps
Backend Engineer
•
Coding
•
easy
Write a program to merge two sorted linked lists into a single sorted linked list.
#Linked Lists
#Pointers
Backend 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. (Two Sum)
#Arrays
#HashMaps
Backend Engineer
•
System Design
•
hard
Design an API Rate Limiter. What algorithms would you use?
#Algorithms
#Scalability
#Caching
Backend Engineer
•
System Design
•
medium
How do you implement distributed tracing in a microservices architecture?
#Observability
#Spring Cloud Sleuth
#Zipkin
Backend Engineer
•
System Design
•
hard
Explain the Saga design pattern. How would you implement it for distributed transactions across microservices?
#Distributed Systems
#Transactions
#Event Driven
Backend Engineer
•
System Design
•
hard
Design a highly available healthcare patient record API. How do you handle data privacy and compliance (like HIPAA)?
#Security
#High Availability
#Healthcare
Backend Engineer
•
System Design
•
hard
Design the backend for an E-commerce inventory management system. How do you handle concurrent purchases of the same item?
#Concurrency
#Microservices
#Databases
Backend Engineer
•
System Design
•
hard
Design a microservices architecture for a banking fund transfer application. How do you ensure ACID properties across services?
#Microservices
#Banking
#ACID
Backend Engineer
•
Technical
•
medium
How do you secure a REST API? Explain the JWT authentication flow.
#Authentication
#REST
#JWT
Backend Engineer
•
Technical
•
medium
Explain the CAP theorem. How does it influence your choice of database for a microservice?
#Databases
#Architecture
Backend Engineer
•
Technical
•
medium
What are the key differences between REST and GraphQL? When would you choose GraphQL over REST?
#Web Services
#Architecture
Backend Engineer
•
Technical
•
medium
Explain the Bean lifecycle in the Spring framework.
#Framework
#IoC
Backend Engineer
•
Technical
•
medium
How do you resolve Circular Dependencies in a Spring Boot application?
#Dependency Injection
#Architecture
Backend Engineer
•
Technical
•
hard
What is the difference between `@Transactional(propagation = Propagation.REQUIRED)` and `REQUIRES_NEW`?
#Transactions
#Database
Backend Engineer
•
Technical
•
hard
Explain how Garbage Collection works in Java 11/17, specifically focusing on G1GC.
#JVM
#Memory Management
Backend Engineer
•
Technical
•
easy
How do you implement pagination and sorting in Spring Data JPA?
#JPA
#API Design
Backend Engineer
•
Technical
•
medium
How do you approach optimizing a slow-running query in PostgreSQL or Oracle?
#Performance Tuning
#Execution Plan
Backend Engineer
•
Technical
•
medium
What is the difference between Clustered and Non-Clustered Indexes in a relational database?
#Database
#Indexing
#Performance
Backend Engineer
•
Technical
•
hard
How do you handle message consumption failures in Kafka to ensure no data is lost?
#Kafka
#Resiliency
#DLQ
Backend Engineer
•
Technical
•
medium
Explain the role of an API Gateway in a microservices ecosystem. What cross-cutting concerns does it handle?
#Architecture
#Routing
#Security
Backend Engineer
•
Technical
•
medium
What is the N+1 select problem in Hibernate/JPA, and how do you resolve it?
#Hibernate
#JPA
#Performance Tuning
Backend Engineer
•
Technical
•
medium
How do you handle exceptions globally in a Spring Boot REST API?
#REST
#Error Handling
Backend Engineer
•
Technical
•
medium
How does Spring Boot auto-configuration work under the hood?
#Framework Internals
#Annotations
Backend Engineer
•
Technical
•
medium
Explain the internal working of ConcurrentHashMap in Java. How does it achieve thread safety without locking the entire map?
#Collections
#Multithreading
#Concurrency
Backend Engineer
•
Technical
•
easy
What is the difference between `@Component`, `@Service`, and `@Repository` in Spring?
#Annotations
#Architecture
Cloud Engineer
•
Behavioral
•
hard
Tell me about the most difficult production outage you had to troubleshoot. What was your approach to finding the root cause?
#Incident Management
#Problem Solving
#Observability
Cloud Engineer
•
Behavioral
•
easy
Cloud technologies change rapidly. Tell me about a new cloud service or DevOps tool you learned recently and how you applied it.
#Continuous Learning
#Adaptability
#Technology Trends
Cloud Engineer
•
Behavioral
•
medium
Tell me about a time you had to push back on a client's architectural request because it wasn't aligned with cloud best practices.
#Client Management
#Communication
#Best Practices
Cloud Engineer
•
Behavioral
•
medium
Describe a situation where you had to deliver a critical cloud infrastructure project under a very tight deadline. How did you prioritize?
#Time Management
#Prioritization
#Agile
Cloud Engineer
•
Behavioral
•
medium
Describe a time when you disagreed with a senior engineer or architect on a technical design. How did you resolve the disagreement?
#Conflict Resolution
#Communication
#Teamwork
Cloud Engineer
•
Coding
•
medium
Write a Python script using Boto3 to find and delete all unattached EBS volumes in a specific AWS region to save costs.
#Python
#Boto3
#AWS
#Automation
Cloud Engineer
•
Coding
•
medium
Write a Python script to check the expiration dates of SSL certificates across a list of domains and alert if they expire within 30 days.
#Python
#Security
#Automation
Cloud Engineer
•
Coding
•
medium
Write a bash script to parse an Nginx access log and find the top 10 IP addresses making requests.
#Bash
#Linux
#Log Parsing
Cloud Engineer
•
Coding
•
hard
Given an array of integers, write a function to find the first missing positive integer. It must run in O(n) time and use O(1) auxiliary space.
#Arrays
#Optimization
#Data Structures
Cloud Engineer
•
System Design
•
hard
How would you design a Disaster Recovery (DR) strategy with an RPO of 15 minutes and an RTO of 1 hour for a critical database?
#Disaster Recovery
#RPO/RTO
#Databases
Cloud Engineer
•
System Design
•
hard
Design a centralized logging and monitoring solution for a multi-cloud environment spanning AWS and Azure.
#Multi-Cloud
#Logging
#Monitoring
#System Design
Cloud Engineer
•
System Design
•
hard
A Cognizant enterprise client wants to migrate their on-premise monolithic application to AWS. Walk me through your migration strategy.
