AI Engineer • Behavioral • hard

Tell me about an AI project where you had to balance innovation with reliability.

#Reliability #Innovation

Practice

AI Engineer • Behavioral • hard

Describe a situation where you had to debug a hard-to-reproduce AI model failure.

#Problem Solving

Practice

AI Engineer • Behavioral • hard

Describe an AI product you built from scratch. What were the key technical decisions?

#Product Development

Practice

AI Engineer • Behavioral • medium

How do you handle stakeholder uncertainty around AI capabilities and limitations?

#Stakeholders #Expectations

Practice

AI Engineer • Behavioral • medium

Tell me about a time you optimized an LLM application for cost or latency.

#Cost #Latency

Practice

AI Engineer • Behavioral • medium

Describe a time you had to choose between using an AI model and a simpler rule-based system.

#Tradeoffs #Pragmatism

Practice

AI Engineer • Behavioral • easy

How do you stay current with the fast-moving AI/ML research landscape?

#Research #Continuous Learning

Practice

AI Engineer • Behavioral • hard

Tell me about a time an AI system you built produced unexpected or harmful outputs.

#Responsibility #Ethics

Practice

AI Engineer • Coding • medium

Write a Python class to manage conversation history for a multi-turn chatbot.

#Chatbot #Memory

Practice

AI Engineer • Coding • medium

Write a retry mechanism with exponential backoff for LLM API calls.

#Reliability #APIs

Practice

AI Engineer • Coding • hard

Implement a simple RAG pipeline using Python, LangChain, and FAISS.

#RAG #Python

Practice

AI Engineer • Coding • hard

Implement a semantic chunking strategy for long documents.

#Chunking #Embeddings

Practice

AI Engineer • System Design • hard

How would you architect an AI platform that supports 1000 concurrent LLM requests?

#Scaling #LLM Serving

Practice

AI Engineer • System Design • hard

Design a real-time AI safety filter for user-generated content.

#Content Moderation #Real-Time

Practice

AI Engineer • System Design • hard

How would you build a multi-modal AI system that processes both text and images?

#Multi-Modal #Vision

Practice

AI Engineer • System Design • hard

Design an AI code review system that integrates with GitHub PRs.

#Code Review #LLM

Practice

AI Engineer • System Design • hard

Design a document question-answering system using RAG.

#RAG #Vector Search

Practice

AI Engineer • System Design • hard

Design an AI-powered customer support chatbot for an e-commerce platform.

#Chatbot #LLM

Practice

AI Engineer • System Design • hard

Design an AI agent system that can autonomously browse the web and complete tasks.

#Agents #Tool Use

Practice

AI Engineer • Technical • medium

How do you choose the right embedding model for a domain-specific search task?

#Embedding Models #Search

Practice

AI Engineer • Technical • medium

What is semantic search? How does it differ from keyword-based search?

#Semantic Search #NLP

Practice

AI Engineer • Technical • hard

Explain function calling / tool use in LLMs. How do you implement it?

#Function Calling #Tool Use

Practice

AI Engineer • Technical • medium

What is LangChain? What are its key components (Chains, Agents, Tools)?

#LangChain #Agents

Practice

AI Engineer • Technical • medium

How do you integrate OpenAI API or Gemini API into a production application?

#OpenAI #Gemini

Practice

AI Engineer • Technical • hard

Explain the difference between dense and sparse retrieval in RAG.

#Dense Retrieval #BM25

Practice

AI Engineer • Technical • hard

How do you evaluate retrieval quality in a RAG system?

#Evaluation #Retrieval

Practice

AI Engineer • Technical • hard

How do you evaluate the quality of an LLM-generated response?

#LLM Evaluation #RAGAS

Practice

AI Engineer • Technical • hard

Explain the concept of AI bias. How do you detect and mitigate it in production?

#Bias #Fairness

Practice

AI Engineer • Technical • hard

What is AI alignment? What are the key safety concerns with large-scale AI deployment?

#Alignment #Safety

Practice

AI Engineer • Technical • hard

What is Constitutional AI? How does Anthropic use it?

#Constitutional AI #Anthropic

Practice

AI Engineer • Technical • hard

How do you red-team an AI system?

#Red Teaming #Security

Practice

AI Engineer • Technical • medium

What are guardrails in LLM applications? How do they work?

#Guardrails #Output Filtering

Practice

AI Engineer • Technical • medium

What is streaming response from an LLM API? How do you implement it in a web app?

#Streaming #API

Practice

AI Engineer • Technical • medium

How do you manage LLM API rate limits and costs in production?

#Rate Limiting #Cost

Practice

AI Engineer • Technical • medium

Explain structured output generation from LLMs (JSON mode, Instructor library).

#Structured Output #JSON

Practice

AI Engineer • Technical • hard

Explain the difference between GPT, BERT, and T5 architectures.

#GPT #BERT #T5

Practice

AI Engineer • Technical • medium

What is prompt engineering? What are few-shot, zero-shot, and chain-of-thought prompting?

#Prompt Engineering #Few-Shot

Practice

AI Engineer • Technical • hard

Explain how RLHF (Reinforcement Learning from Human Feedback) improves LLMs.

#RLHF #Alignment

Practice

AI Engineer • Technical • hard

What is RAG (Retrieval-Augmented Generation)? When would you use it over fine-tuning?

#RAG #Fine-Tuning

Practice

AI Engineer • Technical • medium

Explain the difference between fine-tuning and in-context learning.

#Fine-Tuning #ICL

Practice

AI Engineer • Technical • medium

What is token context window? How do you handle documents longer than the context limit?

#Context Window #Chunking

Practice

AI Engineer • Technical • hard

Explain positional encoding in transformers. What are the differences between absolute and rotary position embeddings?

#Positional Encoding #RoPE

Practice

AI Engineer • Technical • hard

What is hallucination in LLMs? How do you detect and mitigate it?

#Hallucination #Safety

Practice

AI Engineer • Technical • medium

Explain the difference between autoregressive and masked language modeling.

#Autoregressive #Masked LM

Practice

AI Engineer • Technical • hard

What is a mixture of experts (MoE) architecture? How does it scale?

#MoE #Scaling

Practice

AI Engineer • Technical • hard

Explain how vector similarity search works. What are HNSW and IVF indices?

#HNSW #Similarity Search

Practice

AI Engineer • Technical • medium

Compare vector databases: Pinecone, Weaviate, Qdrant, and pgvector.

#Vector DB #Embeddings

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you improved the reliability of a cloud-based data system.

#SRE #Impact

Practice

Cloud Engineer • Behavioral • medium

Describe a situation where you had to choose between two cloud architectures. How did you decide?

#Architecture #Tradeoffs

Practice

Cloud Engineer • Behavioral • medium

How do you communicate a complex cloud architecture to non-technical stakeholders?

#Stakeholders

Practice

Cloud Engineer • Behavioral • medium

Describe your experience with incident post-mortems. What do you include?

#Post-Mortem #Learning

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you had to optimize a system or infrastructure to reduce costs or improve efficiency. What metrics did you use to measure success?

#Efficiency #Impact #Metrics

Practice

Cloud Engineer • Behavioral • hard

Tell me about a major cloud outage you experienced. How did you respond?

#Outage #On-Call

Practice

Cloud Engineer • Behavioral • hard

Describe a time you migrated a critical workload to the cloud with zero downtime.

#Cloud Migration

Practice

Cloud Engineer • Behavioral • medium

Describe a situation where you strongly disagreed with a senior engineer or a cross-functional partner on an architectural decision. How did you resolve the conflict?

#Conflict Resolution #Communication #Data-Driven Decisions

Practice

Cloud Engineer • Behavioral • easy

How do you stay updated with new cloud services and features?

#Continuous Learning

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you caused a significant production outage. How did you handle the immediate mitigation, and what was the post-mortem process?

#Incident Management #Ownership #Blameless Culture

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you significantly reduced cloud infrastructure costs.

#FinOps #Impact

Practice

Cloud Engineer • Coding • medium

Given a massive, 100GB web server log file, write a script to find the top K most frequent IP addresses making requests. The script must run on a machine with only 4GB of RAM.

#Log Parsing #Memory Management #Heaps #Hash Maps

Practice

Cloud Engineer • Coding • easy

Write a function to validate if a given string is a valid IPv4 or IPv6 address. Do not use built-in IP validation libraries.

#String Manipulation #Validation #Edge Cases

Practice

Cloud Engineer • Coding • hard

Implement a thread-safe bounded blocking queue. It should support enqueue and dequeue operations, blocking if the queue is full or empty, respectively.

