How do i find out that my dns cache server is caching properly ?

hey im running a cache dns server with BIND on CentOs 6.3 , i was wondering how can i make sure that this server is caching properly and all users are using cached files ?

Just use dig. If you use dig on the server itself and query it, a cached response will have a 0 msec response on it. A recursive one will be longer. You can also use rndc and do a dbdump to look at the current cache. You can get in to logging to see which users are using it but the best thing to do is just make sure all the users computers have their DNS pointed to the server.