Twitter / X

Real-time social platform with petabyte-scale data and ML ranking systems.

4 Rounds ~14 Days Hard

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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

All Roles Backend Engineer 35 Cloud Engineer 35 Data Engineer 35 Data Scientist 35 DevOps Engineer 35 Frontend Engineer 35 Full Stack Engineer 35 Machine Learning Engineer 35 Product Manager 35 Software Engineer 35

All Topics Networking 4 Cloud Architecture 3 Culture Fit 3 System Design 3 Algorithms 3 Infrastructure 3 Infrastructure as Code 2 Scripting 2

Cloud Engineer • Behavioral • medium

X has a strong focus on efficiency. Tell me about a time you had to drastically reduce cloud infrastructure costs. What was your approach and the outcome?

#Cost Optimization #Impact #Problem Solving

Practice

Cloud Engineer • Behavioral • medium

Describe a situation where you had to push back on a product or feature deployment because of infrastructure stability or security concerns. How did you handle the conflict?

#Communication #Conflict Resolution #Ownership

Practice

Cloud Engineer • Behavioral • medium

X moves extremely fast and sometimes things break. Tell me about a time you had to deploy a critical fix or make a major infrastructure decision with incomplete information.

#Adaptability #Decision Making #High Pressure

Practice

Cloud Engineer • Behavioral • hard

Tell me about the most complex production outage you've ever debugged. What was the root cause, how did you find it, and what did you do to ensure it never happened again?

#Incident Management #Debugging #Post-mortems

Practice

Cloud Engineer • Behavioral • medium

How do you handle taking ownership of a legacy system where the original creators have left the company, there is minimal documentation, and it frequently fails?

#Legacy Systems #Ownership #Resilience

Practice

Cloud Engineer • Behavioral • easy

Describe a time you automated a tedious operational task. How did you identify the opportunity, what did you build, and how did you measure the impact?

#Automation #Toil Reduction #Initiative

Practice

Cloud Engineer • Behavioral • medium

Tell me about a time you strongly disagreed with a senior engineer or architect on a system design choice. How did you articulate your point, and what was the resolution?

#Communication #Technical Debate #Teamwork

Practice

Cloud Engineer • Coding • medium

Write a Python script to parse a 50GB Nginx access log file and output the top 10 IP addresses making requests. Optimize for memory usage.

#Python #Log Parsing #Memory Management #Data Structures

Practice

Cloud Engineer • Coding • medium

Implement a rate limiter class in Python or Go using the Token Bucket algorithm. It should support multiple users identified by user_id.

#Python #Go #Rate Limiting #Concurrency

Practice

Cloud Engineer • Coding • easy

Write a Bash one-liner or short script to find and gracefully terminate all zombie processes on a Linux machine.

#Bash #Linux #Process Management

Practice

Cloud Engineer • Coding • medium

Given a list of server connection logs represented as [start_time, end_time], write a function to find the maximum number of concurrent connections and the time it occurred.

#Algorithms #Sweep Line #Sorting

Practice

Cloud Engineer • Coding • medium

Write a Terraform module to provision a secure AWS VPC with 2 public subnets, 2 private subnets, a NAT gateway, and strict security groups allowing only internal traffic to the private subnets.

#Terraform #AWS #Networking

Practice

Cloud Engineer • Coding • medium

Implement a function that takes an IPv4 address string and a CIDR block string (e.g., '192.168.1.5', '192.168.1.0/24') and returns a boolean indicating if the IP belongs to the CIDR block.

#Networking #Bit Manipulation #Python #Go

Practice

Cloud Engineer • Coding • medium

Write a script (Python/Boto3 or Bash/AWS CLI) to automate the detection and rotation of AWS IAM access keys older than 90 days across multiple accounts.

#Python #AWS IAM #Security #Automation

Practice

Cloud Engineer • Coding • medium

Given a list of microservices and their dependencies (e.g., Service A depends on Service B), write an algorithm to determine a valid deployment order.

#Graphs #Topological Sort #Algorithms

Practice

Cloud Engineer • System Design • hard

Design the cloud infrastructure to support Twitter's timeline generation at scale, ensuring sub-200ms latency for 500 million daily active users.

#Scalability #Caching #Load Balancing #Microservices

Practice

Cloud Engineer • System Design • hard

X has recently moved several workloads from AWS back to on-prem bare metal to save costs. Walk me through how you would architect the migration of a massive stateful service (like a distributed database) from AWS to an on-prem data center with zero downtime.

