cluster questions

Hi all, I had 2 questions regarding clusters:-

1. Is it possible to have an Active-Active configuration with 1 instance
running 2000 & 1 instance running 2005?
2. Is it recommended or required to have cluster servers part of an active
directory domain? Currently we have 2 servers that are part of our domain
and we are contemplating using them for a cluster. They meet all the
hardware & software requirements, but need to check on AD.

TIA!


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