A read-heavy app caches user profiles in Redis. Which caching strategy loads data into the cache ONLY on first read (cache miss → fetch from DB → populate)?
A.Write-through
Write-through updates cache on writes — not on-demand loading.
B.Lazy loading (cache-aside)
Populate-on-miss = lazy loading. Correct.
C.Write-behind
Write-behind defers DB writes — a different pattern.
D.TTL-only eviction
TTL is eviction timing, not a loading strategy.
Why this answer
Lazy loading/cache-aside: app checks cache → miss → fetch DB → store in cache → return. Stale data possible until TTL/eviction. Write-through writes to cache AND DB simultaneously (always fresh, slower writes). The two named strategies are a classic SAA distinction.
Correct answer: B · Last reviewed 2026-11-02
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