#Cloud Migration #Bare Metal #Database Replication #Networking

Practice

Cloud Engineer • System Design • hard

Design a global rate-limiting service for the X API that can handle millions of requests per second across multiple geographic regions.

#Rate Limiting #Distributed Systems #Redis #Concurrency

Practice

Cloud Engineer • System Design • hard

How would you design a highly available, multi-region Kubernetes cluster architecture to host X's core microservices?

#Kubernetes #High Availability #Multi-region #Service Mesh

Practice

Cloud Engineer • System Design • medium

Design a cost-optimized storage tiering system for X's media assets (images and videos) that balances retrieval speed with AWS S3/GCS storage costs.

#Storage #Cost Optimization #AWS S3 #CDN

Practice

Cloud Engineer • System Design • hard

Design an infrastructure deployment pipeline capable of deploying a critical security patch to 10,000+ nodes in under 5 minutes without causing a global outage.

#CI/CD #Automation #Deployment Strategies #Infrastructure as Code

Practice

Cloud Engineer • System Design • medium

Design a distributed caching layer for trending topics that can handle extreme traffic spikes (e.g., during the Super Bowl or a major global news event).

#Caching #Redis #Memcached #Thundering Herd

Practice

Cloud Engineer • System Design • medium

Architect a disaster recovery plan for X's core authentication service. How do you ensure RTO (Recovery Time Objective) is under 1 minute and RPO (Recovery Point Objective) is zero?

#Disaster Recovery #High Availability #Databases #Failover

Practice

Cloud Engineer • Technical • medium

You notice a sudden 500ms latency spike in a critical microservice running on EKS. Walk me through your exact troubleshooting steps.

#Kubernetes #Observability #Networking #Debugging

Practice

Cloud Engineer • Technical • hard

How does Kubernetes handle network partitions between nodes? Explain the split-brain scenario and how etcd consensus prevents it.

#Kubernetes #Distributed Systems #etcd #Consensus Algorithms

Practice

Cloud Engineer • Technical • hard

Describe the process of tuning a Linux kernel for high-throughput network traffic, specifically to handle millions of concurrent TCP connections.

#Linux #Networking #Kernel Tuning #TCP/IP

Practice

Cloud Engineer • Technical • medium

Walk me through the lifecycle of a DNS query when a user types x.com, focusing specifically on how global load balancing and Anycast routing are involved.

#DNS #Load Balancing #Anycast #BGP

Practice

Cloud Engineer • Technical • medium

How do you manage Terraform state for a massive, multi-team infrastructure without causing locking bottlenecks or state file corruption?

#Terraform #State Management #Collaboration #CI/CD

Practice

Cloud Engineer • Technical • easy

Explain the difference between an Application Load Balancer (ALB) and a Network Load Balancer (NLB). When would you explicitly choose an NLB for a service at X?

#Load Balancing #AWS #OSI Model

Practice

Cloud Engineer • Technical • hard

How would you implement zero-downtime database schema migrations for a live service handling 100k queries per second?

#Databases #Migrations #High Availability

Practice

Cloud Engineer • Technical • medium

What happens at the OS and container level when a Kubernetes pod runs out of memory (OOMKilled)? How do you debug and prevent it?

#Kubernetes #Linux #Memory Management #Docker

Practice

Cloud Engineer • Technical • hard

Explain BGP routing. How does X use BGP to announce IP prefixes for its global CDN network?

#BGP #CDN #Routing #Networking

Practice

Cloud Engineer • Technical • medium

How do you secure internal microservice-to-microservice communication across different cloud VPCs or hybrid environments?

#Security #Networking #mTLS #Service Mesh

Practice

Cloud Engineer • Technical • medium

What are the engineering and financial tradeoffs between using managed cloud databases (like AWS RDS or GCP Spanner) versus self-hosting databases on bare metal servers?

#Cost Optimization #Databases #Bare Metal #Cloud Computing

Practice

Cloud Engineer • Technical • hard

Describe how you would architect a Prometheus and Grafana monitoring stack to ingest and query metrics from a fleet of 50,000 servers efficiently.

#Prometheus #Grafana #Monitoring #Scalability

Practice

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The "Standard" Interviewer

Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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Think Out Loud

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