Chapter 23 WAN Optimization, Web Cache, Explicit Proxy, and WCCP : Web caching and SSL offloading : Changing web cache settings : Default TTL
  
Default TTL
The default expiry time for objects that do not have an expiry time set by the web server. The default expiry time is 1440 minutes (24 hours) and the range is 1 to 5256000 minutes (5256000 minutes in a year).