#Cloud Migration
#AWS
#Enterprise Architecture
Cloud Engineer
•
System Design
•
medium
Design a serverless architecture for an image processing application that creates thumbnails whenever a user uploads a photo.
#Serverless
#AWS
#Event-Driven
Cloud Engineer
•
System Design
•
medium
Design a highly available and fault-tolerant 3-tier web architecture on Azure.
#Azure
#High Availability
#System Design
Cloud Engineer
•
System Design
•
medium
How would you design a CI/CD pipeline for a containerized microservices application using Jenkins, Docker, and Kubernetes?
#CI/CD
#Jenkins
#Kubernetes
#Docker
Cloud Engineer
•
Technical
•
medium
Explain the concept of GitOps. How does a tool like ArgoCD implement this pattern?
#GitOps
#ArgoCD
#Kubernetes
Cloud Engineer
•
Technical
•
easy
Explain the AWS Shared Responsibility Model. What is the customer responsible for when using EC2 compared to Lambda?
#AWS
#Security
#Compliance
Cloud Engineer
•
Technical
•
easy
Explain the lifecycle of an S3 object and how you would use S3 Lifecycle policies to reduce storage costs over time.
#AWS
#S3
#Cost Optimization
Cloud Engineer
•
Technical
•
medium
What is the `terraform taint` command, and how has its functionality changed in newer versions of Terraform?
#Terraform
#State Management
Cloud Engineer
•
Technical
•
hard
How do you implement autoscaling in Kubernetes? Discuss the differences between HPA, VPA, and Cluster Autoscaler.
#Kubernetes
#Autoscaling
#Performance
Cloud Engineer
•
Technical
•
medium
What are Terraform modules, and how do you version control and distribute them across an enterprise?
#Terraform
#Reusability
#Version Control
Cloud Engineer
•
Technical
•
medium
How do you handle Terraform state files in a multi-developer environment to prevent conflicts and ensure security?
#Terraform
#State Management
#Collaboration
Cloud Engineer
•
Technical
•
hard
Walk me through exactly what happens in the control plane when you run `kubectl apply -f deployment.yaml`.
#Kubernetes
#Architecture
#API Server
Cloud Engineer
•
Technical
•
medium
Explain the difference between Azure Service Bus and Azure Event Grid. When would you use each in a microservices architecture?
#Azure
#Messaging
#Event-Driven Architecture
Cloud Engineer
•
Technical
•
easy
What is the difference between a Security Group and a Network ACL in AWS?
#AWS
#Security
#VPC
Cloud Engineer
•
Technical
•
medium
How do you manage secrets and sensitive data in a Kubernetes environment? Why are native K8s secrets not enough?
#Kubernetes
#Secrets Management
#DevSecOps
Cloud Engineer
•
Technical
•
medium
How do you optimize a Dockerfile to reduce the image size and improve security?
#Docker
#Optimization
#Security
Cloud Engineer
•
Technical
•
medium
Compare Google Kubernetes Engine (GKE) Autopilot with Standard GKE. When would you recommend Autopilot to a client?
#GCP
#Kubernetes
#Managed Services
Cloud Engineer
•
Technical
•
medium
When would you choose Amazon Aurora over Amazon RDS for PostgreSQL?
#AWS
#Databases
#Performance
Cloud Engineer
•
Technical
•
medium
Walk me through the process of setting up a blue-green deployment in Azure App Service.
#Azure
#Deployment Strategies
#CI/CD
Cloud Engineer
•
Technical
•
medium
Explain the difference between an Application Load Balancer (ALB) and a Network Load Balancer (NLB) in AWS. When would you choose one over the other?
#AWS
#Load Balancing
#OSI Model
Cloud Engineer
•
Technical
•
easy
Explain the difference between a ClusterIP, NodePort, and LoadBalancer service in Kubernetes.
#Kubernetes
#Networking
#Services
Cloud Engineer
•
Technical
•
hard
A client's AWS bill has spiked by 40% over the last month. How do you investigate and optimize their cloud costs?
#AWS
#Cost Optimization
#FinOps
Cloud Engineer
•
Technical
•
medium
How do you establish a secure, highly available connection between an on-premise data center and an AWS VPC?
#AWS
#Hybrid Cloud
#VPN
#Direct Connect
Cloud Engineer
•
Technical
•
medium
What are Azure Managed Identities, and how do they differ from Service Principals?
#Azure
#IAM
#Security
Data Engineer
•
Behavioral
•
hard
Tell me about a complex data pipeline you built from scratch. What were the biggest technical challenges and how did you overcome them?
#Project Experience
#Problem Solving
#End-to-End Delivery
Data Engineer
•
Behavioral
•
medium
Tell me about a time when a client changed the data requirements in the middle of a sprint. How did you handle the pipeline refactoring and communicate the impact?
#Agile
#Client Communication
#Adaptability
Data Engineer
•
Behavioral
•
medium
Have you ever disagreed with a Data Architect or Lead regarding a pipeline design? How did you handle the disagreement?
#Conflict Resolution
#Communication
#Teamwork
Data Engineer
•
Behavioral
•
medium
Describe a time you had to optimize cloud costs for a data engineering project at a client site.
#Cost Optimization
#Cloud
#Client Delivery
Data Engineer
•
Coding
•
medium
Write a Python generator function that reads a massive log file line by line and yields lines containing the word 'ERROR'. Why use a generator here?
#Generators
#Memory Management
#File I/O
Data Engineer
•
Coding
•
medium
Write a PySpark script to read a CSV file from S3, drop rows with null values in a specific column, group by another column to find the average, and write the output back to S3 as Parquet.
#DataFrames
#I/O
#Aggregations
Data Engineer
•
Coding
•
medium
Write a SQL query to find the cumulative sum of sales per day for the current month.
#Window Functions
#Aggregations
#Date Functions
Data Engineer
•
Coding
•
hard
Write a Python script to flatten a deeply nested JSON object representing a client's API response into a flat dictionary.
#Recursion
#JSON
#Data Parsing
Data Engineer
•
Coding
•
easy
Write a Python function to check if two strings are anagrams of each other. Optimize it for time complexity.
#Python
#Strings
#Hash Maps
Data Engineer
•
Coding
•
medium
Write a SQL query to find the top 3 highest earning employees in each department, handling ties appropriately.
