DNS customization development on Windows?

I want to implement my own policy for DNS look up on Windows platform (Server 2008), in more details, the customization I mean is when there is a request to look up IP for a host name comes for DNS server, my own cust开发者_如何转开发omization logics (inside DNS) will be called (e.g. find a low working load machine) and return the IP address. My purpose is to implement a load balancer by using DNS customization.

Is there any API/SDK of Server 2008 which could implement my goal or there is a way to implement a DNS from scratch and host on Windows Server (if there is any open source light weighted DNS on Windows which could be easily customized for my purpose, it will be great)?

BTW: either API/SDK/open source on C# or C/C++ are ok for me.

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Don't know if it will exactly solve your problem, but have you investigated using Windows NLB?

http://en.wikipedia.org/wiki/Network_Load_Balancing_Services

It possibly supports custom load balancing logic