Freshness lifetime
Freshness lifetime is the interval from response generation until its calculated expiration time.
- caching
- freshness
- reuse
Definition
Freshness lifetime is the interval between a response’s generation and its expiration time. A stored response is fresh while its current age is less than that lifetime.
Cache-Control: max-age=600
Expected result: a cache can calculate an explicit freshness lifetime of 600 seconds. Actual reuse also depends on request directives, cache state, validation rules, and other response controls.
Why it matters
Freshness permits reuse without contacting the origin. Once stale, a response normally needs successful validation or a specific stale-reuse allowance before it can satisfy another request.