#Multithreading #Synchronization #Data Structures

Practice

Cloud Engineer • Coding • medium

Write a concurrent script in Python or Go to monitor a local directory for new files and upload them to a remote storage service. It must handle network failures and retries gracefully.

#Concurrency #Error Handling #File I/O #Asynchronous Programming

Practice

Cloud Engineer • System Design • hard

How would you set up a streaming data pipeline on GCP using Pub/Sub and Dataflow?

#GCP #Pub/Sub #Dataflow

Practice

Cloud Engineer • System Design • hard

How would you architect a data platform that reduces spend by 40% without impacting performance?

#FinOps #Cloud

Practice

Cloud Engineer • System Design • hard

How do you implement disaster recovery for a cloud data warehouse?

#DR #RTO #RPO

Practice

Cloud Engineer • System Design • hard

Design a photo storage system similar to what Instagram uses. It must handle billions of reads and millions of writes per day with extremely low latency.

#Blob Storage #CDN #Caching #Database Scaling

Practice

Cloud Engineer • System Design • medium

Design a distributed caching system for Meta's newsfeed. How do you handle cache invalidation and the 'thundering herd' problem?

#Caching #Distributed Systems #Memcached

Practice

Cloud Engineer • System Design • hard

Design a globally distributed rate limiter for Meta's Graph API. It needs to handle millions of requests per second and enforce limits based on user ID and application ID.

#Rate Limiting #Distributed Systems #Redis #Concurrency

Practice

Cloud Engineer • System Design • hard

Design a data lake on AWS using S3, Glue, and Athena.

#AWS #S3 #Athena

Practice

Cloud Engineer • Technical • medium

How do cloud IAM roles and policies work? Explain least-privilege principle.

#IAM #Permissions

Practice

Cloud Engineer • Technical • medium

What is AWS PrivateLink? When would you use it?

#PrivateLink #VPC

Practice

Cloud Engineer • Technical • hard

How would you implement network segmentation for a multi-tier application?

#Security #Subnets

Practice

Cloud Engineer • Technical • medium

What are SLOs, SLAs, and SLIs? How do you define them for a data platform?

#SLO #Reliability

Practice

Cloud Engineer • Technical • hard

Explain chaos engineering. How would you implement it for a data pipeline?

#Chaos Engineering #Fault Injection

Practice

Cloud Engineer • Technical • medium

How do you do capacity planning for a cloud data platform?

#Scaling #Planning

Practice

Cloud Engineer • Technical • easy

What is a runbook? How do you create effective runbooks for data infrastructure?

#Runbook #On-Call

Practice

Cloud Engineer • Technical • medium

Explain the three pillars of observability: logs, metrics, and traces.

#Logs #Metrics #Traces

Practice

Cloud Engineer • Technical • medium

How would you set up CloudWatch dashboards for a data pipeline?

#CloudWatch #AWS

Practice

Cloud Engineer • Technical • medium

What is OpenTelemetry? How does it standardize observability?

#OpenTelemetry #Tracing

Practice

Cloud Engineer • Technical • medium

What happens exactly when a process runs out of memory in Linux? Explain the OOM Killer mechanism and how you would configure a critical database process to avoid being killed.

#Memory Management #OOM Killer #Kernel Tuning

Practice

Cloud Engineer • Technical • medium

Explain the difference between TCP and UDP. How does the QUIC protocol improve upon TCP, and why would Meta use it for video streaming or WhatsApp calls?

#Protocols #TCP/UDP #QUIC #Latency

Practice

Cloud Engineer • Technical • hard

You notice a sudden spike in 5xx HTTP errors from a specific microservice cluster. Walk me through your exact debugging steps from the edge load balancer down to the application layer.

#Microservices #Debugging #Observability

Practice

Cloud Engineer • Technical • medium

Explain the exact difference between an L4 load balancer and an L7 load balancer. Describe how Direct Server Return (DSR) works in a massive scale environment like Meta's.

#Load Balancing #OSI Model #TCP/IP #DSR

Practice

Cloud Engineer • Technical • hard

You are paged because a Linux server is experiencing a high load average (e.g., 40 on a 16-core machine), but CPU utilization is under 10%. How do you troubleshoot this?

#OS Troubleshooting #I/O Wait #Process States

Practice

Cloud Engineer • Technical • hard

Compare AWS, GCP, and Azure for a data-intensive workload. What are the key differentiators?

#AWS #GCP #Azure

Practice

Cloud Engineer • Technical • medium

What is the shared responsibility model in cloud security?

#Cloud Security #IAM

Practice

Cloud Engineer • Technical • easy

Explain IaaS, PaaS, and SaaS with examples.

#IaaS #PaaS #SaaS

Practice

Cloud Engineer • Technical • hard

What is a VPC (Virtual Private Cloud)? How do you design a secure VPC architecture?

#VPC #Security

Practice

Cloud Engineer • Technical • easy

Explain the difference between regions, availability zones, and edge locations.

#Regions #AZs

Practice

Cloud Engineer • Technical • medium

How does auto-scaling work? What are the different scaling strategies?

#Auto-Scaling #EC2

Practice

Cloud Engineer • Technical • medium

What is a cloud-native application? How does it differ from a lifted-and-shifted one?

#Cloud Native #Migration

Practice

Cloud Engineer • Technical • hard

Explain multi-cloud vs hybrid cloud architectures and their tradeoffs.

#Multi-Cloud #Hybrid

Practice

Cloud Engineer • Technical • hard

Explain Kubernetes architecture: control plane, nodes, pods, and services.

#K8s #Containers

Practice

Cloud Engineer • Technical • hard

What is a Kubernetes Operator and when would you build one?

#Operators #CRD

Practice

Cloud Engineer • Technical • hard

How does container networking work in Kubernetes?

#Networking #CNI

Practice

Cloud Engineer • Technical • medium

Explain Kubernetes resource requests vs limits. What happens if a pod exceeds its memory limit?

#Resources #OOM

Practice

Cloud Engineer • Technical • hard

What is a service mesh? Explain how Istio works.

#Istio #Service Mesh

Practice

Cloud Engineer • Technical • hard

How would you set up horizontal pod autoscaling based on custom metrics?

#HPA #Custom Metrics

Practice

Cloud Engineer • Technical • medium

Explain the difference between Docker and containerd.

#Docker #containerd

Practice

Cloud Engineer • Technical • medium

How does a Kubernetes Ingress controller work?

#Ingress #Load Balancing

Practice

Cloud Engineer • Technical • hard

Explain Terraform's state management. What happens if the state file is corrupted?

#IaC #State

Practice

Cloud Engineer • Technical • medium

What is the difference between Terraform and Pulumi?

#Terraform #Pulumi

Practice

Cloud Engineer • Technical • medium

How do you manage secrets in cloud infrastructure? (HashiCorp Vault, AWS Secrets Manager)

#Secrets Management #Vault

Practice

Cloud Engineer • Technical • medium

Explain idempotency in infrastructure provisioning.

#Idempotency #Terraform

Practice

Cloud Engineer • Technical • hard

How do you handle Terraform state across multiple teams?

#State Management #Collaboration

Practice

Cloud Engineer • Technical • hard

Compare AWS EMR, GCP Dataproc, and Azure HDInsight for Spark workloads.

#EMR #Dataproc #Spark

Practice

Cloud Engineer • Technical • medium

Explain the difference between AWS Lambda and EC2 for data processing.

#Lambda #Serverless

Practice

Cloud Engineer • Technical • hard

What is BigQuery Slots? How do you optimize BigQuery query costs?

#GCP #Cost

Practice

Cloud Engineer • Technical • medium

Explain AWS S3 storage classes and lifecycle policies.

#S3 #Cost

Practice

Cloud Engineer • Technical • medium

How does AWS Glue Data Catalog work with Athena?

#Glue #Athena

Practice

Cloud Engineer • Technical • hard

What is zero-trust networking? How do you implement it on cloud?

#Zero Trust #Networking

Practice

Cloud Engineer • Technical • medium

Explain TLS/SSL termination in a cloud load balancer.

#TLS #Load Balancer

Practice

Data Analyst • Behavioral • medium

How do you handle a situation where a stakeholder challenges your analysis?

#Stakeholders #Confidence

Practice

Data Analyst • Behavioral • medium

Describe a time you found an insight that was counterintuitive.

#Curiosity

Practice

Data Analyst • Behavioral • hard

Tell me about a time you had incomplete data but still needed to deliver analysis.

