4447f991_P_Guide___HTTP_General_Headers__HTTP_Cache_Control_Directives_HTTP_Message_Type
[Cache-Control Directive] no-cache [Description] When present, forces a caching device to forward any subsequent requests for the same content to the server for revalidation. That is, the cache must check with the server to ensure that the cached data is still valid. Also see the Pragma header description, for an alternative way of accomplishing the same thing. [HTTP Message Type] 
Request or Response
R e q u e s t o r R e s p o n s e
R e s p o n s e
R e q u e s t
The TCP/IP Guide - HTTP General Headers
HTTP Message Type