Challenges

Design a content delivery network that caches and serves static and dynamic content from edge locations worldwide. Consider cache invalidation strategies, origin shielding, and geographic routing.

Design a distributed caching layer for a high-traffic web application. Consider multi-tier caching, write-through vs write-back strategies, cache coherence, and eviction policies.

Design a real-time messaging platform supporting 1-on-1 and group conversations. Handle message delivery, read receipts, online presence, message history, and push notifications for offline users.

Design a multi-channel notification delivery system. Route notifications through push, email, SMS, and in-app channels based on user preferences and priority levels. Handle retry logic and delivery tracking.

Design a URL shortening service like bit.ly. Generate short, unique aliases for long URLs, handle redirection, track click analytics, and support custom aliases and expiration dates.

Design a scalable file storage service similar to S3 or Google Cloud Storage. Handle file uploads, downloads, versioning, access control, and metadata management across distributed storage nodes.

Design a distributed key-value store that supports high throughput reads and writes. Consider data partitioning, replication, consistency models, and failure handling across a cluster of nodes.

Design a layer 7 load balancer that distributes HTTP traffic across backend servers. Support multiple balancing algorithms, health checks, session persistence, and graceful server drain.

Design a distributed task queue for processing background jobs. Support delayed execution, retries with backoff, priority queues, dead letter queues, and exactly-once processing guarantees.