GDNS GTM DNS iRule Response Round Robin A Records for SVIP Databases

If you do not have LTM licensed on the unit, you would be best configuring this with 'topology' LB.

Create two pool:

1) with the single IP

2) with the three IPs

Then use Topology to send traffic to pool one if the subnet matches, 0.0.0.0/0 send to pool 2.