#Ambiguity

Practice

Data Analyst • Behavioral • medium

How do you prioritize analytical requests when multiple teams need you?

#Time Management

Practice

Data Analyst • Behavioral • medium

Describe a dashboard you built that was widely adopted. What made it successful?

#Visualization

Practice

Data Analyst • Behavioral • medium

Tell me about a time you discovered data quality issues mid-analysis. What did you do?

#Problem Solving

Practice

Data Analyst • Behavioral • easy

How do you ensure your analyses are reproducible?

#Reproducibility

Practice

Data Analyst • Behavioral • medium

Tell me about an analysis that changed a major business decision.

#Business Impact #Influence

Practice

Data Analyst • Coding • medium

Explain window functions. Write a query using LAG() to compute day-over-day change.

#Window Functions

Practice

Data Analyst • Coding • hard

What is a funnel query? Write one for a 3-step user onboarding flow.

#Funnel Analysis

Practice

Data Analyst • Coding • medium

What is a pivot table in SQL? How would you implement it without native PIVOT support?

#Pivot #Data Transformation

Practice

Data Analyst • Coding • hard

Write a SQL query to find customers who made purchases in both January and February but not March.

#Set Operations

Practice

Data Analyst • Coding • hard

Write a SQL query to calculate the rolling 28-day average session duration per user.

#Rolling Average #Sessions

Practice

Data Analyst • Coding • hard

How would you build a cohort analysis for user retention in SQL?

#Cohort Analysis #Retention

Practice

Data Analyst • Coding • medium

Write a SQL query to calculate month-over-month revenue growth.

#Revenue #Growth Analytics

Practice

Data Analyst • Coding • medium

How would you use pandas to compute a 7-day rolling average of sessions?

#Pandas #Time Series

Practice

Data Analyst • Coding • easy

Explain how groupby and agg work in pandas with an example.

#Pandas #GroupBy

Practice

Data Analyst • Coding • medium

How would you merge two large DataFrames efficiently in pandas?

#Pandas #Merging

Practice

Data Analyst • Coding • medium

Describe how to detect and handle outliers in a dataset using Python.

#Outliers #Data Cleaning

Practice

Data Analyst • Coding • easy

Write Python code to load a CSV, clean missing values, and compute summary statistics.

#Data Cleaning #Pandas

Practice

Data Analyst • Coding • hard

How would you detect anomalies in a daily revenue time series using SQL?

#Anomaly Detection #SQL

Practice

Data Analyst • Technical • easy

What is ARPU (Average Revenue Per User)? How do you segment ARPU analysis?

#ARPU #Revenue

Practice

Data Analyst • Technical • medium

How would you measure the success of a new feature launch?

#Feature Success #Metrics

Practice

Data Analyst • Technical • easy

Explain the difference between DAU, WAU, and MAU. Which is most useful and when?

#Engagement #KPIs

Practice

Data Analyst • Technical • medium

What is customer lifetime value (LTV)? How would you calculate it?

#LTV #Retention

Practice

Data Analyst • Technical • hard

Daily Active Users dropped 15% yesterday. Walk me through how you'd investigate.

#Root Cause Analysis #Metrics

Practice

Data Analyst • Technical • medium

How do you handle timezone conversions in SQL analytics?

#Timezones #Analytics

Practice

Data Analyst • Technical • easy

Explain the difference between a HAVING clause and a WHERE clause.

#SQL Basics

Practice

Data Analyst • Technical • medium

Describe your process for creating an executive-level analytics presentation.

#Executive Reporting

Practice

Data Analyst • Technical • easy

How do you choose between a bar chart, line chart, and scatter plot?

#Charts #Design

Practice

Data Analyst • Technical • easy

What tools do you use for dashboarding? Compare Tableau, Looker, and Metabase.

#Tableau #Looker

Practice

Data Analyst • Technical • medium

How would you explain statistical significance to a non-technical product manager?

#Storytelling #Statistics

Practice

Data Analyst • Technical • medium

What makes a good data visualization? Walk me through your design principles.

#Design #Communication

Practice

Data Analyst • Technical • hard

How do you handle multiple metrics in an A/B test (metric tradeoffs)?

#Multiple Metrics #Tradeoffs

Practice

Data Analyst • Technical • medium

What is a novelty effect in experimentation? How do you account for it?

#Novelty Effect #Bias

Practice

Data Analyst • Technical • hard

A/B test shows p=0.04, but the effect size is tiny. Would you ship?

#Practical Significance #Decision Making

Practice

Data Analyst • Technical • hard

What sample size do you need for an A/B test? How do you calculate it?

#Sample Size #Power

Practice

Data Analyst • Technical • hard

Explain how you'd set up an A/B test to validate a new checkout flow.

#A/B Testing #Statistics

Practice

Data Analyst • Technical • hard

How would you measure the impact of a pricing change on revenue?

#Pricing #A/B Test

Practice

Data Analyst • Technical • easy

What is net promoter score (NPS)? How do you analyse NPS trends?

#NPS #Customer Satisfaction

Practice

Data Analyst • Technical • hard

What metrics would you use to measure the health of a marketplace?

#Marketplace #Supply & Demand

Practice

Data Analyst • Technical • medium

How would you build a dashboard to monitor e-commerce funnel health?

#Visualization #Funnel

Practice

Data Analyst • Technical • hard

Explain the concept of attribution modeling. What are last-click vs multi-touch models?

#Marketing Analytics

Practice

Data Engineer • Behavioral • medium

How do you handle disagreements with data analysts or scientists who want features that compromise pipeline reliability?

#Conflict Resolution

Practice

Data Engineer • Behavioral • medium

Describe a situation where a data pipeline you owned went down in production. How did you handle it?

#On-Call #Problem Solving

Practice

Data Engineer • Behavioral • medium

Tell me about a time you simplified a complex data platform decision across multiple teams.

#Communication #Stakeholders

Practice

Data Engineer • Behavioral • medium

Tell me about a time you had a disagreement with a cross-functional partner (like a Data Scientist or Product Manager) regarding the definition of a metric or a data pipeline requirement. How did you resolve it?

#Conflict Resolution #Communication #Cross-functional Collaboration

Practice

Data Engineer • Behavioral • medium

Tell me about a time you identified a major bottleneck or inefficiency in an existing data pipeline. What steps did you take to optimize it, and what was the impact?

#Impact #Proactivity #Optimization

Practice

Data Engineer • Behavioral • easy

How do you stay current with rapidly evolving data engineering tools and practices?

#Growth Mindset

Practice

Data Engineer • Behavioral • easy

Describe your experience mentoring junior data engineers.

#Mentoring #Collaboration

Practice

Data Engineer • Behavioral • medium

Tell me about a time you onboarded a new data source that had significant quality issues.

#Problem Solving

Practice

Data Engineer • Behavioral • hard

Describe how you've balanced technical debt vs. new feature development in a data platform.

#Prioritization

Practice

Data Engineer • Behavioral • medium

Tell me about a time you significantly improved the performance of a data system.

#Performance #Optimization

Practice

Data Engineer • Coding • easy

Given a `friend_requests` table (sender_id, receiver_id, date, status) and an `acceptances` table, write a SQL query to find the overall acceptance rate of friend requests by date.

#Joins #Aggregations #Ratios

Practice

Data Engineer • Coding • medium

Given a `user_logins` table with `user_id` and `login_date`, write a SQL query to calculate the 7-day rolling average of Daily Active Users (DAU) for the last 30 days.

#Window Functions #Rolling Averages #DAU

Practice

Data Engineer • Coding • easy

Given an array of integers representing the number of likes on a user's posts, write a Python function to move all zeros (posts with zero likes) to the end of the array while maintaining the relative order of the non-zero elements. Do this in-place.

#Arrays #Two Pointers #In-place Manipulation

Practice

Data Engineer • Coding • medium

Write a Python script to parse a massive JSONL file (100GB+) containing WhatsApp message metadata. Calculate the total number of messages sent per country code. You cannot load the entire file into memory.

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

Practice

Data Engineer • Coding • medium

Write a SQL query to find users who have interacted with a Meta ad and subsequently made a purchase on the advertiser's website within 24 hours. You have an `ad_clicks` table and a `conversions` table.

#Joins #Date/Time Functions #Attribution

Practice

Data Engineer • Coding • medium

Write a SQL query to compute a 7-day rolling average of daily sales.

#Window Functions #Analytics

Practice

Data Engineer • Coding • medium

Write a SQL query to find the second highest salary per department.