#Window Functions
#DENSE_RANK
#PARTITION BY
Data Engineer
•
Coding
•
medium
Write a SQL query to delete duplicate rows from a table, keeping only the record with the lowest ID.
#Data Cleaning
#CTEs
#DELETE
Data Engineer
•
Coding
•
easy
Write a SQL query to find all employees who earn more than their direct managers. The table 'Employee' has columns: Id, Name, Salary, ManagerId.
#Self Join
#Filtering
Data Engineer
•
Coding
•
easy
Given a list of dictionaries representing employee data, write a Python script using list comprehensions to extract the names of employees who belong to the 'IT' department and have a salary > 80000.
#List Comprehensions
#Data Manipulation
Data Engineer
•
Coding
•
medium
Write a PySpark DataFrame query to pivot a table. You have columns: 'Store', 'Month', and 'Revenue'. Pivot the 'Month' column so each month is a separate column showing the revenue.
#Pivot
#Data Aggregation
Data Engineer
•
System Design
•
hard
Design a system to ingest and process daily healthcare claims data (HIPAA compliant). The data arrives as CSVs in an SFTP server.
#Healthcare
#Security
#ETL
#Cloud Architecture
Data Engineer
•
System Design
•
medium
Design a CI/CD pipeline for deploying Data Engineering assets (Airflow DAGs, Snowflake SQL scripts, PySpark code).
#CI/CD
#DevOps
#Git
#Jenkins/GitHub Actions
Data Engineer
•
System Design
•
hard
Design a batch ETL pipeline to migrate 500GB of daily transactional data from an on-premise Oracle database to Snowflake on AWS. What tools and architecture would you use?
#AWS
#Snowflake
#Data Migration
#ETL Architecture
Data Engineer
•
System Design
•
hard
Design a real-time streaming pipeline to process clickstream data from a retail client's website and update a live dashboard.
#Streaming
#Kafka
#Spark Streaming
#Real-time Analytics
Data Engineer
•
Technical
•
medium
What is the difference between repartition() and coalesce() in PySpark? When would you use one over the other?
#Partitioning
#Performance Tuning
Data Engineer
•
Technical
•
medium
Explain the architecture of Snowflake. How does its separation of compute and storage benefit a multi-tenant consulting project?
#Snowflake
#Architecture
#Virtual Warehouses
Data Engineer
•
Technical
•
hard
You have a PySpark job failing with an OutOfMemory (OOM) error on the executor side. What are the potential causes and how do you troubleshoot it?
#Troubleshooting
#Memory Management
#OOM
Data Engineer
•
Technical
•
medium
How do you implement Slowly Changing Dimension (SCD) Type 2 in a data warehouse? Describe the necessary columns and the update logic.
#SCD
#Data Warehousing
#ETL
Data Engineer
•
Technical
•
easy
Explain the difference between ROW_NUMBER(), RANK(), and DENSE_RANK(). In what client reporting scenario would you choose DENSE_RANK over RANK?
#Window Functions
#Data Analysis
Data Engineer
•
Technical
•
hard
How do you handle data skewness in PySpark? Walk me through the exact steps you would take if a join operation is taking too long due to a skewed key.
#Performance Tuning
#Data Skew
#Salting
#Broadcast Join
Data Engineer
•
Technical
•
easy
What is the difference between a narrow and wide transformation in Spark? Give examples of each.
#Spark Architecture
#Transformations
#Shuffling
Data Engineer
•
Technical
•
medium
What is the difference between Star Schema and Snowflake Schema? Which one is preferred in modern columnar data warehouses and why?
#Star Schema
#Snowflake Schema
#Dimensional Modeling
Data Engineer
•
Technical
•
hard
Explain the CAP theorem. How does it apply to choosing a NoSQL database like Cassandra vs MongoDB for a specific use case?
#CAP Theorem
#NoSQL
#System Architecture
Data Engineer
•
Technical
•
medium
What are User Defined Functions (UDFs) in PySpark? Why are Python UDFs generally discouraged, and what is the alternative?
#UDFs
#Performance Tuning
#Pandas UDFs
Data Engineer
•
Technical
•
medium
In AWS, what is the difference between Amazon Redshift and Amazon Athena? When would you use Athena for a client project?
#AWS
#Redshift
#Athena
#Serverless
Data Engineer
•
Technical
•
medium
Explain the concept of Predicate Pushdown in Spark and Snowflake. How does it improve query performance?
#Predicate Pushdown
#Query Optimization
Data Engineer
•
Technical
•
easy
What is the difference between a Left Join and an Inner Join? What happens to the result set if the right table has multiple matching rows for a single row in the left table?
#Joins
#Data Duplication
Data Engineer
•
Technical
•
medium
How does Spark handle fault tolerance? Explain the role of the DAG and RDD lineage.
#Fault Tolerance
#Lineage
#DAG
Data Engineer
•
Technical
•
easy
What are Parquet files? Why are they preferred over CSV or JSON in Big Data processing?
#File Formats
#Parquet
#Columnar Storage
Data Engineer
•
Technical
•
medium
Describe your experience with Apache Airflow. How do you pass data between tasks in an Airflow DAG?
#Airflow
#XComs
#DAGs
Data Engineer
•
Technical
•
medium
Explain the concept of a Data Mesh. How does it differ from a traditional centralized Data Lake architecture?
#Data Mesh
#Data Lake
#Decentralization
Data Scientist
•
Behavioral
•
medium
At Cognizant, we often inherit messy data from clients. Tell me about a time you realized the client's data quality was too poor to build the requested model. How did you handle it?
#Data Quality
#Client Management
#Problem Solving
Data Scientist
•
Behavioral
•
medium
Tell me about a time you had to explain a complex machine learning concept (like neural networks or ensemble methods) to a non-technical client stakeholder.
#Communication
#Stakeholder Management
Data Scientist
•
Behavioral
•
medium
Describe a project where the client's business requirements changed drastically halfway through the modeling phase. How did you adapt?
#Agile
#Adaptability
#Project Management
Data Scientist
•
Behavioral
•
medium
Tell me about a time you disagreed with a senior data scientist or technical architect on a modeling approach. How did you resolve it?
#Conflict Resolution
#Teamwork
#Leadership
Data Scientist
•
Behavioral
•
easy
Working in an IT services firm often means juggling multiple client deliverables. How do you prioritize your tasks when everything seems urgent?
