DNS load balancing using only iRule or script for QoS performance metrics.

Hi guys, I would like to load balance DNS client on data center with performance metrics like quality of service options: Round Trip Time - Hops - Virtual Server Score - Packet Rate - Topology - Link Capacity - VS Capacity - Kilobytes/Second, but I need least connection metric also on the data center choice. So I would like to know if there is a way to distribuite DNS connection only using scripts or iRule on GTM/DNS and which is the code I have to write to. Thanks so much Fabrizio