What do you call a server that stores recently accessed web pages for faster access in the
future?
nat device
firewall
caching server
router

Caching server

Explanation:Cache servers are those types of servers that are responsible for the saving the internet function and web pages on the internet  that has been recently accessed or for temporary purpose for time being.It function on the basis of the HTTP feedback by caching them. These server stores the web pages so that in future the user can save time and access those pages easily and faster.