#Window Functions #SQL

Practice

Data Engineer • Coding • hard

Write a SQL query to calculate the retention rate of new users on a 1-day, 7-day, and 30-day basis. You are given a `user_activity` table with `user_id` and `activity_date`.

#Cohort Analysis #Retention #Self Joins #Conditional Aggregation

Practice

Data Engineer • Coding • medium

Given a list of dictionaries representing Facebook post interactions (user_id, post_id, interaction_type, timestamp), write a Python script to return the top 3 most engaged posts for each interaction type.

#Dictionaries #Heaps #Data Aggregation

Practice

Data Engineer • Coding • medium

Write a Python function to merge overlapping user session intervals. Given an array of intervals where intervals[i] = [start_i, end_i], merge all overlapping intervals and return an array of the non-overlapping intervals.

#Arrays #Sorting #Intervals

Practice

Data Engineer • System Design • hard

How would you design a data warehouse for a ride-sharing company from scratch?

#Architecture #Design

Practice

Data Engineer • System Design • hard

Design a system to detect ad-click fraud in real-time. The system processes billions of events per day and needs to flag suspicious IPs or user accounts within seconds.

#Real-time Processing #Fraud Detection #Distributed Systems #Caching

Practice

Data Engineer • System Design • hard

Design a data pipeline to process and store telemetry data for Instagram Reels. The pipeline needs to support real-time dashboarding for creators and batch processing for machine learning recommendations.

#Lambda Architecture #Kafka #Stream Processing #Data Warehousing

Practice

Data Engineer • System Design • hard

Design an ad delivery data pipeline that tracks impressions at 10M/sec.

#Streaming #Scale

Practice

Data Engineer • System Design • hard

How would you design Meta's data pipeline for News Feed ranking signals?

#Ranking #Pipeline

Practice

Data Engineer • System Design • hard

Design an ETL pipeline that ingests 10TB of raw clickstream data daily.

#ETL #Batch Processing

Practice

Data Engineer • System Design • hard

Design a data model for an e-commerce platform tracking orders, users, and products.

#ER Modeling #Dimensional Modeling

Practice

Data Engineer • System Design • hard

How would you design a real-time anomaly detection pipeline for 100K events/sec?

#Real-Time #Anomaly Detection

Practice

Data Engineer • System Design • hard

How would you design a data pipeline that needs exactly-once delivery guarantees?

#Exactly-Once #Kafka

Practice

Data Engineer • Technical • hard

Explain how Meta uses Scribe for structured logging at petabyte scale.

#Scribe #Infrastructure

Practice

Data Engineer • Technical • medium

Explain the difference between OLAP and OLTP systems. When would you use each?

#OLAP #OLTP #Databases

Practice

Data Engineer • Technical • hard

What is a slowly changing dimension (SCD)? Describe SCD Type 1, 2, and 3 with examples.

#SCD #Dimensional Modeling

Practice

Data Engineer • Technical • hard

How would you optimize a SQL query that is running slowly on a 1 billion row table?

#Query Optimization #Indexing

Practice

Data Engineer • Technical • medium

Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER().

#Window Functions #SQL

Practice

Data Engineer • Technical • medium

What is a materialized view? How does it differ from a regular view?

#Materialized Views #Performance

Practice

Data Engineer • Technical • hard

Describe partitioning strategies in a data warehouse. When would you use range vs hash partitioning?

#Partitioning #Performance

Practice

Data Engineer • Technical • medium

What are CTEs (Common Table Expressions) and how do they differ from subqueries?

#CTEs #SQL

Practice

Data Engineer • Technical • medium

Explain ACID properties. Which databases sacrifice ACID for performance and why?

#ACID #Distributed Systems

Practice

Data Engineer • Technical • hard

How do you handle late-arriving data in a streaming pipeline?

#Kafka #Watermarks

Practice

Data Engineer • Technical • medium

What is idempotency and why is it critical in data pipelines?

#Idempotency #Data Quality

Practice

Data Engineer • Technical • hard

Explain the Lambda architecture. What are its tradeoffs vs Kappa architecture?

#Lambda #Kappa #Streaming

Practice

Data Engineer • Technical • hard

What is backfilling? How do you handle a backfill of 2 years of historical data without impacting production?

#Backfill #Airflow

Practice

Data Engineer • Technical • medium

How do you monitor data pipeline health in production? What metrics do you track?

#Monitoring #Alerting

Practice

Data Engineer • Technical • medium

What is Apache Airflow? How does it differ from Prefect or Dagster?

#Airflow #Prefect #Dagster

Practice

Data Engineer • Technical • easy

Explain the difference between push-based and pull-based data ingestion.

#Push #Pull #CDC

Practice

Data Engineer • Technical • hard

Explain how Apache Spark's execution model works. What is a DAG in Spark?

#Spark #DAG #Distributed Computing

Practice

Data Engineer • Technical • hard

What is data skew in Spark? How do you diagnose and fix it?

#Data Skew #Performance

Practice

Data Engineer • Technical • hard

Explain the difference between map-side and reduce-side joins in MapReduce/Spark.

#Joins #MapReduce

Practice

Data Engineer • Technical • medium

What is Apache Kafka? Explain topics, partitions, consumer groups, and offsets.

#Kafka #Streaming

Practice

Data Engineer • Technical • medium

How does Kafka handle message ordering guarantees?

#Ordering #Partitions

Practice

Data Engineer • Technical • medium

What is the CAP theorem? Give an example of a real-world system tradeoff.

#CAP #Consistency #Availability

Practice

Data Engineer • Technical • medium

Explain how Parquet and ORC file formats work and when you'd use each.

#Parquet #ORC #Columnar

Practice

Data Engineer • Technical • hard

What is Delta Lake? How does it provide ACID transactions on data lakes?

#Delta Lake #ACID #Time Travel

Practice

Data Engineer • Technical • medium

Explain compaction in Delta Lake / Iceberg. Why is it important?

#Compaction #Performance

Practice

Data Engineer • Technical • medium

What is the star schema vs snowflake schema? When would you use each?

#Star Schema #Snowflake Schema

Practice

Data Engineer • Technical • hard

What is Data Vault methodology? How does it differ from Kimball?

#Data Vault #Kimball

Practice

Data Engineer • Technical • medium

Explain the concept of a data lakehouse. What are its advantages over a traditional data warehouse?

#Data Lakehouse #Data Warehouse

Practice

Data Engineer • Technical • hard

How do you handle schema evolution in a data pipeline without breaking downstream consumers?

#Schema Evolution #Backward Compatibility

Practice

Data Engineer • Technical • medium

What is a medallion architecture (Bronze/Silver/Gold)?

#Medallion #Data Lake

Practice

Data Engineer • Technical • medium

How do you implement data quality checks in a production pipeline?

#Great Expectations #Data Validation

Practice

Data Engineer • Technical • medium

What is data lineage and why is it important? How do you implement it?

#Lineage #Metadata

Practice

Data Engineer • Technical • hard

How would you detect and handle data drift in a production system?

#Data Drift #Monitoring

Practice

Data Engineer • Technical • medium

What is PII (Personally Identifiable Information) and how do you handle it in a data pipeline?

#PII #Privacy #Compliance

Practice

Data Engineer • Technical • medium

Explain the concept of a data catalog. What tools have you used?

#Data Catalog #Metadata

Practice

Data Engineer • Technical • hard

Compare AWS Redshift, Google BigQuery, and Snowflake for a petabyte-scale warehouse.

#Redshift #BigQuery #Snowflake

Practice

Data Engineer • Technical • hard

How does BigQuery handle large joins efficiently? What is its columnar storage approach?

#BigQuery #Columnar Storage

Practice

Data Engineer • Technical • medium

Explain the difference between S3, HDFS, and GCS for data storage.

#S3 #HDFS #GCS

Practice

Data Engineer • Technical • medium

How would you reduce costs in a cloud-based data platform?

#Cloud #Cost

Practice

Data Engineer • Technical • medium

What is infrastructure as code (IaC)? Have you used Terraform for data infrastructure?

#Terraform #IaC

Practice

Data Engineer • Technical • hard

What is Presto? How does Meta use it at scale?

#Presto #SQL

Practice

Data Engineer • Technical • medium

Describe how you'd implement circuit breakers in a data pipeline.

#Circuit Breakers #Fault Tolerance

Practice

Data Engineer • Technical • hard

How would you handle data consistency across Meta's global sharded MySQL?

#Sharding #Consistency

Practice

Data Engineer • Technical • medium

Design the data model for Facebook Marketplace. We need to track users, product listings, categories, and transactions. How would you structure the fact and dimension tables to allow product managers to analyze daily sales volume by category and user demographics?

