how does Bind choose which DNS server to per zone frwrd to?

[Anthony Golia]

Hi.
 
if I have:

options {
        directory "/var/named";
        forwarders {
                172.17.6.6;
                10.5.2.4;
                10.32.3.4;
        };
        forward only;
}; 
.
.
.
zone "foo.bar.com" {
        type forward;
        forward only;
        forwarders {
	 172.17.1.1;
	 10.10.10.1;
	 192.168.12.12;
	};
};

What algorithm will Bind use to determine which DNS server to forward
requests to?  Especially for foo.bar.com?

-- 
Anthony