Setting an absolute freshness limit

Some objects do not have Expires headers or do not have both Last-Modified and Date headers. You can control how long these objects are considered fresh in the cache by specifying an absolute freshness limit. A longer lifetime means objects are kept in the cache longer. Performance can improve if pages are taken from the cache rather than going out to the network.

Navigate to the Configure > Protocols > HTTP > Cacheability tab.

In the Minimum Heuristic Lifetime area of the Freshness section, specify the minimum amount of time that HTTP objects without an expiration date can remain fresh in the cache before being considered stale. The default value is 3600 seconds (1 hour).

In the Maximum Heuristic Lifetime field, specify the maximum amount of time that HTTP objects without an expiration date can remain fresh in the cache before being considered stale. The default value is 86400 seconds (1 day).

Click Apply.