#Dimensional Modeling #Star Schema #Fact Tables #Dimension Tables

Practice

Data Engineer • Technical • hard

How would you handle late-arriving data in a daily ETL pipeline that computes Facebook's Daily Active Users (DAU)? Assume the pipeline runs at 2 AM UTC, but mobile clients might upload offline logs days later.

#ETL #Late-Arriving Data #Idempotency #Backfilling

Practice

Data Engineer • Technical • medium

How do you design a Slowly Changing Dimension (SCD) Type 2 table for Facebook user profiles? Explain how you would handle updates to a user's 'current_city' while preserving the history of their previous locations.

#SCD Type 2 #Data Warehousing #Historical Tracking

Practice

Data Scientist • Behavioral • medium

Tell me about a time when you discovered a significant flaw in your own analysis after you had already presented the findings to leadership. What did you do?

#Integrity #Accountability #Communication

Practice

Data Scientist • Behavioral • medium

Tell me about a data science project where the results surprised you. What did you do?

#Analytical Thinking

Practice

Data Scientist • Behavioral • medium

Describe how you communicated a complex model result to a non-technical stakeholder.

#Storytelling

Practice

Data Scientist • Behavioral • hard

Tell me about a time you had to push back on a business request for an analysis that would be misleading.

#Ethics #Communication

Practice

Data Scientist • Behavioral • medium

Describe a project where you had to iterate significantly on your initial approach.

#Iteration #Learning

Practice

Data Scientist • Behavioral • medium

How do you prioritize between multiple data science requests from different teams?

#Stakeholder Management

Practice

Data Scientist • Behavioral • hard

Tell me about a time your model failed in production. What did you learn?

#Production #MLOps

Practice

Data Scientist • Behavioral • medium

How do you approach ethical considerations in ML model building?

#Fairness #Bias

Practice

Data Scientist • Behavioral • hard

Describe a time you used data to challenge a widely held assumption in your organization.

#Influence #Analytics

Practice

Data Scientist • Behavioral • medium

Tell me about a time when you strongly disagreed with a Product Manager about the interpretation of an A/B test result. How did you handle it and what was the outcome?

#Conflict Resolution #Stakeholder Management #Communication

Practice

Data Scientist • Coding • hard

Write a SQL query to calculate 30-day user retention.

#Retention #Analytics

Practice

Data Scientist • Coding • hard

How would you write a funnel analysis query in SQL?

#Funnel #Analytics

Practice

Data Scientist • Coding • medium

Write a query to identify duplicate records and deduplicate them.

#Deduplication #Data Quality

Practice

Data Scientist • Coding • hard

Given a table `friend_requests` (sender_id, receiver_id, date, status), write a SQL query to calculate the overall friend acceptance rate for each day. Note that a request sent on day 1 might be accepted on day 3.

#Self Joins #Window Functions #Ratio Calculation

Practice

Data Scientist • Coding • medium

Given a pandas DataFrame containing user login logs with columns `user_id` and `login_timestamp`, write a Python function to find the longest consecutive streak of login days for each user.

#Python #Pandas #Data Manipulation

Practice

Data Scientist • Coding • medium

Write a SQL query to calculate the 7-day rolling retention rate of users who signed up through a specific marketing campaign. You have a `users` table (user_id, signup_date, campaign_id) and a `user_activity` table (user_id, activity_date).

#Retention #Rolling Metrics #Joins

Practice

Data Scientist • Coding • medium

Given two tables: `ad_campaigns` (campaign_id, advertiser_id, spend) and `ad_clicks` (click_id, campaign_id, user_id, timestamp), write a SQL query to find the top 5 advertisers with the highest number of clicks per dollar spent who have spent at least $10,000 in the last 30 days.

#Joins #Aggregations #Date Functions

Practice

Data Scientist • System Design • hard

Design a feature store. What are its key components?

#Feature Store #MLOps

Practice

Data Scientist • System Design • hard

We are evaluating a new machine learning model for the Facebook News Feed ranking. The offline AUC is significantly higher than the production model, but an online A/B test shows no change in user engagement. What could be causing this discrepancy?

#Model Evaluation #Offline vs Online Metrics #Ranking

Practice

Data Scientist • System Design • hard

How would you build a recommendation system? Compare collaborative vs content-based filtering.

#Collaborative Filtering #Content-Based

Practice

Data Scientist • System Design • hard

Design a real-time fraud detection system for a payments platform.

#Fraud Detection #Real-Time ML

Practice

Data Scientist • System Design • hard

How would you build and deploy a churn prediction model?

#Churn #MLOps

Practice

Data Scientist • System Design • hard

We want to test a new feature in Facebook Groups that relies heavily on user interaction. How would you design an A/B test for this feature, keeping in mind that treating one user might affect the experience of another user in the same group?

#Network Effects #Cluster Randomization #A/B Testing

Practice

Data Scientist • Technical • medium

What is transfer learning? How would you fine-tune a pre-trained model?

#Transfer Learning #Fine-Tuning

Practice

Data Scientist • Technical • medium

What is embedding? How do word embeddings like Word2Vec and GloVe work?

#Embeddings #Word2Vec

Practice

Data Scientist • Technical • medium

Explain batch normalization and why it helps training.

#Batch Normalization #Training

Practice

Data Scientist • Technical • medium

What is a confidence interval? How does it differ from a prediction interval?

#Confidence Interval #Intervals

Practice

Data Scientist • Technical • hard

Explain the curse of dimensionality and its implications for ML models.

#Dimensionality #Feature Engineering

Practice

Data Scientist • Technical • medium

How would you detect and handle multicollinearity in a regression model?

#Multicollinearity #Regression

Practice

Data Scientist • Technical • hard

Explain gradient boosting. How does XGBoost differ from a standard gradient boosting machine?

#Gradient Boosting #XGBoost

Practice

Data Scientist • Technical • medium

How does a Random Forest work? What are its hyperparameters and how do you tune them?

#Random Forest #Hyperparameter Tuning

Practice

Data Scientist • Technical • medium

What is regularization? Explain L1 vs L2 regularization and their effects.

#Regularization #L1 #L2

Practice

Data Scientist • Technical • medium

How do you handle class imbalance in a classification problem?

#Imbalanced Data #SMOTE

Practice

Data Scientist • Technical • medium

Explain the ROC curve and AUC metric. When would you prefer AUC over accuracy?

#ROC #AUC #Metrics

Practice

Data Scientist • Technical • hard

If we introduce a new ad format in the Instagram feed that increases ad revenue by 10% but decreases user time spent by 1%, how do you decide whether to roll this out globally?

#Trade-offs #LTV #Monetization

Practice

Data Scientist • Technical • hard

Meta wants to estimate the proportion of fake accounts on the platform. Since we cannot manually review billions of accounts, how would you design a sampling strategy to estimate this proportion with a 95% confidence interval and a 1% margin of error?

#Sampling #Confidence Intervals #Sample Size Calculation

Practice

Data Scientist • Technical • medium

Facebook Marketplace is seeing a high number of items listed but a low number of transactions completed. What metrics would you look at to understand where the friction is, and what product changes would you propose?

#Funnel Analysis #Marketplace #Conversion Rate

Practice

Data Scientist • Technical • medium

The number of daily active users (DAU) on WhatsApp has dropped by 3% week-over-week. Walk me through how you would investigate the root cause of this decline.

#Root Cause Analysis #DAU #Metric Debugging

Practice

Data Scientist • Technical • medium

You have two coins. One is fair, and the other is biased, coming up heads 75% of the time. You pick one coin at random and flip it three times. It comes up heads all three times. What is the probability that you picked the biased coin?

#Bayes' Theorem #Conditional Probability

Practice

Data Scientist • Technical • hard

We ran an A/B test on Instagram where we increased the size of the 'Like' button. The results show a 5% increase in likes, but a 2% decrease in comments. Would you launch this change? How do you investigate further?

#Experimentation #Trade-offs #Statistical Significance

Practice

Data Scientist • Technical • medium

Meta is considering launching a new feature that allows users to tip creators on Reels. How would you determine if this feature is successful?

#Product Strategy #Metrics Definition #Reels

Practice

Data Scientist • Technical • medium

What is cross-validation? Explain k-fold and stratified k-fold.

#Cross Validation #k-Fold

Practice

Data Scientist • Technical • easy

What is the difference between Type I and Type II errors?

