This is a browser design issue not a protocol/server issue. At the time HTTP 1.1 was written browser caches would hold at most a few weeks of browsing history b

This is a browser design issue not a protocol/server issue. At the time HTTP 1.1 was written browser caches would hold at most a few weeks of browsing history before things started falling out so 'permanent' functioned like our intuition Whats more surprising is "13.2.2 Heuristic Expiration"[1] If you specify (or your framework does) a Last-Modified time WITHOUT Cache-Control the browser is free to make up its OWN cache expiration rules (the item is implicitly cacheable) [1] https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html