#Time Management
#Prioritization
Data Scientist
•
Coding
•
medium
Given a string, write a Python function to find the longest palindromic substring.
#String Manipulation
#Dynamic Programming
#Two Pointers
Data Scientist
•
Coding
•
medium
Write a Python function using Pandas to merge two large datasets (10M+ rows) efficiently. What potential memory issues might you face and how do you resolve them?
#Pandas
#Memory Management
#Data Merging
Data Scientist
•
Coding
•
easy
Write a Python script from scratch to detect anomalies in a list of daily transaction volumes using the Z-score method.
#Statistics
#Anomaly Detection
#Arrays
Data Scientist
•
Coding
•
medium
Given a table of customer transactions, write a query to identify 'churned' customers, defined as those who made a purchase in the last 6 months but not in the last 30 days.
#Filtering
#Date Functions
#Conditional Logic
Data Scientist
•
Coding
•
medium
For a retail client, we need to calculate the 7-day rolling average of daily sales. Write the SQL query to achieve this.
#Window Functions
#Time Series
#Moving Averages
Data Scientist
•
Coding
•
medium
Write a SQL query to find the second highest salary within each department from an Employee table. How would you handle ties?
#Window Functions
#DENSE_RANK
#Data Aggregation
Data Scientist
•
Coding
•
hard
Implement a basic TF-IDF vectorizer function in Python without using scikit-learn. It should take a list of strings and return a dictionary of TF-IDF scores.
#NLP
#Text Processing
#Math
Data Scientist
•
System Design
•
medium
A model deployed for a retail client 6 months ago is showing degraded performance. What are the types of model drift, and how do you detect them?
#Model Monitoring
#Data Drift
#Concept Drift
Data Scientist
•
System Design
•
medium
Walk me through the process of taking a trained scikit-learn model and deploying it as a REST API in a production environment.
#Deployment
#FastAPI/Flask
#Docker
Data Scientist
•
System Design
•
hard
A healthcare client wants a chatbot to query their internal medical guidelines. Design a Retrieval-Augmented Generation (RAG) pipeline for this.
#RAG
#LLMs
#Vector Databases
#NLP
Data Scientist
•
System Design
•
hard
Design the architecture for a real-time credit card fraud detection system that must return a prediction in under 50 milliseconds.
#Real-time Processing
#Latency
#Streaming
Data Scientist
•
System Design
•
hard
Your batch inference pipeline needs to process 10 million records nightly. How do you design this to be scalable and fault-tolerant?
#Batch Processing
#Distributed Computing
#Spark
Data Scientist
•
System Design
•
hard
Design a personalized product recommendation system for a large e-commerce client. Walk me through the data, algorithms, and serving architecture.
#Recommendation Systems
#Collaborative Filtering
#Architecture
Data Scientist
•
Technical
•
medium
How do you evaluate the performance of a Generative AI model tasked with summarizing client meeting transcripts?
#Evaluation Metrics
#NLP
#Summarization
Data Scientist
•
Technical
•
medium
How do traditional NLP models (like Word2Vec) handle Out-Of-Vocabulary (OOV) words, and how do modern LLMs handle them differently?
#Tokenization
#Embeddings
#Word2Vec
Data Scientist
•
Technical
•
medium
Describe your experience using cloud platforms (AWS SageMaker, Azure ML, or GCP Vertex AI) for end-to-end model training and deployment.
#Cloud Computing
#AWS
#Azure
#GCP
Data Scientist
•
Technical
•
hard
You need to adapt an open-source LLM (e.g., Llama 3) to understand specific legal jargon for a client. What fine-tuning approach would you use given limited compute resources?
#Fine-tuning
#PEFT
#LoRA
#LLMs
Data Scientist
•
Technical
•
easy
Explain the difference between RANK, DENSE_RANK, and ROW_NUMBER. Give a business scenario where you would use each.
#Window Functions
#Ranking
Data Scientist
•
Technical
•
medium
You are working on a predictive maintenance model for a manufacturing client. The sensor data has 30% missing values. How do you handle this?
#Imputation
#Missing Data
#Feature Engineering
Data Scientist
•
Technical
•
medium
We are building a credit card fraud detection model for a BFSI client. The positive class (fraud) is only 0.1% of the data. How do you approach this problem?
#Imbalanced Data
#SMOTE
#Evaluation Metrics
Data Scientist
•
Technical
•
medium
Compare Random Forest and Gradient Boosting. In what scenarios would you choose one over the other?
#Ensemble Methods
#Bagging
#Boosting
Data Scientist
•
Technical
•
hard
Explain how L1 (Lasso) and L2 (Ridge) regularization work. Why does L1 lead to sparsity?
#Regularization
#Feature Selection
#Mathematics
Data Scientist
•
Technical
•
medium
You have segmented a client's customer base using K-Means clustering, but you have no ground truth labels. How do you evaluate the quality of your clusters?
#Unsupervised Learning
#Clustering
#Metrics
Data Scientist
•
Technical
•
hard
Walk me through the mathematical formulation of Logistic Regression. How are the coefficients updated during training?
#Mathematics
#Optimization
#Gradient Descent
Data Scientist
•
Technical
•
medium
What is data leakage in machine learning? Give an example of how it might happen during feature engineering and how to prevent it.
#Model Validation
#Feature Engineering
#Best Practices
Data Scientist
•
Technical
•
medium
How do you detect and deal with multicollinearity in a multiple linear regression model?
#Statistics
#Regression
#Feature Selection
Data Scientist
•
Technical
•
medium
A retail client wants to know *why* a specific customer was denied a premium loyalty upgrade by your model. Explain how you would use SHAP values to answer them.
#SHAP
#Model Interpretability
#Client Communication
Data Scientist
•
Technical
•
hard
Explain the self-attention mechanism in Transformer models. Why is it more effective than RNNs for long text sequences?
#Transformers
#NLP
#Attention
Data Scientist
•
Technical
•
medium
You have a slow-running SQL query with multiple JOINs on large tables for a healthcare client. Walk me through your step-by-step approach to optimize it.
#Query Execution Plan
#Indexing
#Partitioning
Data Scientist
•
Technical
•
easy
Explain the Bias-Variance tradeoff. How do you know if your model is suffering from high bias or high variance?
#Model Evaluation
#Overfitting
#Underfitting
Frontend Engineer
•
Behavioral
•
hard
Describe a time you inherited a poorly written legacy codebase at a client site. How did you approach refactoring it?
