Four Hundred Fifty Six

A browser sends a request at exactly 09:14:02 and the response below arrives from a CDN edge at 09:14:03 by the browser's own clock.

HTTP/1.1 200 OK
Date: Mon, 17 Aug 2026 09:14:02 GMT
Age: 143
Cache-Control: public, max-age=600, stale-while-revalidate=86400
ETag: "9f1c-3a"
Content-Type: application/json

For how many more seconds may the browser satisfy requests for this URL out of its own cache without touching the network?