Question about cluster node NodeWeight property

Hi,

I have a three nodes (A/B/C) windows 2008 r2 sp1 cluster testCluster, and installed KB2494036 for three nodes,suppose Node A is a active node.

 I configured node C's NodeWeight property to 0, and node A and node B keep default (NodeWeight=1). I also added a shared disk Q for cluster quorum.

So i want to know if node C and Node B are down , is the windows cluster testCluster down as lost of quorum or keep up?

At the first i thought testCluster should keep up , because the cluster has 2 votes (node A and quorum), node B is down, node C doesn't join voting. But after testing, testCluster  was down as  lost of quorum.

So anybody konw the reason,thanks.