caching name sever ?

[Brent Clark]

Hi list

I pretty much only want a caching name server

and I have after googling I got this for my named.conf
=============================================
options {
         directory "/var/cache/bind";
         dump-file "/var/cache/bind/named_dump.db";

         query-source address * port 53;

         // If your ISP provided one or more IP addresses for stable
         // nameservers, you probably want to use them as forwarders.
         // Uncomment the following block, and insert the addresses replacing
         // the all-0's placeholder.

          forwarders {
                 168.210.2.2;
                 196.14.239.2;
          };

         #auth-nxdomain no;    # conform to RFC1035
         forward only;

         statistics-file "/tmp/named.stats";

};

         // Disable rndc
         controls { };
=============================================

The question I would like to know is, how long will a domain record remain in a cache, and if its for a short time period, can I extend the time frame that
an the records exist in the cache.

Also, where is the cache. I have got this funny feeling that it all sit in memory of the machine.

If anyone could assist, I would be most grateful.

Kind Regards
Brent Clark