Software DNS hghi availability and load balancer solution

Does any one know software sollutions (free is preferable) like as cisco GSS and F5 BIG-IP? The main point is that DNS-server (or dns server plugin) must be able to monitor server availability (for example by TCP connect) and from DNS-reply depends on it. I know that it is possible by BIND with set of script. But we are trying to find more usable solution with frendly interface. Thanks a lot.