API Design · Middle · Question 25 of 75

Why is the `Vary` header important for caching API responses?

1It sets the cache duration
2It enables compression
✓Correct answer: It tells caches which request headers change the response (e.g. Accept-Language, Authorization), so different variants aren't mixed up

Explanation

Missing Vary can make a CDN serve a German response to an English user, or one user's data to another.

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