Internally we have a bit of a debate how long to set our cache headers for static content to. One person wants it to be 7 days, another 30, another a year. We have an internal policy that once images are published they cannot be changed. They must upload a new image instead. Based on that, how long should we set our duration for based on best practices? Opinions welcome.
Episerver suggests you should cache the "staticFile" and "staticcontent" for at least 365 days.
<clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="365.00:00:00" />
<staticFile expirationTime ="365.00:00:00"
cacheControl="Private" enableOutputCache= "true"/>
and implement the cache bust approach to clear the cache if any change in CSS or js files. One more thing now Episerver also provides you the ability to clear the CDN cache for Paas Portal.