#Refactoring
#Legacy Code
#Strategy
Frontend Engineer
•
Behavioral
•
easy
Why do you want to work at Cognizant, and how do you adapt to shifting project domains (e.g., moving from a Healthcare client to a Banking client)?
#Adaptability
#Consulting Mindset
#Motivation
Frontend Engineer
•
Behavioral
•
medium
Explain a complex technical concept (e.g., Redux, Virtual DOM) to a non-technical project manager or client stakeholder.
#Communication
#Stakeholder Management
Frontend Engineer
•
Behavioral
•
medium
Tell me about a time you had a disagreement with a QA engineer regarding a reported bug.
#Collaboration
#Conflict Resolution
#Quality Assurance
Frontend Engineer
•
Behavioral
•
medium
Tell me about a time you had to push back on a client's technical requirement because it wasn't feasible or optimal.
#Communication
#Consulting
#Conflict Resolution
Frontend Engineer
•
Behavioral
•
easy
How do you approach mentoring junior developers or new team members on a project?
#Mentorship
#Teamwork
#Code Reviews
Frontend Engineer
•
Behavioral
•
medium
How do you handle a situation in an Agile sprint where the backend API is delayed, but you are expected to deliver the frontend UI?
#Agile
#Problem Solving
#Mocking
Frontend Engineer
•
Coding
•
medium
Write a polyfill for Promise.all().
#Promises
#Asynchronous JavaScript
#Polyfills
Frontend Engineer
•
Coding
•
medium
Implement a custom Array.prototype.reduce() function from scratch.
#Array Methods
#Functional Programming
#Polyfills
Frontend Engineer
•
Coding
•
medium
Implement a debounce function and explain how it differs from a throttle function.
#Performance
#Timers
#Higher-Order Functions
Frontend Engineer
•
Coding
•
medium
Write a function to deep clone a nested JavaScript object without using JSON.parse(JSON.stringify()).
#Recursion
#Objects
#Data Structures
Frontend Engineer
•
Coding
•
medium
Write a custom React hook called 'useFetch' that takes a URL and returns data, loading, and error states.
#Custom Hooks
#useEffect
#useState
#API Integration
Frontend Engineer
•
Coding
•
medium
Implement a paginated data table component in React that fetches data from a mock API.
#Component Design
#Pagination
#API Integration
Frontend Engineer
•
Coding
•
medium
Create a custom Angular directive that restricts an input field to only accept numeric values.
#Directives
#HostListener
#DOM Manipulation
Frontend Engineer
•
Coding
•
medium
Using CSS Grid or Flexbox, implement a 'Holy Grail' layout (Header, Footer, Left Sidebar, Right Sidebar, Main Content).
#CSS Grid
#Flexbox
#Layouts
Frontend Engineer
•
Coding
•
easy
Build a responsive navigation bar with a hamburger menu that toggles on mobile devices.
#Responsive Design
#Media Queries
#UI Components
Frontend Engineer
•
System Design
•
medium
Design the frontend architecture for an autocomplete/typeahead search widget.
#Component Architecture
#Performance
#State Management
Frontend Engineer
•
System Design
•
hard
Design an e-commerce checkout flow frontend that integrates with multiple third-party payment gateways.
#Architecture
#Security
#Forms
Frontend Engineer
•
System Design
•
hard
Design a real-time chat application frontend. Focus on state management, network protocols, and performance.
#WebSockets
#Real-time
#State Management
Frontend Engineer
•
Technical
•
medium
Given a code snippet with synchronous console.logs, setTimeouts, and Promises, what is the exact output order and why?
#Event Loop
#Microtasks
#Macrotasks
Frontend Engineer
•
Technical
•
easy
Explain the differences between call(), apply(), and bind() with examples.
#Context
#Functions
#this keyword
Frontend Engineer
•
Technical
•
easy
How do you handle prop drilling in a deeply nested component tree?
#Architecture
#State Management
#Component Composition
Frontend Engineer
•
Technical
•
medium
When should you use useMemo and useCallback? What are the performance trade-offs?
#Performance Optimization
#Hooks
#Memoization
Frontend Engineer
•
Technical
•
medium
How does React's Virtual DOM work, and what is the reconciliation process (Fiber)?
#Virtual DOM
#Reconciliation
#React Fiber
Frontend Engineer
•
Technical
•
easy
What is the difference between Event Bubbling and Event Capturing? How does Event Delegation work?
#DOM Manipulation
#Events
Frontend Engineer
•
Technical
•
easy
Explain CSS Specificity. How do you override a style safely without using !important?
#CSS Specificity
#Styling Architecture
Frontend Engineer
•
Technical
•
medium
Explain the Angular component lifecycle hooks in the order they execute.
#Lifecycle Hooks
#Components
Frontend Engineer
•
Technical
•
medium
Compare Redux Toolkit with the React Context API. When would you choose one over the other for an enterprise client?
#State Management
#Redux
#Context API
#Architecture
Frontend Engineer
•
Technical
•
hard
In Angular/RxJS, what is the difference between switchMap, mergeMap, concatMap, and exhaustMap?
#RxJS
#Observables
#Reactive Programming
Frontend Engineer
•
Technical
•
hard
Explain React Server Components (RSC) and how they differ from Client Components in Next.js.
#Next.js
#Server Components
#Rendering Strategies
Frontend Engineer
•
Technical
•
medium
Explain closures in JavaScript and provide a practical use case where you have used them in a recent project.
#Closures
#Scope
#Lexical Environment
Frontend Engineer
•
Technical
•
medium
How do you unit test a React component that makes an asynchronous API call using Jest and React Testing Library?
#Jest
#React Testing Library
#Mocking
Frontend Engineer
•
Technical
•
medium
What are Core Web Vitals? Explain LCP, FID/INP, and CLS.
#Core Web Vitals
#SEO
#User Experience
Frontend Engineer
•
Technical
•
hard
A client complains that their enterprise web application takes too long to load. How do you diagnose and optimize it?
#Web Performance
#Optimization
#Profiling
Frontend Engineer
•
Technical
•
medium
What are some key Web Accessibility (WCAG) best practices you follow when building UI components?
#a11y
#Semantic HTML
#ARIA
Machine Learning Engineer
•
Behavioral
•
medium
Tell me about a time you had to explain a complex technical concept or ML model to a non-technical client stakeholder.
