Caches & CDNs

The fastest query is the one you never make.

In this interactive Infrastructure lesson from Stencel Academy you don't just read — you type real commands like redis-cli -h cache-01 GET user:42, redis-cli -h cache-01 SET user:42 '{"plan":"pro"}' EX 300 and watch the machine respond on a live, animated map. It is part of the free How Infrastructure Works course.

Before this lesson

Builds on: Databases: Where State Lives.

What you'll practise

• redis-cli -h cache-01 TTL user:42 — Seconds until this key self-destructs.
• redis-cli -h cache-01 CONFIG GET maxmemory-policy — What Redis evicts when memory fills.
• redis-cli -h cache-01 INFO stats | grep keyspace — Hit rate is the cache's report card.
• dig +short cdn.stencel.ai — A CDN is a cache someone else runs near the user.
• redis-cli -h cache-01 DEL user:42 — Invalidation: when the DB changes, kill the copy.

Terms you'll learn

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