A EDNS aware server is one which returns a EDNS response to at least one of the test queries. A active server is one which returns a response to one of the test queries. Inactive servers are discarded when calculating the EDNS aware percentages.
2014-09-11: Cloudflare replaced server software which only returned a EDNS response when DO was set to one in the request to a server which ignores EDNS in the request.
2014-10-10: Stopped setting AD=1 in test queries.
2014-10-29: Cloudflare restored EDNS support.