#Hypothesis Testing #Errors

Practice

Data Scientist • Technical • medium

Explain the bias-variance tradeoff. How does it influence model selection?

#Bias-Variance #Model Selection

Practice

Data Scientist • Technical • medium

How do you approach feature selection?

#Feature Selection #LASSO

Practice

Data Scientist • Technical • hard

Explain Bayesian vs Frequentist statistics. When would you use each?

#Bayesian #Frequentist

Practice

Data Scientist • Technical • hard

How does Meta measure the ROI of a Reels algorithm change?

#Reels #Metrics

Practice

Data Scientist • Technical • hard

What is a 'triggered analysis' in the context of Meta's experimentation framework?

#Triggered Analysis

Practice

Data Scientist • Technical • hard

How would you detect bot/spam activity using data analysis at Meta?

#Bot Detection #Analytics

Practice

Data Scientist • Technical • medium

Explain the difference between bagging and boosting.

#Bagging #Boosting

Practice

Data Scientist • Technical • medium

What is principal component analysis (PCA)? What are its limitations?

#PCA #SVD

Practice

Data Scientist • Technical • medium

Explain how backpropagation works.

#Backpropagation #Neural Networks

Practice

Data Scientist • Technical • hard

What is the vanishing gradient problem? How do LSTM and ResNet address it?

#LSTM #ResNet #Gradients

Practice

Data Scientist • Technical • medium

What is a p-value? Why is a p-value of 0.05 not always sufficient?

#Hypothesis Testing #p-value

Practice

Data Scientist • Technical • medium

Explain the central limit theorem and its importance in data science.

#CLT #Sampling

Practice

Data Scientist • Technical • hard

Explain the transformer architecture. What are attention mechanisms?

#Transformers #Attention #BERT

Practice

Data Scientist • Technical • medium

How would you approach an NLP problem like sentiment analysis from scratch?

#Sentiment Analysis #Text Classification

Practice

Data Scientist • Technical • hard

How do you monitor model performance in production? What is model drift?

#Model Drift #Monitoring

Practice

Data Scientist • Technical • easy

Explain the difference between INNER JOIN, LEFT JOIN, and CROSS JOIN.

#Joins #SQL

Practice

Data Scientist • Technical • easy

What is an experiment holdout group?

#Holdout #Control Group

Practice

Data Scientist • Technical • hard

How would you identify the root cause of a sudden 20% drop in DAU?

#Root Cause Analysis #Debugging

Practice

Data Scientist • Technical • easy

Explain the difference between a leading indicator and a lagging indicator.

#Metrics #KPIs

Practice

Data Scientist • Technical • medium

How do you choose a north star metric for a product?

#Metrics #Product Strategy

Practice

Data Scientist • Technical • hard

What is a network effect in experimentation? How do you handle SUTVA violation?

#SUTVA #Network Effects

Practice

Data Scientist • Technical • hard

How would you design an experiment to measure the impact of a new ranking algorithm?

#Experimentation #Metrics

Practice

Data Scientist • Technical • hard

What is the multiple testing problem? How do you correct for it?

#Bonferroni #FDR

Practice

Data Scientist • Technical • hard

How do you design an A/B test for a new product feature?

#A/B Testing #Statistics

Practice

Data Scientist • Technical • medium

How would you detect and mitigate overfitting in a neural network?

#Overfitting #Dropout #Regularization

Practice

Machine Learning Engineer • Behavioral • medium

Describe a situation where a machine learning model you deployed degraded in production. How did you detect the degradation, and what steps did you take to resolve it?

#Model Monitoring #Incident Response #Ownership

Practice

Machine Learning Engineer • Behavioral • medium

Give an example of a project where you had to pivot your technical strategy halfway through due to changing business requirements or unexpected technical roadblocks.

#Agility #Problem Solving #Resilience

Practice

Machine Learning Engineer • Behavioral • medium

Tell me about a time you had a fundamental disagreement with a cross-functional partner, such as a Product Manager, regarding the choice of an ML metric versus a business metric.

#Conflict Resolution #Cross-functional Collaboration #Business Acumen

Practice

Machine Learning Engineer • Behavioral • medium

Tell me about a time you had to make a difficult trade-off between model accuracy and inference latency. How did you approach the decision?

#Trade-offs #Optimization #System Constraints

Practice

Machine Learning Engineer • Coding • medium

Given two sparse vectors represented as arrays of non-zero elements and their indices, write a function to compute their dot product. Optimize for both time and space complexity.

#Arrays #Hash Table #Two Pointers

Practice

Machine Learning Engineer • Coding • medium

Write a function to sample a batch of data from a large dataset on disk without loading the entire dataset into memory. Implement a custom PyTorch-like DataLoader class with iter and next methods that supports shuffling and batching.

#Object-Oriented Design #Data Structures #Generators

Practice

Machine Learning Engineer • Coding • medium

Given a binary tree, write an algorithm to find the lowest common ancestor (LCA) of two given nodes. Assume each node has a pointer to its parent.

#Trees #Pointers #Hash Table

Practice

Machine Learning Engineer • Coding • medium

Implement a function to calculate the Intersection over Union (IoU) of two bounding boxes. Extend this to implement Non-Maximum Suppression (NMS) for a list of bounding boxes and their confidence scores.

#Computer Vision #Geometry #Sorting

Practice

Machine Learning Engineer • System Design • hard

Design a multimodal content moderation system to detect hate speech in Facebook posts containing both text and images. How do you fuse the modalities?

#Multimodal ML #Classification #NLP #Computer Vision

Practice

Machine Learning Engineer • System Design • hard

Design an Ads Click-Through Rate (CTR) prediction system for Meta's news feed. How do you handle the extreme class imbalance and delayed feedback in ad clicks?

#Ads Ranking #Imbalanced Data #Streaming Pipelines #DLRM

Practice

Machine Learning Engineer • System Design • hard

Design the machine learning architecture for Instagram Reels recommendations. How would you structure the funnel from candidate generation to final ranking?

#Recommendation Systems #Two-Tower Models #Ranking #Candidate Generation

Practice

Machine Learning Engineer • System Design • hard

Design the 'People You May Know' (PYMK) feature. How would you scale the graph traversals and ML inference to billions of users?

#Graph Neural Networks #Link Prediction #Batch Processing #Scalability

Practice

Machine Learning Engineer • Technical • hard

You are training a large PyTorch model across multiple GPUs using DistributedDataParallel (DDP) and notice that the GPU utilization is consistently low (around 30%). How do you diagnose and fix this?

#PyTorch #Distributed Training #Performance Profiling

Practice

Machine Learning Engineer • Technical • medium

In a deep learning recommendation model (DLRM), how do you handle the explosion of vocabulary size for categorical features like user IDs or item IDs?

#Embeddings #Hashing #Memory Optimization

Practice

Machine Learning Engineer • Technical • medium

Explain the difference between Contrastive Loss and Triplet Loss. In what scenarios would you choose one over the other for training a retrieval model?

#Loss Functions #Metric Learning #Retrieval

Practice

ML Engineer • Behavioral • medium

Describe how you collaborated with data scientists to productionize their research code.

#Research to Production

Practice

ML Engineer • Behavioral • medium

Describe a model you deployed to production. What were the biggest challenges?

#Deployment #Challenges

Practice

ML Engineer • Behavioral • medium

What is Meta's approach to responsible AI?

#Responsible AI #Fairness

Practice

ML Engineer • Behavioral • medium

How do you decide when a model is 'good enough' to ship?

#Quality #Judgment

Practice

ML Engineer • Behavioral • medium

Tell me about a disagreement you had with a researcher. How did you resolve it?

#Communication

Practice

ML Engineer • Behavioral • hard

Describe a time you had to re-architecture a system because the original ML approach didn't scale.

#Scalability

Practice

ML Engineer • Behavioral • easy

How do you keep up with the rapidly evolving ML landscape?

#Continuous Learning

Practice

ML Engineer • Behavioral • hard

Tell me about a time an ML model caused an unexpected real-world impact.

#Responsibility #AI Safety

Practice

ML Engineer • Behavioral • hard

Tell me about a time you had to optimize a model for latency without sacrificing too much accuracy.

#Latency #Accuracy

Practice

ML Engineer • Coding • hard

How would you write a batched inference pipeline using Python and Triton server?

#Triton #Batching

Practice

ML Engineer • Coding • hard

Implement a K-means clustering algorithm from scratch in Python.

#K-Means #Clustering

Practice

ML Engineer • Coding • hard

Implement logistic regression with gradient descent in NumPy.

