If your rr table contains more than one address record for the same
name (but with different addresses, of course), MyDNS will serve them up
in a random order each time.
Round robin is used only if all the address records found have an aux
value of 0. If any of the records have an aux value that is
non-zero, load balancing will be used instead. (See Load balancing.)
Note that MyDNS will also return multiple same-preference MX records in random order, to help equalize the load among same-preference MX hosts.