#Communication
#Client Management
Machine Learning Engineer
•
Behavioral
•
medium
Working at a consultancy like Cognizant often means juggling multiple client deliverables. How do you prioritize your tasks?
#Prioritization
#Agile
#Time Management
Machine Learning Engineer
•
Behavioral
•
medium
How do you handle a situation where the client's data is of very poor quality, but they expect a high-performing predictive model?
#Stakeholder Management
#Problem Solving
Machine Learning Engineer
•
Behavioral
•
hard
A client mandates the use of a specific technology stack that you believe is suboptimal for their ML use case. How do you approach this?
#Consulting
#Negotiation
#Client Management
Machine Learning Engineer
•
Behavioral
•
easy
Describe a time you missed a project deadline. What happened, and how did you handle it with your team and the client?
#Accountability
#Time Management
Machine Learning Engineer
•
Behavioral
•
medium
Tell me about a time you disagreed with a senior engineer or architect on a technical approach. How did you resolve it?
#Conflict Resolution
#Teamwork
Machine Learning Engineer
•
Coding
•
easy
Write a SQL query to find the second highest salary from an Employee table. How would you modify this to find the Nth highest salary?
#SQL
#Subqueries
#Window Functions
Machine Learning Engineer
•
Coding
•
medium
Given two large Pandas DataFrames containing client transaction data, how would you efficiently merge them on a specific key while handling potential memory issues?
#Python
#Pandas
#Memory Management
Machine Learning Engineer
•
Coding
•
medium
Write a Python function to find the top K frequent elements in an array. Can you optimize it to run in O(N log K) time?
#Python
#Heaps
#Hash Maps
Machine Learning Engineer
•
Coding
•
medium
Implement a basic Linear Regression algorithm from scratch using only NumPy.
#Python
#NumPy
#Mathematics
#Gradient Descent
Machine Learning Engineer
•
Coding
•
medium
Write a SQL query to calculate a 7-day rolling average of daily sales for a retail client.
#SQL
#Window Functions
#Time Series Data
Machine Learning Engineer
•
Coding
•
easy
Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
#Python
#Stacks
#Strings
Machine Learning Engineer
•
Coding
•
medium
Write a Python script using PyTorch or TensorFlow to define a simple Convolutional Neural Network (CNN) for image classification.
#Python
#PyTorch
#TensorFlow
#CNNs
Machine Learning Engineer
•
System Design
•
hard
How do you optimize the inference speed of a Large Language Model (LLM) deployed in production?
#LLMs
#Optimization
#Inference
Machine Learning Engineer
•
System Design
•
hard
Design a scalable batch scoring pipeline that needs to process 100 million records every night.
#Batch Processing
#Big Data
#Spark
#Airflow
Machine Learning Engineer
•
System Design
•
medium
A client wants to build an internal chatbot to query their proprietary PDF documents. Would you recommend fine-tuning an LLM or using RAG (Retrieval-Augmented Generation)? Why?
#Generative AI
#LLMs
#RAG
#Architecture
Machine Learning Engineer
•
System Design
•
medium
How do you monitor a machine learning model in production? Specifically, how do you detect and handle concept drift?
#Model Monitoring
#Concept Drift
#MLOps
Machine Learning Engineer
•
System Design
•
hard
Design a personalized product recommendation system for a large e-commerce client. Walk me through the data, model choices, and serving architecture.
#Recommendation Systems
#Architecture
#Scalability
Machine Learning Engineer
•
Technical
•
medium
A client complains that your machine learning model is a 'black box'. How do you explain the model's predictions to non-technical stakeholders?
#Explainable AI
#SHAP
#LIME
Machine Learning Engineer
•
Technical
•
medium
Describe your experience with cloud ML platforms like AWS SageMaker, Azure ML, or GCP Vertex AI. How do you use them for model training and deployment?
#Cloud Computing
#AWS
#Azure
#GCP
Machine Learning Engineer
•
Technical
•
medium
Walk me through how you would containerize a trained Scikit-Learn model and deploy it as a REST API.
#Docker
#FastAPI
#Deployment
Machine Learning Engineer
•
Technical
•
medium
Compare Word2Vec and BERT embeddings. What are the fundamental differences in how they represent words?
#NLP
#Embeddings
#BERT
Machine Learning Engineer
•
Technical
•
hard
What are LLM hallucinations, and what specific techniques would you implement to mitigate them in a production enterprise application?
#Generative AI
#LLMs
#Prompt Engineering
Machine Learning Engineer
•
Technical
•
hard
How does Self-Attention work in a Transformer model?
#NLP
#Transformers
#Attention Mechanism
Machine Learning Engineer
•
Technical
•
medium
Explain the vanishing gradient problem in Deep Learning. How do modern architectures solve it?
#Neural Networks
#Activation Functions
#Backpropagation
Machine Learning Engineer
•
Technical
•
medium
What strategies do you use to handle missing data in a dataset provided by a client?
#Data Cleaning
#Imputation
Machine Learning Engineer
•
Technical
•
medium
You have a categorical feature with over 10,000 unique values (e.g., zip codes). How do you encode this feature for a tree-based model?
#Feature Engineering
#Categorical Encoding
Machine Learning Engineer
•
Technical
•
medium
How do you determine the optimal number of clusters (K) in a K-Means clustering algorithm?
#Unsupervised Learning
#Clustering
Machine Learning Engineer
•
Technical
•
easy
For a healthcare client predicting cancer from scans, which evaluation metric is more important: Precision or Recall? Why?
#Evaluation Metrics
#Domain Knowledge
Machine Learning Engineer
•
Technical
•
medium
What feature engineering techniques would you apply to a dataset containing user clickstream data to predict customer churn?
#Feature Engineering
#Time Series
#Domain Knowledge
Machine Learning Engineer
•
Technical
•
medium
Explain L1 (Lasso) and L2 (Ridge) regularization. Which one would you use if you wanted to perform feature selection?
#Regularization
#Feature Selection
#Mathematics
Machine Learning Engineer
•
Technical
•
medium
Explain the concept of Data Leakage in machine learning. Give an example of how it might happen during feature engineering.
#Data Leakage
#Model Evaluation
#Feature Engineering
Machine Learning Engineer
•
Technical
•
medium
What is the difference between Random Forest and Gradient Boosting? When would you choose one over the other for a client project?
