The Response.Expires parameter specifies how long after the time it was requested that a  certain page should remain in the cache.  For instance, if Response. Expires are set to 5, and the page is told to stay in the cache for 5  minutes following the time it was requested.
The Response.ExpiresAbsolute property aids in displaying the precise moment at which a certain  page cache has expired.
Response.ExpiresAbsolute, for instance, provides data such as 14 March 15:40:15. This  information details the time that the page was cached.