High Level Design
How caching works, the five write strategies (read-through, cache-aside, write-through, write-around, write-back), eviction policies, and common pitfalls.
What CDNs are, how they work with edge servers and origin servers, their benefits and challenges, and how to choose the right provider.
Redis architecture, use cases, failure modes and mitigations, design FAQs, and a Memcached comparison — everything needed for a caching deep-dive.