#Logistic Regression #NumPy

Practice

ML Engineer • Coding • hard

Write a custom PyTorch Dataset and DataLoader for irregular time series data.

#PyTorch #DataLoader

Practice

ML Engineer • Coding • medium

Implement a sliding window approach to detect anomalies in a time series.

#Anomaly Detection #Time Series

Practice

ML Engineer • System Design • hard

What is a feature store? Design one from scratch.

#Feature Engineering #MLOps

Practice

ML Engineer • System Design • hard

Design a training and serving architecture for a large language model at scale.

#Infrastructure #Scale

Practice

ML Engineer • System Design • hard

Design a real-time content moderation system.

#NLP #Real-Time

Practice

ML Engineer • System Design • hard

Design a search ranking system for an e-commerce platform.

#Ranking #Relevance

Practice

ML Engineer • System Design • hard

Design YouTube's video recommendation system end to end.

#Recommendations #Ranking

Practice

ML Engineer • System Design • hard

How would you serve a model that needs to respond in under 10ms?

#Low Latency #Serving

Practice

ML Engineer • System Design • hard

Design a system to retrain models automatically when performance degrades.

#Retraining #Automation

Practice

ML Engineer • System Design • hard

How would you build a personalized ad targeting system?

#Targeting #ML Systems

Practice

ML Engineer • System Design • hard

Design a CI/CD pipeline for ML models.

#CI/CD #Deployment

Practice

ML Engineer • Technical • hard

Explain blue-green deployment vs canary deployment for ML models.

#Blue-Green #Canary

Practice

ML Engineer • Technical • hard

How do you detect data drift vs model drift? How do you respond to each?

#Drift #Production

Practice

ML Engineer • Technical • medium

What is shadow mode deployment in ML?

#Shadow Mode #A/B Testing

Practice

ML Engineer • Technical • medium

Explain model serialization formats: ONNX, TorchScript, SavedModel.

#ONNX #Serialization

Practice

ML Engineer • Technical • medium

What is Kubernetes? How is it used for ML model serving?

#Kubernetes #Serving

Practice

ML Engineer • Technical • hard

How do you optimize GPU utilization during training?

#GPU #Performance

Practice

ML Engineer • Technical • hard

Explain mixed precision training (FP16/BF16). What are the risks?

#Mixed Precision #Performance

Practice

ML Engineer • Technical • medium

What are the differences between PyTorch and TensorFlow for production?

#PyTorch #TensorFlow

Practice

ML Engineer • Technical • medium

How do you profile and debug a slow training run?

#Profiling #Debugging

Practice

ML Engineer • Technical • hard

Explain the RLHF (Reinforcement Learning from Human Feedback) training approach.

#RLHF #Fine-Tuning

Practice

ML Engineer • Technical • hard

What is LoRA (Low-Rank Adaptation)? How does it reduce fine-tuning costs?

#LoRA #Fine-Tuning

Practice

ML Engineer • Technical • hard

What is RAG (Retrieval-Augmented Generation)? Describe its architecture.

#RAG #Vector Search

Practice

ML Engineer • Technical • hard

How would you evaluate an LLM for a production use case?

#Evaluation #Benchmarking

Practice

ML Engineer • Technical • medium

Explain vector databases. What are FAISS, Pinecone, and Weaviate?

#Vector DB #Embeddings

Practice

ML Engineer • Technical • medium

What is model ensembling? When does it help, and when does it hurt?

#Ensembling #Performance

Practice

ML Engineer • Technical • hard

How does PyTorch Distributed work for large-scale model training at Meta?

#PyTorch #DDP

Practice

ML Engineer • Technical • hard

Explain how Meta's DLRM (Deep Learning Recommendation Model) works.

#DLRM #Embeddings

Practice

ML Engineer • Technical • easy

What is the difference between a data scientist and an ML engineer?

#Roles #MLOps

Practice

ML Engineer • Technical • medium

Explain the model training pipeline from raw data to deployment.

#Pipeline #Training

Practice

ML Engineer • Technical • medium

What is the difference between online learning and offline learning?

#Online Learning #Batch Learning

Practice

ML Engineer • Technical • medium

How do you handle missing data in ML model features?

#Imputation #Missing Data

Practice

ML Engineer • Technical • medium

Explain gradient descent variants: batch, stochastic, and mini-batch.

#Gradient Descent #Optimization

Practice

ML Engineer • Technical • medium

What are learning rate schedulers and why are they important?

#Learning Rate #Training

Practice

ML Engineer • Technical • hard

Explain the attention mechanism in transformers with mathematical detail.

#Attention #Transformers

Practice

ML Engineer • Technical • hard

What is quantization in neural networks? How does it reduce inference cost?

#Quantization #Inference

Practice

ML Engineer • Technical • hard

Explain knowledge distillation. When would you use it?

#Distillation #Compression

Practice

ML Engineer • Technical • hard

What is the difference between model parallelism and data parallelism in distributed training?

#Parallelism #Training

Practice

ML Engineer • Technical • medium

How do you version ML models and datasets? What tools do you use?

#Versioning #DVC #MLflow

Practice

Product Manager • Behavioral • medium

Tell me about a time a product launch failed to meet its goals. What did you learn, and how did you communicate the failure to Meta leadership?

#Accountability #Post-mortem #Resilience

Practice

Product Manager • Behavioral • medium

Tell me about a time you had to pivot your product roadmap significantly due to a sudden shift in company priorities or resource constraints.

#Adaptability #Prioritization #Stakeholder Management

Practice

Product Manager • Behavioral • medium

Tell me about a time you strongly disagreed with an Engineering Lead on a technical trade-off. How did you resolve it?

#Conflict Resolution #Cross-functional Collaboration #Influence without Authority

Practice

Product Manager • Coding • medium

Write a SQL query to find the top 10% of users by engagement (defined as messages sent) on Facebook Marketplace over the last 30 days.

#Window Functions #Data Analysis #Marketplace

Practice

Product Manager • System Design • hard

Design a system to detect and mitigate spam accounts generated by AI bots on Facebook Threads.

#Trust & Safety #Machine Learning #System Architecture

Practice

Product Manager • System Design • hard

Design the high-level architecture for a real-time collaborative feature in Instagram Notes where multiple users can type simultaneously.

#Scalability #Real-time Systems #Concurrency

Practice

Product Manager • Technical • medium

We want to launch a new paid monetization feature for WhatsApp Business. How do you size the market and set year-one revenue goals?

#Market Sizing #Pricing Strategy #B2B

Practice

Product Manager • Technical • hard

How would you integrate Generative AI (like Llama 3) into Facebook Messenger to increase daily active users among Gen Z?

#Generative AI #User Segmentation #Feature Design

Practice

Product Manager • Technical • hard

Meta's overall ad revenue dropped by 5% yesterday. Walk me through how you would investigate the root cause of this decline.

#Root Cause Analysis #Metrics #Advertising Ecosystem

Practice

Product Manager • Technical • medium

You are the Product Manager for Instagram Reels. What is your North Star metric, and what counter-metrics would you track to ensure you aren't hurting the broader Instagram ecosystem?

#Goal Setting #Ecosystem Impact #Cannibalization

Practice

Product Manager • Technical • hard

WhatsApp Status usage is up 20%, but direct messages sent are down 5%. Is this a good or bad thing? How do you decide whether to intervene?

#A/B Testing #Trade-offs #Data Interpretation

Practice

Product Manager • Technical • hard

Design a feature for Meta Quest to improve remote work collaboration for enterprise clients.

#AR/VR #Enterprise Software #Innovation

Practice

Product Manager • Technical • hard

You are running an A/B test for a new Feed ranking algorithm. Engagement (likes/comments) goes up by 4%, but average session length goes down by 2%. Do you launch this change?

#Experimentation #Ranking Algorithms #Decision Making

Practice

Product Manager • Technical • medium

Meta is considering entering the travel space. How would you design a travel discovery product integrated into Instagram?

#Market Expansion #User Journey #Monetization

Practice

Product Manager • Technical • easy

Describe a product you recently used that you loved, and tell me how you would improve it if you were the PM.

#Product Critique #User Empathy #Design Thinking

Practice

Software Engineer • Behavioral • medium

Describe a project where you had to 'Move Fast' but realized you were accumulating significant technical debt. How did you balance the need for speed with long-term maintainability?

#Trade-offs #Technical Debt #Move Fast

Practice

Software Engineer • Behavioral • medium

Tell me about a time you identified a problem outside of your immediate team's scope and took the initiative to solve it.

