You need to check the binding order of the networks if you want to be specific about which interface(s) is the preferred for Cluster communication, since it will use whichever it can.
To view the networks, their metric values, and if they were
automatically or manually configured, run the clustering PowerShell
PS > Get-ClusterNetwork | ft Name, Metric, AutoMetric
By default, all internal cluster network will have a metric value
starting at 1000 and incrementing by 100. The first internal network
which the cluster sees when it first comes online has a metric of
1000, the second has a metric of 1100, etc. We assume that a network
is ‘internal’ if it does not have access to a default gateway. The
initial list of internal networks is determined by the order which the
network adapters were seen by the cluster when it was created.
By default all external cluster network will have a metric value
starting at 10000 and incrementing by 100.
The cluster will then use the order of the metrics as the order of
networks. The lowest network will be used for “Cluster & CSV
Traffic”. The second lowest network will be used for “Live Migration
Traffic”. Additional networks with a metric below 10000 will be used
as backup networks if the “Cluster & CSV Traffic” or “Live Migration
Traffic” networks fail. The lowest network with a value of at least
10000 will be used for “Public Traffic”, and any additional networks
with a metric above 10000 will be used as backup networks for “Public
Traffic”. Give the highest possible values to any networks which you
do not want any cluster or public traffic to go through, such as for
“Storage Traffic”, so that they are never used, or only used when no
other networks at all are available, depending on your settings.
Basically, read this article, it tells you everything you need to know: http://blogs.msdn.com/b/clustering/archive/2011/06/17/10176338.aspx