use var ( ) and add const for rrt banding
Forget RTT banding, just iterate over available nameserver.

Do the simple thing, just iterate. Do try another nameserver
if the first nameserver times out.
Round robin between multiple nameserver

Allow multiple nameserver to be given on the commmand line. Comma
seperated targets. Use the client.Id to round robin between the
different servers (if there).
Increment try on failed DNS forwards.