Er, LVS, Netscaler, F5, Pen? People have been balancing DNS for ages to avoid the problems inherent to round robin, and UDP is the ideal scenario for DSR. HAproxy is unique in not supporting it, not the norm.
Loadbalancing UDP is trivial but totally useless without protocol awareness. Loadbalancing UDP properly is much less trivial because most UDP-based protocols need to be handled properly and rewritten since they carry IP addresses, ports, and even expect reverse connections (eg: tftp). In fact the only two UDP-based protocols that you can load-balance without doing anything are syslog and DNS. Both of them are useless as they are properly dealt with by the sender.