#Ownership #Cross-functional Collaboration #Focus on Long-Term Impact

Practice

Software Engineer • Behavioral • medium

Tell me about a time you received critical feedback from a peer or manager that surprised you. How did you process it and what changes did you make?

#Self-Awareness #Growth Mindset #Feedback

Practice

Software Engineer • Behavioral • medium

Tell me about a time you had a technical disagreement with a senior engineer or tech lead. How did you handle the situation, and what was the outcome?

#Conflict Resolution #Communication #Be Direct and Respect Your Colleagues

Practice

Software Engineer • Coding • medium

Given a list of user session intervals [start, end] representing the time a user spent active on the Facebook app, merge all overlapping sessions to return an array of non-overlapping continuous active sessions.

#Sorting #Arrays #Intervals

Practice

Software Engineer • Coding • medium

Given two nodes p and q in a binary tree representing an organizational chart, return their lowest common ancestor (LCA). Each node has a reference to its parent node, but you do not have a reference to the root.

#Trees #Pointers #Linked Lists

Practice

Software Engineer • Coding • medium

Given an array of integers representing daily ad click counts and a target integer k, return the total number of continuous days (subarrays) whose sum of clicks equals exactly k.

#Prefix Sum #Hash Table #Arrays

Practice

Software Engineer • Coding • easy

Given a string s representing a user's text input, return true if the string can be a palindrome after deleting at most one character.

#Two Pointers #String Manipulation

Practice

Software Engineer • Coding • medium

Given a string of '(' , ')' and lowercase English characters representing a malformed mathematical expression in a Meta internal tool. Remove the minimum number of parentheses so that the resulting string is valid and return it.

#Stacks #String Manipulation

Practice

Software Engineer • Coding • medium

Given the root of a binary tree representing a hierarchical DOM structure, return the vertical order traversal of its nodes' values (from top to bottom, column by column).

#Breadth-First Search #Hash Table #Binary Trees

Practice

Software Engineer • System Design • hard

Design a system to track and display 'Trending Topics' (Top K Heavy Hitters) across Facebook and Instagram in real-time. The system must process billions of events per day.

#Stream Processing #Count-Min Sketch #MapReduce #Kafka

Practice

Software Engineer • System Design • hard

Design the Facebook News Feed system. Users should be able to see a continuously updated list of posts from their friends and pages they follow, ranked by relevance.

#Distributed Systems #Database Schema #Caching #Fan-out

Practice

Software Engineer • System Design • medium

Design a distributed Rate Limiter for the Meta Graph API. It needs to handle millions of requests per second globally, ensuring that individual third-party developers do not exceed their allocated quota.

#Rate Limiting #Redis #Distributed Consensus

Practice

Software Engineer • System Design • hard

Design a distributed web crawler that Meta could use to scrape the internet to build an index for a Large Language Model (LLM) training dataset. Focus on politeness, deduplication, and scale.

#Distributed Systems #Graph Traversal #Deduplication #DNS Resolution

Practice

Software Engineer • System Design • hard

Design WhatsApp's end-to-end message delivery system. Focus on how messages are routed when a user is offline, and how media (images/videos) are handled efficiently.

#WebSockets #Message Queues #Blob Storage #E2E Encryption

Practice

Meta

The Interview Loop

Recruiter Screen (30 min)

Technical Loop (3-4 Rounds)

Interview Question Bank

Tell me about an AI project where you had to balance innovation with reliability.

Describe a situation where you had to debug a hard-to-reproduce AI model failure.

Describe an AI product you built from scratch. What were the key technical decisions?

How do you handle stakeholder uncertainty around AI capabilities and limitations?

Tell me about a time you optimized an LLM application for cost or latency.

Describe a time you had to choose between using an AI model and a simpler rule-based system.

How do you stay current with the fast-moving AI/ML research landscape?

Tell me about a time an AI system you built produced unexpected or harmful outputs.

Write a Python class to manage conversation history for a multi-turn chatbot.

Write a retry mechanism with exponential backoff for LLM API calls.

Implement a simple RAG pipeline using Python, LangChain, and FAISS.

Implement a semantic chunking strategy for long documents.

How would you architect an AI platform that supports 1000 concurrent LLM requests?

Design a real-time AI safety filter for user-generated content.

How would you build a multi-modal AI system that processes both text and images?

Design an AI code review system that integrates with GitHub PRs.

Design a document question-answering system using RAG.

Design an AI-powered customer support chatbot for an e-commerce platform.

Design an AI agent system that can autonomously browse the web and complete tasks.

How do you choose the right embedding model for a domain-specific search task?

What is semantic search? How does it differ from keyword-based search?

Explain function calling / tool use in LLMs. How do you implement it?

What is LangChain? What are its key components (Chains, Agents, Tools)?

How do you integrate OpenAI API or Gemini API into a production application?

Explain the difference between dense and sparse retrieval in RAG.

How do you evaluate retrieval quality in a RAG system?

How do you evaluate the quality of an LLM-generated response?

Explain the concept of AI bias. How do you detect and mitigate it in production?

What is AI alignment? What are the key safety concerns with large-scale AI deployment?

What is Constitutional AI? How does Anthropic use it?

How do you red-team an AI system?

What are guardrails in LLM applications? How do they work?

What is streaming response from an LLM API? How do you implement it in a web app?

How do you manage LLM API rate limits and costs in production?

Explain structured output generation from LLMs (JSON mode, Instructor library).

Explain the difference between GPT, BERT, and T5 architectures.

What is prompt engineering? What are few-shot, zero-shot, and chain-of-thought prompting?

Explain how RLHF (Reinforcement Learning from Human Feedback) improves LLMs.

What is RAG (Retrieval-Augmented Generation)? When would you use it over fine-tuning?

Explain the difference between fine-tuning and in-context learning.

What is token context window? How do you handle documents longer than the context limit?

Explain positional encoding in transformers. What are the differences between absolute and rotary position embeddings?

What is hallucination in LLMs? How do you detect and mitigate it?

Explain the difference between autoregressive and masked language modeling.

What is a mixture of experts (MoE) architecture? How does it scale?

Explain how vector similarity search works. What are HNSW and IVF indices?

Compare vector databases: Pinecone, Weaviate, Qdrant, and pgvector.

Tell me about a time you improved the reliability of a cloud-based data system.

Describe a situation where you had to choose between two cloud architectures. How did you decide?

How do you communicate a complex cloud architecture to non-technical stakeholders?

Describe your experience with incident post-mortems. What do you include?

Tell me about a time you had to optimize a system or infrastructure to reduce costs or improve efficiency. What metrics did you use to measure success?

Tell me about a major cloud outage you experienced. How did you respond?

Describe a time you migrated a critical workload to the cloud with zero downtime.

Describe a situation where you strongly disagreed with a senior engineer or a cross-functional partner on an architectural decision. How did you resolve the conflict?

How do you stay updated with new cloud services and features?

Tell me about a time you caused a significant production outage. How did you handle the immediate mitigation, and what was the post-mortem process?

Tell me about a time you significantly reduced cloud infrastructure costs.

Given a massive, 100GB web server log file, write a script to find the top K most frequent IP addresses making requests. The script must run on a machine with only 4GB of RAM.

Write a function to validate if a given string is a valid IPv4 or IPv6 address. Do not use built-in IP validation libraries.

Implement a thread-safe bounded blocking queue. It should support enqueue and dequeue operations, blocking if the queue is full or empty, respectively.

Write a concurrent script in Python or Go to monitor a local directory for new files and upload them to a remote storage service. It must handle network failures and retries gracefully.

How would you set up a streaming data pipeline on GCP using Pub/Sub and Dataflow?

How would you architect a data platform that reduces spend by 40% without impacting performance?

How do you implement disaster recovery for a cloud data warehouse?

Design a photo storage system similar to what Instagram uses. It must handle billions of reads and millions of writes per day with extremely low latency.

Design a distributed caching system for Meta's newsfeed. How do you handle cache invalidation and the 'thundering herd' problem?

Design a globally distributed rate limiter for Meta's Graph API. It needs to handle millions of requests per second and enforce limits based on user ID and application ID.

Design a data lake on AWS using S3, Glue, and Athena.

How do cloud IAM roles and policies work? Explain least-privilege principle.

What is AWS PrivateLink? When would you use it?

How would you implement network segmentation for a multi-tier application?

What are SLOs, SLAs, and SLIs? How do you define them for a data platform?

Explain chaos engineering. How would you implement it for a data pipeline?

How do you do capacity planning for a cloud data platform?