A.In this FAQ I said it was safe to disable either IPv4 or IPv6.
Clusters like IPv6. If IPv6 is available, your clusters will use it. If IPv6 isn't available, clusters will use IPv6-to-IPv4 tunnels. Only if these tunnels can't be used will your cluster communications us IPv4. Clusters prefer IPv6 but they can use IPv4 if IPv6 is unavailable, and they'll function just fine.
It should be noted that most testing with clustering is done using IPv6, so if you want the most tested solution use IPv6. Also, disabling IPv6 hasn't been shown to solve any problems—typically, disabling other network components like Teredo and TCP Offloading can solve problems, but not disabling IPv6 directly.
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