#Ensemble Methods
#Bagging
#Boosting
Machine Learning Engineer
•
Technical
•
easy
Explain the Bias-Variance tradeoff. How does increasing the depth of a Decision Tree affect bias and variance?
#Model Evaluation
#Decision Trees
#Overfitting
Machine Learning Engineer
•
Technical
•
medium
We are building a fraud detection model for a banking client where the fraudulent transactions are less than 0.1% of the data. How do you handle this extreme class imbalance?
#Imbalanced Data
#SMOTE
#Class Weights
#Evaluation Metrics
Product Manager
•
Behavioral
•
medium
Describe a time when data contradicted your intuition about a product feature. What did you do?
#Analytics
#Humility
#Pivot
Product Manager
•
Behavioral
•
hard
Tell me about a time the project scope changed drastically halfway through the development cycle due to a change in client leadership.
#Scope Creep
#Change Management
#Client Relations
Product Manager
•
Behavioral
•
hard
Give an example of how you influenced a senior executive to change their mind about a product feature without having direct authority over them.
#Influence without Authority
#Executive Communication
#Data-Driven Decisions
Product Manager
•
Behavioral
•
easy
You have 10 features requested by the client, but capacity for only 3 in the next sprint. Walk me through your prioritization framework.
#Frameworks
#Sprint Planning
#Client Management
Product Manager
•
Behavioral
•
medium
Tell me about a time you disagreed with the lead engineer on the technical approach for a product. How was it resolved?
#Engineering Relations
#Collaboration
#Decision Making
Product Manager
•
Behavioral
•
medium
Tell me about a time you had to cut corners to meet a strict client deadline. How did you manage the resulting technical debt?
#Technical Debt
#Trade-offs
#Deadline Management
Product Manager
•
Behavioral
•
medium
Describe a situation where a digital transformation project was falling behind schedule. How did you handle it and communicate it to the client?
#Agile
#Risk Management
#Client Communication
Product Manager
•
Behavioral
•
medium
Tell me about a time you had to manage conflicting priorities between a Cognizant client's demands and your internal engineering team's capacity.
#Client Relations
#Prioritization
#Conflict Resolution
Product Manager
•
Behavioral
•
medium
Tell me about a time you had to say 'no' to a major client's feature request. How did you deliver the message?
#Negotiation
#Product Vision
#Client Relations
Product Manager
•
Behavioral
•
medium
Walk me through your process for conducting user research when the end-users are employees of a client company, not general consumers.
#B2B Product Management
#User Interviews
#Enterprise Software
Product Manager
•
Behavioral
•
medium
Describe a product launch that failed or underperformed. What went wrong and what did you learn?
#Failure Analysis
#Retrospectives
#Continuous Improvement
Product Manager
•
Behavioral
•
medium
How do you align a distributed team across different time zones (e.g., US onshore, India offshore) on a product roadmap?
#Distributed Teams
#Communication
#Agile Ceremonies
Product Manager
•
Coding
•
easy
Write a Python script or pseudo-code to parse a JSON log file and extract all user IDs that encountered a 500 Internal Server Error.
#Python
#Log Analysis
#Debugging
Product Manager
•
Coding
•
easy
Given an array of daily stock prices, write an algorithm to find the maximum profit you can achieve from a single buy and sell.
#Logic
#Optimization
#Arrays
Product Manager
•
Coding
•
medium
Write a SQL query to calculate the month-over-month retention rate of users on a subscription platform.
#Retention
#Advanced SQL
#Product Metrics
Product Manager
•
Coding
•
easy
Write a SQL query to find the top 3 most active users by transaction volume in the last 30 days for a fintech application.
#Data Analysis
#SQL
#Product Metrics
Product Manager
•
System Design
•
hard
Design a scalable ticketing system for a global IT helpdesk serving multiple Fortune 500 clients.
#Multi-tenancy
#Scalability
#Workflow Automation
Product Manager
•
System Design
•
hard
Design a healthcare patient portal for a major hospital network. What are the key features and how would you ensure HIPAA compliance?
#Healthcare
#Compliance
#User Experience
#Architecture
Product Manager
•
System Design
•
hard
Design an IoT-based fleet management dashboard for a logistics client. What metrics would you display and how would the data flow from trucks to the UI?
#IoT
#Real-time Data
#Dashboard Design
Product Manager
•
System Design
•
hard
Design an inventory management system for a retail client that syncs online e-commerce and physical store stock in real-time.
#Omnichannel
#Inventory
#Concurrency
Product Manager
•
System Design
•
medium
Design a video streaming platform tailored specifically for corporate training and onboarding.
#Video Streaming
#Enterprise Software
#Content Delivery
Product Manager
•
System Design
•
hard
Design a real-time fraud detection system for an e-commerce payment gateway.
#E-commerce
#Fraud Detection
#Low Latency
Product Manager
•
System Design
•
hard
Design an automated claims processing system for an insurance client utilizing machine learning for fraud detection.
#Insurance
#Machine Learning
#Automation
Product Manager
•
System Design
•
medium
How would you design the telemetry and analytics tracking for a newly launched mobile banking app?
#Mobile Apps
#Analytics
#Data Privacy
Product Manager
•
Technical
•
hard
You are tasked with building a new B2B SaaS billing platform for a client. How do you determine the pricing model?
#Pricing Strategy
#B2B SaaS
#Market Research
Product Manager
•
Technical
•
hard
How would you measure the hallucination rate and accuracy of an LLM-powered customer service chatbot before releasing it to a client?
#LLMs
#Quality Assurance
#Metrics
Product Manager
•
Technical
•
hard
Cognizant is pitching a new predictive maintenance tool to manufacturing clients. Create a high-level go-to-market strategy.
#Go-to-Market
#Manufacturing
#B2B Sales
Product Manager
•
Technical
•
medium
Explain microservices architecture to a business stakeholder and justify why we should migrate their legacy monolith.
#Microservices
#Legacy Modernization
#Business Value
Product Manager
•
Technical
•
medium
How do you balance building custom features for a specific high-paying client versus building scalable features for the broader market?
#Scalability
#Customization
#Roadmap Management
Product Manager
•
Technical
•
hard
A client is migrating their core systems from on-premise to AWS. As a PM, what are the key risks you need to track during this transition?
#Cloud Migration
#Risk Management
#AWS
Product Manager
•
Technical
•
medium
What security and compliance considerations would you prioritize when building a data lake for a healthcare client?
