Browser & Web Performance · Middle · Question 42 of 75

A response has no `Cache-Control` or `Expires`, but has `Last-Modified`. Can the browser cache it?

1No, it is never cached without Cache-Control
2Yes, forever
✓Correct answer: Yes, it may use heuristic freshness, often around 10% of the time since last modification

Explanation

Heuristic caching surprises people after deploys. Always set explicit caching headers.

Further reading

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