Browser & Web Performance · Middle · Question 41 of 75

What is the `Vary` response header for?

1It marks the response as randomly generated
✓Correct answer: It tells caches which request headers affect the response, so different variants are stored separately
3It lists the HTTP methods the resource supports

Explanation

For example Vary: Accept-Encoding keeps Brotli and gzip variants apart. Varying on very diverse headers like User-Agent hurts cache hit rates.

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