#Data Lakes
#HIPAA
#Data Governance
Product Manager
•
Technical
•
hard
A major enterprise client wants to integrate Generative AI into their legacy supply chain management system. How do you evaluate if this is the right product decision?
#Generative AI
#Legacy Modernization
#ROI Analysis
Product Manager
•
Technical
•
medium
How do you define and measure success for an internal developer productivity tool built for Cognizant's offshore teams?
#Internal Tools
#KPIs
#Developer Experience
Product Manager
•
Technical
•
medium
How would you explain the difference between REST and GraphQL to a non-technical client stakeholder who is deciding on an API strategy?
#APIs
#Stakeholder Communication
#System Integration
Product Manager
•
Technical
•
easy
If you were the PM for Cognizant's internal employee portal, what would be your top 3 features to improve employee engagement?
#Internal Tools
#Employee Engagement
#Ideation
Software Engineer
•
Behavioral
•
medium
Describe a time when you found a critical bug in production. What were your immediate steps?
#Incident Management
#Accountability
Software Engineer
•
Behavioral
•
easy
Why do you want to join Cognizant, and how do you align with our core values of client-centricity?
#Company Knowledge
#Motivation
Software Engineer
•
Behavioral
•
medium
Cognizant works heavily with legacy modernization. Tell me about a time you had to learn a completely new technology stack in a short period.
#Continuous Learning
#Agility
Software Engineer
•
Behavioral
•
medium
Describe a situation where you had a conflict with a team member regarding a technical decision. How did you resolve it?
#Conflict Resolution
#Collaboration
Software Engineer
•
Behavioral
•
medium
Tell me about a time you had to push back on a client's unrealistic deadline.
#Communication
#Negotiation
#Stakeholder Management
Software Engineer
•
Coding
•
easy
Detect a cycle in a linked list.
#Linked List
#Two Pointers
Software Engineer
•
Coding
•
medium
Find the longest substring without repeating characters.
#Strings
#Sliding Window
#Hash Table
Software Engineer
•
Coding
•
medium
Merge two sorted arrays into a single sorted array without using extra space (if the first array has enough buffer at the end).
#Arrays
#Two Pointers
Software Engineer
•
Coding
•
easy
Write a program to reverse a string without using any inbuilt functions like StringBuilder.reverse().
#Strings
#Two Pointers
Software Engineer
•
Coding
•
easy
Write a program to find the second highest number in an integer array.
#Arrays
#Iteration
Software Engineer
•
Coding
•
easy
Given two strings, write a function to check if they are anagrams of each other.
#Strings
#Hash Table
Software Engineer
•
Coding
•
medium
Implement an LRU (Least Recently Used) Cache.
#Design
#Hash Table
#Doubly Linked List
Software Engineer
•
Coding
•
easy
Find the first non-repeating character in a given string and return its index.
#Strings
#Hash Table
Software Engineer
•
Coding
•
medium
Print the left view of a Binary Tree.
#Binary Tree
#Breadth-First Search
#Depth-First Search
Software Engineer
•
System Design
•
hard
Explain the Saga design pattern for distributed transactions in microservices.
#Microservices
#Distributed Systems
#Transactions
Software Engineer
•
System Design
•
medium
Design a microservices architecture for a retail e-commerce application. How do the services communicate?
#Microservices
#API Gateway
#Service Discovery
Software Engineer
•
System Design
•
medium
Design a URL shortener service like Bitly.
#Scalability
#Database Design
#Hashing
Software Engineer
•
System Design
•
hard
How would you design a rate limiter for a public-facing API?
#API Gateway
#Algorithms
#Scalability
Software Engineer
•
System Design
•
medium
How do you handle database schema migrations in a CI/CD pipeline?
#Database Management
#CI/CD
#Flyway/Liquibase
Software Engineer
•
Technical
•
easy
What is Dependency Injection and Inversion of Control (IoC)? How does Spring implement it?
#Design Patterns
#Spring Core
#IoC Container
Software Engineer
•
Technical
•
medium
How do you handle exceptions globally in a Spring Boot application?
#Exception Handling
#Spring AOP
#Annotations
Software Engineer
•
Technical
•
easy
What is the difference between the Runnable and Callable interfaces in Java?
#Multithreading
#Concurrency
Software Engineer
•
Technical
•
medium
Explain the difference between HashMap and ConcurrentHashMap in Java.
#Collections
#Concurrency
Software Engineer
•
Technical
•
medium
Explain the concept of CI/CD. What tools have you used, and how do you configure a basic Jenkins pipeline?
#CI/CD
#Jenkins
#Deployment
Software Engineer
•
Technical
•
easy
What is the difference between @Component, @Service, and @Repository annotations in Spring?
#Spring Core
#Annotations
Software Engineer
•
Technical
•
medium
Explain the internal working of a HashMap in Java 8. What happens when a collision occurs?
#Data Structures
#Java Collections
#Hashing
Software Engineer
•
Technical
•
medium
Write a SQL query to find the nth highest salary from an Employee table.
#SQL Queries
#Subqueries
#Window Functions
Software Engineer
•
Technical
•
medium
What are the new features introduced in Java 8? Write a Stream API snippet to filter a list of employees by age greater than 30.
#Java 8
#Stream API
#Lambda Expressions
Software Engineer
•
Technical
•
easy
Explain the difference between @Controller and @RestController in Spring Boot.
#Spring MVC
#Annotations
#REST APIs
Software Engineer
•
Technical
•
medium
Explain the SOLID principles with real-world examples.
#Object-Oriented Design
#Clean Code
#SOLID
Software Engineer
•
Technical
•
medium
How does Garbage Collection work in Java, and what are the different types of garbage collectors?
#JVM
#Memory Management
#Garbage Collection
Software Engineer
•
Technical
•
medium
How do you secure a RESTful API? Explain JWT token-based authentication.
#REST APIs
#JWT
#Spring Security
Software Engineer
•
Technical
•
medium
What are the differences between clustered and non-clustered indexes in SQL?
#SQL
#Indexing
#Performance Optimization
Software Engineer
•
Technical
•
medium
Write a SQL query to fetch all employees who are also managers (using a self-join).
#SQL Queries
#Joins
Software Engineer
•
Technical
•
medium
Explain the Bean lifecycle in the Spring framework.
#Spring Core
#Bean Lifecycle
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